I personally use a Cinq Plug6 Plus to charge my iPhone, Bluetooth earphones, Bluetooth speaker, eReader, headlamp, GoPro, Garmin Inreach, and a power bank.

This article was originally published in March 2012 but has been updated in Nov 2023.

If you’re bikepacking off-road or spending lots of time on steep mountain roads, you may want to skip on dynamo chargers and instead use a power bank or solar charger. Dynamo chargers are essentially useless at charging power-hungry devices (eg. smartphones) unless you average 12 to 15kph for the majority of your ride (7.5 to 9mph).

That said, hub dynamos can charge power-efficient devices at as little as 5kph/3mph – this includes GPS trackers, GPS navigation devices, or small battery packs. This is one reason why hub dynamos are popular even for off-road ultra events.

If you’re cycling on terrain that has you cycling above and below 12kph, make sure to add a buffer battery into your charging system, which will supply power to your device when the dynamo can not. For example, when climbing at low speeds or when stopped at traffic lights.

The above is a very brief introduction – if you want to learn it all, it could be worth digging into my full series:
Dynamo Hubs
Dynamo Lights
Dynamo USB Chargers
Dynamo Wiring
Buffer Batteries
Rim Dynamos

Key Stats For Benchmarking Hub Dynamo USB Chargers

To help you compare the hub dynamo USB chargers in this resource, I have listed their key specs and have organised them according to type (“integrated”, “inline” and “light” chargers). Within these categories, you’ll also find them ranked in terms of available output power when cycling at 20kph.

Speed at 2.5W – This is the speed you need to ride in order to achieve the minimum charge for many smartphones.
Power at 20KPH – This is the maximum output power at the USB port at 20KPH.
Power Output Graph – The power output graph for the charger if available.
Buffer Battery – If a buffer battery is integrated into the charging system, I have listed the battery’s capacity here.
Price – Retail price on the hub dynamo USB charger.

Integrated Hub Dynamo USB Chargers

Forumslader V6 Ahead

The Forumslader V6 is one of the more powerful dynamo USB chargers above 20KPH. While we don’t have any data on the latest model, the Forumslader V5 was able to hit 2.5 watts at 13KPH and almost 5 watts at 20KPH. A cool thing about the Forumslader products is that they’re constantly getting updated with the latest tech and circuitry due to their small-scale production. If you’d like more protection of the USB port, an aftermarket dust and water protection cap is available HERE.

Speed at 2.5W: 13KPH (V5)
Power at 20KPH: 4.8-watts (V5)
Power Output Graph: HERE (V5)
Buffer Battery: 7500mAh
Price: €227

Cinq Plug6 Plus

The Cinq Plug6 Plus is my dynamo hub USB charger of choice. It’s super neat and offers more power than anything else below 18KPH. There’s an 1100mAh battery hidden in the steerer tube that steps in when your speed drops below 12KPH. Simultaneous operation of lighting and charging is possible, although it will only really maintain your smartphone battery – rather than fill it. The Plug has recently been redesigned to be significantly more waterproof than previous models (mine Plug6 has worked flawlessly for 18 months so far). You can hide the USB-C plug quickly by rotating the ratcheting top cap door, and a waterproof cap can additionally be used in extreme conditions. If you’re after a rare USB-C-to-iPhone cable in a short length, check out this one on Amazon.

Speed at 2.5W: 12KPH
Power at 20KPH: 4.6-watts
Power Output Graph: HERE
Buffer Battery: 1100mAh
Price: €259

Cycle2Charge V3+

This headset top cap option from Cycle2Charge is available at an exceptional price. It produces the minimum charge for a smartphone at 15KPH (2.5W), but it’s between 20 to 25KPH where it provides the bulk of its power. Like the Plug6, this charger uses a rotating dome to protect the USB plug when not in use.

Speed at 2.5W: 15KPH
Power at 20KPH: 4.3-watts
Power Output Graph: HERE
Buffer Battery: No
Price: €80

Sinewave Reactor

The Sinewave Reactor offers notably good reliability and moderate performance. The electronics are neatly integrated into the fork steerer, making it somewhat theft-proof and elegant. It’s manufactured in the USA and gets rave reviews from many users.

Speed at 2.5W: 17.5KPH
Power at 20KPH: 3-watts
Power Output Graph: HERE
Buffer Battery: No
Price: US $220

Cinq Plug5 Pure

The Cinq Plug5 Pure is a lower-cost version of the Plug6 Plus that’s sold without the buffer battery. The charger is not particularly powerful: the maximum output is just 3.1 watts, which is really only suitable for low-draw devices such as a Garmin GPS or Spot Tracker.

Speed at 2.5W: 14KPH
Power at 20KPH: 3.1-watts
Power Output Graph: HERE
Buffer Battery: No, but it is designed to be used seamlessly with the Smart Power Pack
Price: €159

In-line Hub Dynamo USB Chargers

Lumi-Con Bike Harvester PM

The Lumi-Con PM offers amazing specs for the price. It integrates up to 3500mAh worth of batteries that can kick in when you drop to low speeds, or store any excess power for when you’ve finished your ride.

Speed at 2.5W: 15KPH (non-independent testing)
Power at 20KPH: 5.5-watts (non-independent testing)
Power Output Graph: HERE (non-independent testing)
Buffer Battery: 3500mAh
Price: €161

Forumslader Pro V6

The Forumslader V6 is available in a larger unit that will sit inside a handlebar bag for a lower price.

Speed at 2.5W: 13KPH (V5)
Power at 20KPH: 5.1-watts (V5)
Power Output Graph: HERE (V5)
Buffer Battery: 7500mAh
Price: €122

Igaro S1 Pro

The Igaro S1 Pro is a notably high-performing dynamo hub charger, especially at low speeds. It has dual USB-C ports, status indicators, and super-capacitors that add power to your device when you’re cycling at slower speeds. The S1 Pro is IP69 waterproof and mounts directly to your handlebar near the stem.

Speed at 2.5W: 12KPH (non-independent testing)
Power at 20KPH: 5-watts (non-independent testing)
Power Output Graph: Table HERE (non-independent testing)
Buffer Battery: Internal super-capacitors with four minutes of stationary power
Price: £260

Fahrradlader V3.1

The Fahrradlader V3.1 is a small open-hardware project by an electrical engineering student in Germany. The Fahrradlader V3.1 delivers big power at 20kph for very little money, plus it has four supercapacitors that keep the power flowing temporarily when you ride at low speeds. This model is not waterproof and appears to only be made in small numbers (you might need to get your name on a list).

Speed at 2.5W: 16.5KPH (non-independent testing)
Power at 20KPH: 5-watts (non-independent testing)
Power Output Graph: HERE (non-independent testing)
Buffer Battery: Four super-capacitors with stationary power
Price: €35

Igaro D2 Pro R3

The Igaro D2 Pro charger features dual USB-C ports, status indicators, and a metal casing. It’s compact, IP69 waterproof, and hand-assembled in the UK. The charger comes with a five-year warranty, and Igaro will ship warranty replacements anywhere in the world for free.

Speed at 2.5W: 14KPH (R2 model)
Power at 20KPH: 4.1-watts (R2 model)
Power Output Graph: HERE
Buffer Battery: No
Price: £160

Lumi-Con Bike Harvester P5

The Lumi-Con P5 offers excellent specs for the price. It integrates up to 7000mAh worth of batteries that can store any excess power for when you’ve finished your ride.

Speed at 2.5W: 14KPH
Power at 20KPH: 4-watts
Power Output Graph: HERE
Buffer Battery: 2x 3500mAh
Price: €159

Velotor SE2 Base

Speed at 2.5W: 16KPH
Power at 20KPH: 3.6-watts
Power Output Graph: HERE
Buffer Battery: No
Price: €197

kLite USB Charger

kLite makes some amazing light and dynamo systems for remote backcountry use. Their focus is specifically on reliability, so their systems are as simple as possible, using thick internal cabling, full waterproofing, and smoothing capacitors that offer ultra-consistent waveforms (best practice for direct charging; kLite says they take up half the charging unit). The kLite charger also offers solar charger input and 2x USB output ports (1x Spot Tracker or GPS + a smartphone or other power-hungry device).

Speed at 2.5W: 18KPH
Power at 20KPH: 2.8-watts
Power Output Graph: HERE
Buffer Battery: Available separately
Price: US $140

Sinewave Revolution

This small 38-gram waterproof charger can be connected directly to phones or power packs and is especially popular given it offers the same performance as the Reactor but with a lower price tag. It will achieve 2.5W at 17KPH, 3W at 20KPHH, and 4.5W at 30KPH. Like all Sinewave products, it’s made in the USA.

Speed at 2.5W: 17KPH
Power at 20KPH: 3-watts
Power Output Graph: HERE
Buffer Battery: No
Price: US $120

Busch and Muller E-Werk

The E-Werk is a unique unit as you can control the voltage (2.8 to 13.3V) and current (0.1 to 1.5A) to suit the charging specifications for each device you’d like to charge. While it’s a great idea, in theory, it really just makes the charger more complicated than necessary. The only time I can see this feature being useful is if you’re regularly travelling ultra-fast (40KPH+) or slow (<7KPH). In terms of performance, the E-Werk will hit smartphone levels of charging at 17.5KPH, and by 30KPH it will be producing over 4 watts.

Speed at 2.5W: 17.5KPH
Power at 20KPH: 2.8-watts
Power Output Graph: HERE
Buffer Battery: Available separately for $105
Price: €179

Busch and Muller USB-Werk

The USB Werk is the more recent release from Busch and Muller (it’s getting old now). It’s a stripped-back version of the E-Werk but with a tiny buffer battery built-in. It can achieve smartphone levels of charging (2.5 watts) somewhere between 14 and 19KPH (two different tests).

Speed at 2.5W: 14 to 19KPH
Power at 20KPH: 2.6 to 3.3-watts
Power Output Graph: HERE and HERE
Buffer Battery: 300mAh
Price: €110

USB2BYK

Speed at 2.5W: 20KPH (non-independent testing)
Power at 20KPH: 2.5-watts (non-independent testing)
Buffer Battery: No
Price: €39

Kemo M172N

The Kemo M172N is a dynamo USB charger with a built-in switch so that you can choose between sending power to your lights or your USB device. It’s an absolute bargain, and from all accounts, works really well if your average speed is above 25KPH.

Speed at 2.5W: 22KPH
Power at 20KPH: 2.3-watts
Power Output Graph: HERE
Buffer Battery: No
Price: £40

PowerBUG

Another cheap charger from Poland is the PowerBUG. While you need quite high speeds to access smartphone levels of power, it definitely won’t break the bank.

Speed at 2.5W: 25KPH
Power at 20KPH: 2.3-watts
Power Output Graph: HERE
Buffer Battery: No
Price: €38 (169 zł)

Ullmann Power Station 4

Speed at 2.5W: No data
Power at 20KPH: No data
Buffer Battery: No
Price: €130

VeloCharger MK2

Speed at 2.5W: No data
Power at 20KPH: No data
Buffer Battery: No
Price: £105

BioLogic ReeCharge Dynamo Kit

Speed at 2.5W: No data
Power at 20KPH: No data
Buffer Battery: No
Price: US $39

Hub Dynamo Lights with USB Chargers

Spanninga Nomad

The Spanninga Nomad is, by far, the cheapest light and USB charger combo. It has a small form factor, with the USB plug hidden on the side of the lamp. It offers a lower 40 lux light output than the competition (compared to the B&M 90 lux and AXA 70 lux) but offers more USB power at 20KPH.

Speed at 2.5W: 18KPH
Power at 20KH: 3.4-watts
Power Output Graph: HERE
Battery: No
Price: US $50

Sinewave Beacon 2

The Sinewave Beacon 2 is an LED light with 750 lumens output and an integrated switch for charging. The Beacon 2 uses the same internals as the Revolution and Reactor so you can expect a strong smartphone charge at 17KPH. A cool feature is that the light can be powered by the dynamo hub, an external USB battery pack, or both. A blinking mode is also available when external battery power.

Speed at 2.5W: 17KPH
Power at 20KPH: 3-watts
Power Output Graph: HERE
Battery: No
Price: US $350

B&M Lumotec IQ2 Luxos

Introduced to consumers at the 2012 Eurobike tradeshow, this 90lux dynamo light incorporates a handlebar switch and USB plug so that you can charge and ride. It’s a super neat and integrated design, however, comes with mixed reviews when it comes to its charging ability. Even so, this is a great dynamo light with a nice beam shape for on-road use.

Speed at 2.5W: No data
Power at 20KPH: No data
Battery: No
Price: US $260

AXA Luxx70 Plus

The AXA Luxx70 Plus is a similar product to the Lumotec IQ2 light, providing a handlebar switch to select between using the LED light or USB charger. The key advantage of this product is the exceptional price point. From all accounts, it works really well too.

Speed at 2.5W: No data
Power at 20KPH: No data
Battery: No
Price: US $150

Learn About Hub Dynamo USB Chargers HERE, Dynamo Wiring Systems HERE, Buffer Batteries HERE and Dynamo Lights HERE

The post List of Hub Dynamo USB Chargers That Power Your Electronics While You Ride appeared first on CYCLINGABOUT.

I will be explaining how different USB chargers and dynamo hubs will affect the charge rate. We will look at the charge rates both at constant speeds (easy to predict), as well as at varying speeds (hard to predict).

I will also be describing the complexity of predicting charge times on a smartphone (super hard to predict) using some newly available data.

This article is very graph and data-heavy, so hats off if you can digest it all the first time around. Please remember, you can always skip through to the summary at the end if you just want to extract the key points.

Terminology: Volts, Amps, Watts, mAh

To understand this article well, let me briefly explain a few terms.

The voltage (in volts or ‘V’) and current (in amps, or ‘A’) make up the total electrical system power.

I won’t go into too much detail about what these are, but here’s what you should know: the output voltage (V) of a dynamo is fixed (mostly). Almost all dynamo hubs are designed to put out 6-volts in AC power, and once we convert this to the DC power necessary for charging things – we end up with around 5-volts.

It’s the current (A) that fluctuates most in a dynamo charging system. At low speeds, the current will be less than 0.1-amps, and at high speeds, it can be more than 2-amps.

If you didn’t understand that, don’t worry. The most important term to remember is watts, which is the total output power. I will be using watts to benchmark different chargers and hubs throughout this resource.

We get watts simply by multiplying the volts and the amps together. For example, a dynamo hub putting out 5-volts at 1.1-amps will provide 5.5-watts at the USB plug (5V x 1.1A = 5.5W).

And lastly, I’m using milliamp hours, or mAh, when I’m referring to both battery energy capacity and charging rates. You will always find the total energy capacity (in mAh) written on the battery.

Calculating Dynamo Charging Rates

The simplest way to calculate how quickly a dynamo hub can charge devices is to look at a power curve graph. By picking a speed that you often find yourself cycling, you can determine the amount of power available at the USB plug, and the associated charging rate.

Example: 15kph with the Forumslader V5 Ahead Charger
When we follow the light blue Forumslader V5 graph line up to 15kph, we can see it’s producing 3-watts of power. As the voltage is fixed at 5-volts on a dynamo, we can calculate the current to 0.6A, which for an hour of riding is 600mAh. This would mean that when charging my Petzl CORE 1250mAh headlamp battery, it would fill from empty in 2 hours and 5 minutes.

Example: 15kph with the PedalCell Rim Dynamo Charger
The PedalCell (dark blue) is producing over 5-watts (5V and 1.04A) at 15kph, which for an hour of cycling translates to 1040mAh. It would fill my Petzl CORE 1250mAh headlamp battery from empty in 1 hour and 12 minutes.

Note: the data here has been recorded in 5kph intervals. To get a more accurate power output prediction, you should round up or down to the nearest 5kph of what you ride. This is because, in reality, USB chargers offer power in ‘steps’ – you’ll soon visualise this in the section Battery Charging With Varying Speeds.

Battery Storage Losses

The calculations we’ve just made have assumed that all power is going directly to your device. But what if you’re charging into a battery so that you can save the power for later?

When power is stored in a battery, it experiences a storage loss of around 15-20%. This essentially means that you will need to cycle for 15-20% more time to get the same amount of energy to your device.

Using the same examples as previously: if I stored the energy in a battery first, my Petzl battery would require 2 hours and 30 minutes of cycling to fill (Forumslader V5 charger @ 15kph). And I’d need to ride for 1 hour and 26 minutes to fill my Petzl battery, using a PedalCell rim dynamo charger.

Charging Differences Between Dynamo Hubs and USB Chargers

The power curve we previously looked at showed the differences in power available between different USB chargers. But how do dynamo hubs differ in power output?

It turns out, quite a bit…

Example: 15KPH with the Shimano UR700 hub
When we pair the UR700 with the kLite USB charger, the power available is 3-watts (5V and 0.6A), which translates to 600mAh. It would take 2 hours and 5 minutes to charge my Petzl headlamp battery with this combination.

Example: 15KPH with the Schmidt SON28 hub
If we instead use a Schmidt hub with the kLite USB charger, we’d get 1.9-watts (5V and 0.38A), which translates to 380mAh. This means that the charge time on my 1250mAh Petzl battery would be over three hours… or a 36% time difference between hubs.

When we look at the Shimano UR700 data across four different USB chargers, we can see 20-50% more power available at any given speed. While the data is limited to only four chargers, it’s quite likely that this hub will bring a significant boost in power to any dynamo charging setup.

But there is a downside to the UR700 hub – it’s more inefficient than other hubs. The amount of drag it experiences at the wheel is often 2-3x higher than the Schmidt hub, which can really add up to slow you down.

You can read more about dynamo hub drag HERE.

USB Charger Testing With Varying Speeds

While the graphs in the previous sections have given us an idea of the power output at very specific speeds, on undulating terrain, it’s unusual to cycle at a constant speed for long periods of time.

To help simulate undulating riding conditions, Fahrrad Zukunft created a dynamic test with varied cycling speeds to see which dynamo USB chargers could generate the most power.

The test is a little over the top in speed variation, but it’s still pretty interesting to see that some USB chargers are able to adapt to changes in speed better than others.

The test protocol had the cycling speed in 2-second steps from 10kph up to 30kph and then back down to 10kph again. The accelerations between steps took 3-seconds. This 20-minute test essentially exposes the responsiveness of the USB chargers, which are constantly trying to optimise the charging rate.

Output power at the USB port after 20 minutes:
1. Forumslader V5 (1200mWh or 240mAh)
2. Lumi Con P5 (1000mWh or 200mAh)
3. Plug5 Plus (1000mWh or 200mAh)
4. NC-17 Appcon 3000 (900mWh or 180mAh)
5. USB Werk (600mWh or 120mAh)
6. Zjego (400mWh or 80mAh)

Expectedly, the USB chargers with the highest power outputs did the best in this test, although the Lumi Con P5 is a standout because it offers less output power than the other chargers in the top-four, yet still manages to extract a decent charge thanks to how well it handles changes in speed.

Battery Charging With Varying Speeds

PedalCell has recently conducted a lab test (with CyclingAbout contributions ) to see how their rim dynamo deals with changes in cycling speed. You can read a copy of their white paper HERE.

This data is interesting because it shows how the charger constantly optimises the amount of power available at the USB port at different speeds. This is important to understand because it shows that power is delivered to your battery/device in ‘steps’ – not in the way it is depicted in the FahrradZukunft graphs above.

For the PedalCell, at least, the data suggest that around 2mph/3kph is enough to trigger a change in charge rate.

By extracting the power and time information from this graph, we can roughly calculate how much charge the PedalCell can put into a battery pack if you were cycling on undulating terrain (50-second descent followed by a 10-second climb x 60).

If you were riding the same course as the lab test, you could expect 1583mAh per hour. Those are really big numbers for a bicycle dynamo on lumpy terrain!

The Complexity of Calculating Smartphone Charging Rates

One of the most common devices that people charge on bike trips is a smartphone, but here’s the deal: it’s hard to predict charge times on a smartphone because the charging software chooses the charging rate, and there is a lot of variation between software.

The battery percentage is one factor that affects the charge rate of a smartphone – most will allow quick charging when a battery is empty, but will reduce the charge rate as you get closer to 100%.

Another factor is whether the screen is on or off. When the screen is on, a smartphone will usually accept more power than when your phone is on standby.

The apps that you’re using on your smartphone can also affect the charging rate.

And lastly, the dynamo USB charger that you’re using should also support the appropriate USB charging protocols for your smartphone. There are dozens of protocols that have been created by governing bodies and private companies to safely draw the maximum amount of power. If your charger is not using the suitable charging protocol for your smartphone, it may not achieve its full charging rate.

In some cases, smartphones do not charge well from a dynamo because the charging software thinks it is receiving power from a faulty wall charger, resulting in a significant throttling of the charge rate.

One reader has informed me that their Motorola smartphone charges at just 0.3A (1.5-watts) no matter the cycling speed, even though their B&M USB Werk charger should be putting out 0.7A (3.5-watts).

The work-around for this software limitation is to simply charge into a power bank first, before sending the power to your smartphone. Unfortunately, this reader will now have the abovementioned battery storage losses, but they will also get twice as much charge going into their smartphone!

Smartphone Charging With Varying Speeds

Ok, onto the smartphone charging data.

PedalCell conducted a lab test with three different smartphones to see how well their charger would negotiate with the smartphone software to optimise charge speeds. They tested the charging rates of these smartphones with the screen both on and off – I’m using the screen-on data for this resource.

The batteries were all at 40-50% charge – keep in mind that a smartphone tends to charge quickly here, so you will not get the same test results at 80% charge.

To get a sense of an iPhone XR’s charging speed using the PedalCell on hilly terrain, we can extrapolate the data from the graph (30-second descent followed by a 15-second climb x 80).

I’ve calculated that the charging rate is 1666mAh per hour (57% of the battery capacity) on this specific riding course.

The PedalCell has very little negotiation time when charging the One Plus 8 Pro, showing this smartphone to charge in a similar manner to the 10400mAh battery.

So, does that mean it will be getting more charge when compared to the iPhone XR?

When we run the numbers here, the One Plus is getting around 1578mAh per hour into its battery, which is about 35% of its battery capacity. While the negotiation times are quick, the peak charge rate is a little lower than the iPhone, which means that it’s not quite picking up the same amount of charge at higher speeds.

Riding course: 50-second descent followed by a 20-second climb x 51

The Google Pixel (2016) had the lowest charge rate of the smartphones tested.

Interestingly, the Pixel’s software chose to fluctuate the current quite a bit compared to the other phones. PedalCell has suggested it could be because the battery was 4-5 years old, but when we look at the charging rate of the Pixel 2 XL from a wall charger, the phone’s charging rate likely fluctuated out of the box.

Despite a lower peak charging rate of around 8.5-watts, the Google Pixel was still able to charge at 1362mAh per hour, which is 49% of the battery capacity.

Riding course: 38-second descent followed by a 22-second climb x 60

Summary

This topic is a bit of a minefield, so if you’ve read the whole thing – congratulations!

At constant speeds, it’s relatively easy to predict how quickly a dynamo USB charger will fill a regular battery. We can simply look at the FahrradZukunft power output graphs to calculate how much charge per hour is possible. The graphs also indicate that some dynamo USB chargers offer substantially more power than others at different speeds.

Dynamo hubs also seem to offer a surprisingly large difference in charging performance. We can see that the Shimano UR700 has 20-50% more power available than other hubs at any given speed, although, the Skjegg data suggest that this hub has a high amount of drag for the power it offers.

Calculating charge times gets much more complicated when you’re riding in hilly terrain, as some USB chargers are more effective at varying speeds than others. As a general rule, however, the most powerful chargers will extract the most charge from your dynamo.

And finally, charging smartphones.

I wish I could give you a charge time on smartphones, but there are just too many factors to account for.

As we’ve seen with the three smartphones in the PedalCell test, the charging software plays a large role in determining the charging rate. The battery percentage is another factor, where lower percentages usually have the highest charging rates. Whether your screen is on or off, and what app you’re using will affect the charge rate too.

Thanks to PedalCell for collecting the data on charging batteries and smartphones at different speeds so that we can better understand dynamo charging! You can check out how the PedalCell rim dynamo produces more power than a hub dynamo, and at a higher efficiency HERE.

Learn About Dynamo USB Chargers HERE, Dynamo Hubs HERE, Dynamo Wiring Systems HERE, Pass-Through Batteries HERE and Dynamo Lights HERE

The post Lab Test: How Quickly Can You Charge A Battery or Smartphone With A Dynamo? appeared first on CYCLINGABOUT.

You will often hear remarks like ‘my dynamo hub doesn’t slow me down at all’. While it may not feel that way, there is always a cost when it comes to bicycle power production, and today, I’ll tell you how much dynamo drag will likely slow you down.

Finding the exact number is surprisingly tricky. It depends on dozens of factors including (but not limited to) rider weight, fitness level, bike weight, wheel size, tyre width, road surfaces, cycling speed – and the specific hub, charger and lights that are fitted to your bike.

To get a sense of the drag, I will be creating two different rider scenarios and running them on both flat and 5% road gradients. We will then calculate the speed differences of both the highest and lowest-drag hubs when paired with different USB chargers and dynamo lights.

Let’s start with a quick overview of the dynamo components.

The Components That Make A Dynamo Setup

Hub Dynamo
Hub dynamos generate power by passing magnets over a copper coil, and it is here where the physical drag occurs. Hubs actually vary a surprising amount in terms of both power output and efficiency, you’ll be able to see the lowest-drag hubs on some graphs below.

USB Chargers
USB chargers convert the power from your hub into a useable form at the USB plug. Depending on how the electronics have been designed, there are power output and efficiency differences here too. But importantly, the resistance at the wheel is based on how much power your plugged-in device is drawing from the hub, and this can vary quite a bit. For example, a Garmin GPS at 25KPH would likely have 6 or 7x less resistance than a big smartphone.

Dynamo Lights
When it comes to lighting, brighter lights will typically slow you down more than dimmer lights. Most dynamo lights achieve their maximum brightness (and therefore drag) between 15 and 20KPH. Personally, I think lighting is the number one reason someone should use a dynamo setup – they’re just so convenient.

My Two Cyclists

For today’s estimations, we will look at two different rider scenarios.

The smaller rider weighs 60kg and their bike plus gear is 25kg. As the average cyclist pedals at around two watts-per-kilogram on a long ride, this rider will be pushing 120-watts for the simulation.

The bigger rider is 90kg and their bike plus gear is also 25kg. They will pedal their bike at 180-watts.

Dynamo Drag Data And Calculations

I am using dynamo power and drag data collected on Skjegg Blogspot. You can find links to the original test HERE and my interpretation of the results HERE.

I have then used Bike Calculator to determine the speed differences at different power outputs. Through my own real-world testing, I have found this tool to work with very high accuracy.

Hub Dynamo With Nothing Connected

Let’s start with the hub drag with nothing connected. This graph shows the drag of four different dynamo hubs at speeds between 5 and 30KPH. You will notice that most hubs increase in resistance the faster you go; the exception is the Schmidt SON28 which has some black magic going on to achieve a somewhat steady drag at different riding speeds.

Speed difference on the flat:
Smaller cyclist with no dynamo hub – 21.70KPH
Smaller cyclist with the lowest-drag hub – 21.61KPH – 0:14 behind per hour (0.4% slower)
Smaller cyclist with the highest-drag hub – 21.37KPH –  0:54 behind per hour (1.5% slower)
Bigger cyclist with no dynamo hub – 24.62KPH
Bigger cyclist with the lowest-drag hub – 24.56KPH – 0:07 behind per hour (0.2% slower)
Bigger cyclist with the highest-drag hub – 24.32KPH – 0:43 behind per hour (1.2% slower)

Speed difference on a 5% climb:
Smaller cyclist with no dynamo hub – 7.77KPH
Smaller cyclist with the lowest-drag hub – 7.71KPH – 0:29 behind per hour (0.8% slower)
Smaller cyclist with the highest-drag hub – 7.68KPH – 0:43 behind per hour (1.2% slower)
Bigger cyclist with no dynamo hub – 8.64KPH
Bigger cyclist with the lowest-drag hub – 8.59KPH – 0:22 behind per hour (0.6% slower)
Bigger cyclist with the highest-drag hub – 8.56KPH – 0:32 behind per hour (0.9% slower)

Note: for my comparisons, I am subtracting the expected drag of a high-quality hub from all rider scenarios – that’s 0.25-watts at low speeds, 0.5-watts at high speeds.

Hub Dynamo With A Light Connected

For this scenario, we’ll be looking at how much a very bright 100lux dynamo light will slow you down. I have selected the data from the B&M IQ-X, which is one of the brightest options available and one that I personally recommend.

Speed difference on the flat:
Smaller cyclist with no dynamo hub – 21.70KPH
Smaller cyclist with the lowest-drag hub – 20.75KPH – 2:38 behind per hour (4.4% slower)
Smaller cyclist with the highest-drag hub – 20.39KPH – 3:36 behind per hour (6.0% slower)
Bigger cyclist with no dynamo hub – 24.62KPH
Bigger cyclist with the lowest-drag hub – 23.89KPH – 1:48 behind per hour (3.0% slower)
Bigger cyclist with the highest-drag hub – 23.64KPH – 2:24 behind per hour (4.0% slower)

Speed difference on a 5% climb:
Smaller cyclist with no dynamo hub – 7.77KPH
Smaller cyclist with the lowest-drag hub – 7.53KPH – 1:52 behind per hour (3.1% slower)
Smaller cyclist with the highest-drag hub – 7.28KPH – 3:47 behind per hour (6.3% slower)
Bigger cyclist with no dynamo hub – 8.64KPH
Bigger cyclist with the lowest-drag hub – 8.40KPH – 1:41 behind per hour (2.8% slower)
Bigger cyclist with the highest-drag hub – 8.16KPH – 3:22 behind per hour (5.6% slower)

Note: for my comparisons, I am subtracting the expected drag of a high-quality hub from all rider scenarios – that’s 0.25-watts at low speeds, 0.5-watts at high speeds.

Hub Dynamo With A USB Charger Connected

We will be using a kLite USB charger for this example, and we will be assuming that your device is consuming all power available at the USB port. Keep in mind that hub dynamos also vary in power output at the same speed – more power results in more drag. As the Shimano UR700 provides 25% more power at the USB plug than the SON hub, this is not a perfectly fair comparison.

On the 5% climb, I cannot simulate the SON28 as it’s not yet making good power with the kLite charger, so we will compare the two Shimano hubs instead.

Speed difference on the flat (UR700 vs SON28):
Smaller cyclist with no dynamo hub – 21.70KPH
Smaller cyclist with the lowest-drag hub – 21.15KPH – 1:30 behind per hour (2.5% slower)
Smaller cyclist with the highest-drag hub – 20.66KPH – 2:53 behind per hour (4.8% slower)
Bigger cyclist with no dynamo hub – 24.62KPH
Bigger cyclist with the lowest-drag hub – 24.13KPH – 1:12 behind per hour (2.0% slower)
Bigger cyclist with the highest-drag hub – 23.66KPH – 2:20 behind per hour (3.9% slower)

Speed difference on a 5% climb (UR700 vs 3D32):
Smaller cyclist with no dynamo hub – 7.77KPH
Smaller cyclist with the Shimano 3D30 hub – 7.76KPH – 0:04 behind per hour (0.1% slower)
Smaller cyclist with the Shimano UR700 hub – 7.46KPH – 2:24 behind per hour (4.0% slower)
Bigger cyclist with no dynamo hub – 8.64KPH
Bigger cyclist with the Shimano 3D30 hub – 8.61KPH – 0:11 behind per hour (0.3% slower)
Bigger cyclist with the Shimano UR700 hub – 8.38KPH – 1:48 behind per hour (3.0% slower)

Note: for my comparisons, I am subtracting the expected drag of a high-quality hub from all rider scenarios – that’s 0.25-watts at low speeds, 0.5-watts at high speeds.

Bonus: Predicting Time Loss With A More Powerful USB Charger

I personally use a Cinq Plug5 Plus USB charger and Schmidt SON28 hub dynamo on my bike, so I’m running these predictions more for my own curiosity than anything else.

Using the Schmidt hub charging efficiencies from the kLite graph above and the power output figures of the Plug5 Plus from some other independent testing, I can crunch the numbers to try to predict what my more powerful USB charger will likely cost our two simulated riders.

Speed difference on the flat:
Smaller cyclist with no dynamo hub – 21.70KPH
Smaller cyclist with the Schmidt SON28 hub – 20.89KPH – 2:13 behind per hour (3.7% slower)
Bigger cyclist with no dynamo hub – 24.62KPH
Bigger cyclist with the Schmidt SON28 hub – 23.98KPH – 1:34 behind per hour (2.6% slower)

Speed difference on a 5% climb:
Smaller cyclist with no dynamo hub – 7.77KPH
Smaller cyclist with the Schmidt SON28 hub – 7.57KPH – 1:34 behind per hour (2.6% slower)
Bigger cyclist with no dynamo hub – 8.64KPH
Bigger cyclist with the Schmidt SON28 hub – 8.48KPH – 1:08 behind per hour (1.9% slower)

Drag/efficiency figures for these calculations:
kLite efficiency @ 24.6KPH = 59.7% —–> Cinq Plug5 Plus @ 24.62KPH = 5.2-watts —–> Drag is 8.7-watts
kLite efficiency @ 21.7KPH = 57.4% —–> Cinq Plug5 Plus @ 21.70KPH = 4.8-watts —–> Drag is 8.4-watts
kLite efficiency @ 8.64KPH = 28.6% —–> Cinq Plug5 Plus @ 8.64KPH = 0.95-watts —–> Drag is 3.3-watts
kLite efficiency @ 7.77KPH = 28.6% —–> Cinq Plug5 Plus @ 7.77KPH = 0.95-watts —–> Drag is 3.3-watts

How Much Does Dynamo Drag Slow You Down?

The most-efficient hub will slow you down:
10-30 seconds per hour with no lights or chargers attached
1-2 minutes per hour with a USB charger
1.5-2.5 minutes per hour with a bright light

The least-efficient hub will slow you down:
0.5-1 minute per hour with no lights or chargers attached
2.5-3 minutes per hour with a USB charger
2.5-4 minutes per hour with a bright light

Hub dynamos run well with nothing connected. On the flat, my Schmidt hub is probably slowing me down only 7-seconds per hour.

When charging a smartphone, I am likely losing around 1.5 minutes per hour, which I think is very reasonable given how convenient it is to always have power on tap. A low-power device like a Garmin GPS would likely cost me around 20 seconds per hour in comparison.

That said, dynamo lights are my number one reason for using a dynamo setup, and I’m happy to lose a couple of minutes per hour at night for sheer convenience. But if I was ultra racing at the pointy end of the field, this data would make me consider whether I can get by with battery-powered lights, as I could potentially save 25-40 minutes in an overnight push – which is a decent nap!

When an ultra course allows for it, less bright dynamo lights could be a better option. The B&M Cyo, which is half the brightness of the light we simulated (B&M IQ-X), would probably cost around a minute per hour when paired with the Schmidt SON28 hub.

You Can See All Of My Dynamo Resources Listed HERE

The post How Much Do Hub Dynamos Really Slow You Down? appeared first on CYCLINGABOUT.

We can all acknowledge that this was a low point in bicycle power production, but hey, it’s 2020 and technology has progressed. As of this month, if you want to harvest power from your bike, the most powerful and most efficient way is using a modern rim dynamo.

In this resource, we will be examining the pros and cons of rim dynamos and we’ll be looking at the latest performance stats too.

How Do Rim Dynamos Compare to Hub Dynamos?

ADVANTAGES
– You can disengage the rim dynamo completely (dynamo hubs have 1-5 watts friction while spinning with nothing connected)
– You don’t need to rebuild a wheel if there is a dynamo failure.
– It’s an easy install and you can take it off your bike when you don’t need it (or transfer it to another bike).
– The best rim dynamo can harvest 40-70%(!) more power than a hub dynamo.
– The best rim dynamo is 10-20% more efficient than the best dynamo charging setup.
– The lightest rim dynamo is 200+ grams less weight than a hub dynamo setup.

DISADVANTAGES
– Rim slippage above 25KPH (this is only relevant if your plugged-in device is drawing lots of power).
– Rim dynamos make more noise than a dynamo hub (listen HERE).
– Regular replacement of the o-rings is required (3000-7000km is the estimated wear life).
– They probably won’t work well with rim contaminants (eg. thick mud).
– The most powerful, most efficient option is not particularly elegant.
– Only a handful of dynamo lights and two USB chargers are compatible.
– There could be a lot of drag at high speeds… if your plugged-in device is consuming high amounts of power (I’ll clarify below).

Rim Dynamo Products In This Comparison

PedalCell Rim Dynamo and Charger Kit // US $299 and 450 grams
This three-phase rim dynamo is a charging-only kit with everything you need to start a bicycle power station! The “Smart Power Hub” simply attaches to your stem, and it has two USB-C charging ports – a “safety” port with 3-watts maximum power and a “high-power” port with more than 10-watts of available power. Inside is a series of supercapacitors that deliver a stable power output and can keep the power running to your device for about 30 seconds if you stop.

You can see the PedalCell rim dynamo kit on the PedalCell website.

Velogical Special 3-Phase Rim Dynamo and Charger // €365 and 180 grams
This new three-phase rim dynamo from Velogical is designed specifically for low-speed riding and charging. It’s a much more versatile dynamo than the PedalCell, as it can be run with dynamo lights. There are two different charging options too – an in-house charger and an aftermarket charger (Forumslader), both incorporating buffer batteries for constant power flow to your device (if you stop at some traffic lights, for example). On top of its versatility, it looks good, and it’s incredibly small and lightweight – you can expect a charging kit to be under half the weight of the PedalCell.

You can see the Velogical rim dynamo and charger on the Velogical website.

The Test

Olaf Schultz and Andreas Oehler over at FahrradZukunft have done all the heavy lifting to make this data possible. Their rear frame triangle test stand is able to measure torque and speed, and take all the necessary electrical measurements (volts, current, power etc).

If you’d like to know more, the test rig is described in detail in the article, “Current rim rotor dynamos in the laboratory test”.

How Much Power Can A Rim Dynamo Generate?

The PedalCell offers significantly more power than any other USB charging system, it’s 42-70% more power than the best hub dynamo charging setup tested (Schmidt SON28 dynamo hub & Forumslader V5 charger).

The PedalCell is especially impressive at low speeds where it’s already delivering 2.5-watts* before 9KPH.

The Velogical rim dynamo with the Forumslader USB charger is a bit slow to get started, but once it hits 15KPH, it has found its stride and is generating more power than the best hub dynamo charging system – although the additional power is a more modest 10% gain.

You can see the full FahrradZukunft results HERE.

The Best Hub Dynamo Charging System:
1.7-watts @ 10KPH
3.4-watts @ 15KPH
4.8-watts @ 20KPH
7.0-watts @ 25KPH

PedalCell Rim Dynamo:
2.9-watts @ 10KPH – 70% more power
5.2-watts @ 15KPH – 53% more power
7.3-watts @ 20KPH – 52% more power
10-watts @ 25KPH – 42% more power

Note: the PedalCell and Velogical rim dynamos were pre-production units sent in for this test. I’ve been in contact with both manufacturers and they are each claiming improvements over this already impressive data. Velogical says that their “Universal SQ” charger will hit approximately 4-watts at 15KPH and 7-watts at 20KPH. You can see the Velogical power curve HERE.

The Power Is Great, But Are Rim Dynamos Efficient Too?

Dynamo efficiency refers to the amount of power available relative to the amount of drag slowing you down. There is simply no free ride when it comes to harvesting pedal power – you always have to work a bit for it – but a higher efficiency means that more of your pedal power can go directly to charging.

The PedalCell has been tested to be more efficient (68%) than the best dynamo hub and the Velogical works out to be only a touch more efficient (35%) than a lower-performing hub. The highest-performing dynamo hub can average 50-60%* efficiency when charging while the lowest-performing hubs averages between 30-35%*.

You can read my full hub dynamo efficiency analysis HERE.

*These dynamo efficiency numbers are from a different test rig under a different testing protocol. In addition, less power was getting drawn on the hub dynamos, so please just use these numbers as a guide.

I’ve calculated the following numbers based on the dynamo drag at the wheel vs. how much output power is offered at the USB port:

PedalCell Rim Dynamo USB Charger
71% @ 10KPH
71% @ 15KPH
66% @ 20KPH
68% @ 25KPH
68% average efficiency between 15-25KPH

Velogical Rim Dynamo with Forumslader USB Charger
7% @ 10KPH
29% @ 15KPH
37% @ 20KPH
41% @ 25KPH
36% average efficiency between 15-25KPH

Velogical Rim Dynamo with Velogical USB Charger
21% @ 10KPH
31% @ 15KPH
35% @ 20KPH
39% @ 25KPH
35% average efficiency between 15-25KPH

How Quickly Can The PedalCell Fill A 5000mAh Battery Pack?

If you were touring at 15KPH, the PedalCell would be putting out 5V and 1.04A, which for an hour of riding is 1040mAh. A 5000mAh battery pack would then take 4 hours and 48 minutes to charge from empty.

However, there are also small losses in the charging circuitry, typically 10-30% of the total generated power. If we add 20% to the ride time (5 hours + (5 hours x 0.2)), we’re looking at 5 hours and 45 minutes of riding to fill the battery from scratch.

At 20KPH, the PedalCell will be putting out 5V and 1.46A, which for an hour of riding is 1460mAh. The same 5000mAh battery pack would take 4 hours and 6 minutes to charge, including the battery storage losses, at this higher speed.

High Power Output = High Drag

While the efficiency is excellent, especially on the PedalCell, there is a high drag associated with these rim dynamos simply because of the high amounts of power they can generate.

But importantly, a rim dynamo will only have a high drag if your plugged-in device is drawing a high amount of power too.

I’d recommend charging smaller devices if travelling at high speeds, ideally things that require less than 5-watts of power. The PedalCell actually has a “safety” USB-C port which will only allow a maximum of 3-watts – that would be perfect for high-speed use.

Velogical Special vs. PedalCell

The PedalCell has only just been launched (2020), so I have no idea whether it’s durable, waterproof or reliable (2022 update: some users have now reported their units failing, and this video shows the magnets not being glued in properly – make sure to do a bit of research before buying).

I have recently spoken to the team behind the product who have informed me that the production unit is more powerful again, fully water sealed, and is more compact than the prototype unit tested by FahrradZukunft. The production version is now expected to exceed 70% efficiency, which is incredible.

There is a very strong case for the PedalCell if, like me, you travel at speeds averaging between 8 and 20KPH. The drag is low and the power output is high at these speeds – there is simply no hub dynamo setup that gets close at low speeds.

Keep in mind, there is no buffer battery in the PedalCell system, so you’ll want to add one if you’re riding up hills (below 8KPH) or wanting to charge things on routes with lots of stop-start (eg. traffic lights that are longer than 30 seconds).

Unlike the PedalCell, the Velogical Special is super compact, elegant, lightweight and can be used in conjunction with dynamo lights. Both the Velogical and Forumslader USB chargers include buffer batteries for start-stop and the Forumslader USB charger can be integrated very neatly into your steerer tube too. As the Velogical dynamos have been sold for many years, there should be no issues with reliability.

While the PedalCell offers 2.5-watts at 9KPH, you’ll need to maintain 14KPH to achieve the same power with the Velogical kit, so make sure you’re averaging >15KPH to make the most of charging with the Velogical.

Rim Dynamo Summary

Initially, I was very surprised by these results.

But the more I thought about it, the more it makes sense that a rim dynamo can provide so much power at such high efficiency. Everything in the PedalCell charging system, in particular, has been optimised to work together – from the rim dynamo through to the charging circuitry.

In comparison, hub dynamos and chargers are always compromised as they need to be compatible with hundreds of lights and dozens of USB chargers. In addition, hub dynamo equipment is always designed around German legal regulations (StVZO) in terms of power output, which likely throttles what is technologically possible.

In the last decade, we have gone leaps and bounds in terms of dynamo charging setups, so I’m really looking forward to seeing how both of these rim dynamos develop in the coming years. If the current test results are anything to go by, the future is looking very bright for this charging technology.

Learn About Dynamo USB Chargers HERE, Dynamo Hubs HERE, Dynamo Wiring Systems HERE, Pass-Through Batteries HERE and Dynamo Lights HERE

The post Rim Dynamos Can Now Generate 70% MORE Power Than Hub Dynamos appeared first on CYCLINGABOUT.

This comprehensive new testing paired four dynamo hubs with different lights and USB chargers, taking measurements at speeds between 0 and 30KPH. Based on the findings, I’m very surprised to discover how different a simple 6-volt, 3-watt dynamo hub can perform.

This is going to be a technical article but stick with it if you can. The results reveal some very important information about how to best pair dynamo hubs with different dynamo lights and USB chargers.

The Dynamo Hubs On Test

The Schmidt SON28 (pic 1) hubs have always been the industry standard in terms of both efficiency and reliability. These German-made hubs are also the most expensive (US $280+); so does the performance of the hub match the price?

Shimano, who are the largest dynamo hub manufacturer in the world, recently released the Shimano DH-UR700 (2nd pic) and they’re claiming it has 44% less drag than the previous generations (no speed or resistance specified). Thanks to a new alloy axle, it weighs just 477 grams which makes it the lightest hub dynamo Shimano has ever made.

The Shimano DH-3D32 (pic 3) is an older and more cost-effective dynamo hub – in fact, you can have almost three of these hubs for the price of a SON28! The downside is that it’s 685 grams, which is almost twice as much as as the lightest hub in the test. Let’s see if it can make up for its hefty weight with a stellar performance.

The Shutter Precision PD-8 (pic 4) has grown in popularity in recent years thanks to its modest cost (US $130) and ultra light weight (it’s just 410 grams).

You can learn everything I know about dynamo hubs HERE.

The Dynamo Lights On Test

The kLite Bikepacker Ultra (pic 1) is the brightest dynamo light on the market, putting out a whopping 1300 lumens at 25km/h. There are two beam patterns available, a narrow and long beam for the road, and a short and wide beam for off-road. This handmade unit isn’t cheap (US $220), but it’s a very well-proven product in the ultra-racing world.

The Busch & Muller IQ-X is one of the brightest lights available for the road (100lux), with a near-perfect beam shape for everything but singletrack (in my opinion). It also meets the StVZO regulations in Europe so you can legally use them around the streets (basically, the light doesn’t shine oncoming people in the eyes). At US $163, it’s pricy – but hey, it has the brightest legal beam available.

The Supernova E3 PURE 3 is a beautiful German-made light. At 205 lumens it’s not the brightest, but it’s waterproof (it will literally run submerged underwater), ultra-light (90g!), has a StVZO beam and has a five-year warranty. This model doesn’t come with an on/off switch, but the E3 PRO 2 does (this is what I recommend on Amazon US $183).

The Spanninga Nomad is an ultra-cheap city light with about 40lux of light (that’s 40% the light of the IQ-X). The beam is not particularly long or bright, so it’ll be best for slower riding speeds in illuminated areas.

You can read everything about the best dynamo lights for bicycle travel HERE.

The Dynamo USB Chargers On Test

The kLite USB (pic 1) has been developed specifically for the backcountry. While not the most powerful charger available, the emphasis of this unit is on reliability. As a result, the kLite is as simple as possible, using thick internal cabling, full waterproofing and smoothing capacitors that offer ultra-consistent waveforms to your device.

The Igaro D1 (pic 2) is a discontinued dynamo USB charger from Igaro in the UK. It features a very compact size, titanium body and IP69 waterproofing – all in an ultralight package.

One of the original USB chargers is the B&M USB Werk (pic 3). It has a built-in cache battery which, for a short time, can add power to your device when going up hills or stopping at traffic lights.

The Spanninga Nomad (pic 4) is the same dynamo light as above, but the cool thing is it also has a USB charger built-in! Let’s find out if an ultra-cheap, integrated unit like this can also offer a decent charge.

You can read my detailed resource covering the best dynamo USB chargers HERE.

The Lab Test

The Skjegg test rig is essentially a fork and dynamo front wheel, which has been clamped onto a heavy steel plate. Replacing the disc rotor is a cog which connects via a chain to an electric motor mounted on the steel plate. The electric motor is then connected to a laboratory DC power source, where you can control the voltage, and therefore, wheel speed. Speed ​​is monitored by a bike computer and the voltage is measured with a multimeter. Multiplying the readings of the devices, you can calculate the power that the engine needs to consume to spin the dynamo to the required speed. The power of headlights and USB chargers was measured to an accuracy of 0.1 W and the speed to an accuracy of 0.1KPH.

The hub drag is measured indirectly at the electric motor, rather than at the dynamo hub. To determine the dynamo hub drag, Skjegg had to first find all of the drag losses in his test rig. He used a standard bike hub to determine a baseline system drag which could then be subtracted from the drag results of the dynamo hubs (at varying speeds, with different lights and chargers connected). With the influence of slight variations in chain tension between hub tests, the drag has been measured to an accuracy of 1-watt.

It’s worth noting that this test was conducted with quick-release hubs only. Thru-axle and fat bike dynamo hubs might yield different results due to the varying magnet systems.

If you would like to read more about how Skjegg conducted their test, please go to part three of their original article HERE.

Results: Drag Difference Between Lights & Resistors

The FahrradZukunft dynamo test that I previously analysed connected an electrical load resistor (rather than a dynamo light/charger) to different dynamo hubs to find the drag. This is an ok way to benchmark different hubs against each other, but according to Skjegg, it doesn’t accurately measure the drag.

Skjegg show in the graph above how a dynamo light and resistor can consume virtually the same amount of power but have a significantly different drag. Importantly, the drag numbers you see below have been extracted from actual dynamo lights and USB chargers – not resistors.

Results: Maximum Power Point Tracking (MPPT)

Another interesting thing that Skjegg revealed was the maximum power available at different speeds from a Shimano UR700 dynamo hub. Actually, dynamo hubs will put out more power than this but this is the maximum power with the minimum drag.

Using a rheostat, the resistance was manually adjusted until the maximum power output was found at different speeds. As you can see in the graph there is a relatively large difference between the Igaro D1 USB charger output power and the MPPT of the Shimano UR700 hub (it’s often 50% more power).

MPPT of a UR700 Hub vs. Best Dynamo USB Charger Currently Available
5KPH – 1.5W (MPPT) and 0.25W (Forumslader V5)
10KPH – 2.6W (MPPT) and 1.7W (Cinq Plug5 Plus)
15KPH – 4.2W (MPPT) and 3.5W (Cinq Plug5 Plus)
20KPH – 6.0W (MPPT) and 4.8W (Forumslader V5)
25KPH – 7.7W (MPPT) and 6.5W (Forumslader V5)
30KPH – 9.1W (MPPT) and 7.4W (Forumslader V5)

Currently, the biggest areas of improvement in charging look to be found between 5-10KPH where we are only extracting 17-65% of the maximum power available from the hub. After 15KPH, we are already able to charge at 80%+ of the maximum power.

Results: Maximum Power Point Tracking (MPPT) vs. Drag

Skjegg also found the MPPT of the other three dynamo hubs. As you can see, the Shimano hubs (new and old) offer the most output power, followed by the Schmidt SON28 and SP PD-8.

He then graphed the MPPT alongside the hub drag. Shimano’s new UR700 hub can technically offer less drag than the older 3D32 despite developing more potential power – a nice update. The Schmidt SON28 offers the smallest difference between output power and drag, indicating it is the most efficient. And the SP PD-8 is the least powerful hub with a somewhat high drag, especially at speeds above 20KPH.

Results: Dynamo Hub Drag (Electronics Off)

Light/USB Switched OFF While Cycling @ 10-30km/h
Schmidt SON28 // 1.40w-1.90w drag
SP Dynamo // 1.90w-5.20w drag
Shimano UR700 // 1.40w-4.50w drag
Shimano 3D32 // 1.90w-4.30w drag

This test determines how much extra resistance your dynamo hub creates when there is nothing connected.

The drag between 5-10km/h is within 0.5-watts for all dynamo hubs, but when we hit 15km/h the differences become much more pronounced, with the highest-performing hub (SON28) running 1.1-watts less resistance than the lowest-performing (SP). The difference in drag continues to increase as the speeds get higher; the biggest difference is at 30km/h where the SON has 3.3-watts less resistance than the SP, and 2.5-watts less resistance than the Shimano hubs.

Results: Dynamo Hub Drag and Output Power Using Different Lights

Key Talking Points for the kLite Bikepacker Ultra:
– The Shimano UR700 hub provides the most light from 5KPH to 17.5KPH, with a maximum brightness at 20KPH (6-watts).
– The SON28/3D32 hubs offer the most light from 17.5KPH to 22KPH, with a maximum brightness at 20KPH (7-watts).
– The SP PD-8 hub offers the most light after 22KPH.
– Compared to the SON28, the SP offers 35% more power to the light at 25KPH.
– The drag is lowest for the SON28 at maximum power (18-watts), but not by much.
– At low speeds, the drag is considerably higher with the UR700 hub (but you get 10-25% more light).
– The drag is 24.5-watts(!) with the SP at maximum power; if you want a bright-as-hell light, you’ve gotta pedal hard for it.
– Average lighting efficiency between 10-30KPH: SON28 (42.6%), 3D32 (38.2%), PD-8 (32.7%), UR700 (31.3%).

Key Talking Points for the B&M IQ-X:
– The UR700 again provides the most light up until 12.5KPH, but it has considerably more drag too (14.5W @ 15KPH!).
– The 3D32 hub offers exceptional power at 15KPH and relatively low drag at higher speeds too.
– The SP provides the least light until 18KPH, but the most light above 20KPH.
– The SON28 offers 3 to 4-watts less drag than the SP or UR700 hubs at speeds above 20KPH.
– The drag numbers for the SP are quite high compared to the SON28 considering it’s only providing 10% more light.
– Average lighting efficiency between 10-30KPH: SON28 (42.1%), 3D32 (39.2%), PD-8 (34.0%), UR700 (30.8%).

Key Talking Points for the Supernova E3 Pure 3:
– This light is clearly optimised for speeds above 25KPH as it has pretty low power outputs at slow speeds.
– The good news is that the drag is low at slow speeds as a result of the low power outputs.
– The UR700 extracts the most out of the light at all speeds.
– At 25 to 30KPH, the SON28 or 3D32 are the best options when considering both the brightness and drag.
– Average lighting efficiency between 10-30KPH: SON28 (43.6%), 3D32 (39.7%), UR700 (33.0%), PD-8 (32.2%).

Key Talking Points for the Spanninga Nomad:
– The output power is very low, only 40% of the B&M IQ-X.
– The output power is obviously optimised for city riding, with maximum power available at 10KPH on my hubs.
– For the same brightness, the SON28 has 30-50% less drag than other dynamo hubs.
– Average lighting efficiency between 10-30KPH: SON28 (45.9%), 3D32 (31.5%), PD-8 (26.7%), UR700 (24.4%).

Results: Dynamo Hub Drag and Output Power Using Different USB Chargers

Key Talking Points of the kLite USB Charger:
– The Shimano UR700 is a great option at lower speeds, offering 1-2 watts more power than the SON28.
– The SP PD-8 requires a high average speed (18KPH) to meet the minimum charging specification for a smartphone (2.5W).
– The Shimano hubs are the only option with the kLite that can charge batteries at under 10KPH (kLite claim down to 8KPH).
– The SON28 drag is significantly lower than the SP, yet offers more power.
– Average charging efficiency between 15-30KPH: SON28 (60.2%), 3D32 (44.5%), UR700 (39.8%), PD-8 (31.9%).

Key Talking Points of the Igaro D1:
– The power and drag curves are little unusual on all but the SP PD-8 hub.
– The D1 offers exceptional charging efficiency with the SON28 at 20KPH in particular (84%!).
– The charger requires a minimum of 13KPH (UR700) to 17KPH (SP) before it will hit smartphone charging specification (2.5W).
– The Shimano UR700 can provide 2-3W extra power at 30KPH (with a lot of extra drag).
– Average charging efficiency between 15-30KPH: SON28 (59.9%), 3D32 (43.9%), UR700 (40.5%), PD-8 (33.5%).

Key Talking Points of the B&M USB Werk:
– The USB Werk requires 13KPH (3D32) to 17.5KPH (SP) to hit the smartphone charging specification (2.5W).
– Maximum power output at 30KPH varies very little, but the drag is 40% lower on a SON28 hub.
– The USB Werk looks to have been optimised for the SON28 as it offers moderate power with the lowest drag.
– Average charging efficiency between 15-30KPH: SON28 (48.5%), 3D32 (39.3%), PD-8 (31.7%).

Key Talking Points of the Spanninga Nomad Charger:
– The charger will not be very useful until 17 to 21KPH when it can hit the smartphone charging specification (2.5W).
– At speeds between 20 and 30KPH it is actually a very solid little charger, offering more power than most.
– When using the UR700 hub the drag is very high in proportion to the power output (the 3D32 would be the better buy).
– Average charging efficiency between 15-30KPH: SON28 (56.9%), 3D32 (43.6%), UR700 (38.6%), PD-8 (34.4%).

Which Dynamo Hub Is The Best?

The Schmidt SON28 is incredibly efficient across the board making it the undisputable king of dynamo hubs. Despite it usually running the least amount of drag, it offers the 2nd or 3rd-most power in all cases (with ~57% efficiency on charging). Not only that, but SON28 hubs are reliable and use high-grade SKF sealed bearings to help them run smoothly for more than 50,000km. These hubs are super expensive but, in my opinion, are quite good value when you consider the performance on offer.

The Shimano DH-UR700 consistently offers the most power at speeds between 5KPH and 15KPH (3-9MPH), so it’s going to be a great option for off-road or hilly terrain. It’s also often the most powerful hub for charging devices. The only downside is the drag – the hub is powerful but slow. In fact, you’ll often find the drag is 50% less on the SON28.
Shimano UR700 Quick Release – US $152 (Amazon Special HERE)
Shimano UR705 12mm Thru Axle – US $123 (Amazon Special HERE)

The Shimano 3D32 is a $99 dynamo hub that packs amazing performance for the price. When we factor in both the output power and drag, this cheap hub ranks 2nd after the SON28 in almost all cases (~44% charging efficiency). If you are choosing between the Shimano hubs, this would be the one to pick if (a) your average speeds are higher than 18KPH and (b) you don’t mind the extra 200+ grams.
Shimano S501 Quick Release (same internal unit & performance) – US $99 (Amazon Special HERE)

The SP PD-8 offers the most power at high speeds with both the kLite Bikepacker Ultra and B&M IQ-X lights. But otherwise, the results are quite disappointing, especially when paired with a USB charger where it offers the least amount of power of all hubs and poor average efficiency of ~34%. That said, the output power and drag information are just one aspect of a dynamo hub – SP hubs are still great! They work out to be very reliable, ultra-lightweight and affordable, especially the 15mm axle version which is literally half the price of a SON28 ($185 vs $350).
Exposure Revo 15mm Thru Axle (same hub as SP) – US $185 (Amazon Special HERE)

Note: You can support this website by purchasing dynamo hubs through Amazon. I make a small commission on any sales, at no cost to you!

Summary

This data sheds a lot of light (pardon the pun) on the differences between dynamo hubs. I’m quite surprised by these results as I had no idea there was so much performance variation between hubs, in both drag and power output.

Until now, the differences between dynamo hubs have been a bit of a mystery. This is because almost all lab tests have used Schmidt SON28 hubs for power generation. In addition, previous dynamo light tests have used electrical load resistors to simulate the output power rather than actual lights. As Skjegg Blogspot have shown, there is a marked difference in hub drag when we connect a dynamo light.

The amount of drag in Shimano and SP dynamo hubs is higher than I understood it to be. Previously I have stated that dynamo hubs have a charging efficiency of between 50-60%, but this new data shows that only the Schmidt SON28 can claim that with a 57% charging efficiency. Comparatively, the Shimano hubs run between 39-44% efficiency while the SP hub works out to be 34% efficient.

Assuming you’re generating 4-watts of USB power from your dynamo hub when you use an SP PD-8 over a Schmidt SON28, you can expect more than 5-watts of extra hub drag – that’s a lot! I’ll have to write a more detailed article on how drag affects your speed soon.

The post NEW Dynamo Hub Power and Drag Testing: Schmidt SON vs Shutter Precision vs Shimano appeared first on CYCLINGABOUT.

These special batteries provide continuous power to your devices during times when your speed is too low for USB charging, for example, when cycling on hilly terrain, or when stopped at traffic lights. This prevents your devices from receiving then losing charge (eg. smartphones) or switching themselves off entirely (Garmin eTrex models).

We’ll be taking a closer look at buffer batteries, battery storage, charging times and some dynamo chargers with in-built batteries in this article.

Pass-Through Batteries

Most batteries will either charge OR send their stored power to your device; rarely will they do both simultaneously.

Pass-through batteries are able to deliver power from your hub straight to your device, while also taking a charge if there’s any power leftover.

The reason many battery manufacturers don’t allow pass-through is that it can deteriorate batteries quickly, although you can still expect a minimum of 500 total charge/discharge cycles with most pass-through batteries (two half charges equate to one full cycle).

It’s worth noting that many manufacturers include “pass-through” as a feature on the battery spec sheet, but in my experience, this is rarely the case.

Battery Storage Losses

When power is stored in a battery, it experiences a storage loss of 15-20%. In order to minimise this loss, it is best to try to charge your electronics either straight from the USB charger or by using a pass-through battery. It’s nice to have that power on tap, but when it means you lose 1-hour of power per 5-hour ride… it adds up.

Lipstick Buffer Batteries

Batteries are getting smarter circuitry in order to reduce long-term deterioration. But not all batteries are smart!

Jesse Carlsson and Sarah Hammond use the cheapest lipstick batteries they can find to keep a constant stream of power running to their Garmin eTrex GPS units. It’s not guaranteed that the cheapest batteries will be ‘dumb’ enough to allow pass-through, but the odds are good and given they’re less than $10 – it’s worth giving them a go.

Check out Jesse and Sarah’s video on how to waterproof these cheap buffer batteries in their video HERE.

Variable Current Buffer Batteries

If lipstick batteries are dumb, variable current buffer batteries are smart!

A current limiting buffer battery is designed for dynamo hub charging, allowing you to switch between set charging currents (eg. 100, 400 or 900mA) for different riding speeds.

The main advantage is that you can optimise your charging current so that your battery can draw a charge at really low speeds (eg. 6-8km/h). This kind of feature is also handy for charging with solar panels in low-light conditions.

If you’re riding at higher speeds, however, these batteries are less useful because they limit your charging potential to 4.5-watts (many modern dynamo chargers will charge at between 5 and 7-watts once you hit 20kph).

You can see the power graphs for different dynamo USB chargers HERE.

Soshine E4S Battery Kit

This buffer battery kit has been recommended by Velogical, who make rim dynamo charging systems.

The E4S requires 2x 18650 Li-ion batteries (sold separately) to complete the kit. Velogical recommends Samsung INR 18650-29E batteries.

Make sure to pre-charge the buffer batteries using a regular USB charger with a type-B plug.

How Long Will A Battery Take To Charge?

To understand this section well, you may need to learn about volts, amps and watts HERE.

A 3-watt dynamo hub will put out an average of around 6-volts at 500mA. Once the power has been converted from AC to DC the output will translate to roughly 5V and 500mA (or 2.5 watts), which for an hour of riding is 500mAh. Charging a 3000mAh battery from scratch will, therefore, equate to 6 hours of riding at 12km/h with the most powerful USB chargers, and 20km/h with other USB chargers.

However, there are also small losses in the charging circuitry, perhaps around 20% of the total generated power. Adding the 20% extra ride time (6 hours + (6 hours x 0.2)) and we’re looking at 7.2 hours of riding to fill the battery from scratch.

You can also use the above assumptions when determining how long it will take to fill a phone battery. My Apple iPhone SE has a ~1500mAh battery, so at 500mA per hour, it should take 3 hours. Adding in the circuitry losses and I’m looking at 3.6 hours of riding to fill it up. Other modern smartphones like the Samsung S8 will have 3000mAh batteries, resulting in 7 hour + charge times.

Having said all that, there are products which use special capacitors to achieve twice the power, charging smartphones in literally half the time. Many of them also come with build-in buffer batteries. Check out the Cinq Plug5 Plus and Forumslader V5 USB chargers which will achieve 4-5 watts power at just 17-20km/h.

Charging Regular Batteries

You can, of course, charge batteries without pass-through too!

Large capacity batteries (5000mAh+) are great for storing power but can sometimes be problematic to charge as they have more internal resistance in the battery cells. In order to overcome the resistance, bigger batteries require a higher input current (eg. 1A) which is easy for a wall outlet but harder for a dynamo hub at touring speeds. This is why many 5000mAh+ batteries don’t charge particularly well from dynamo hubs.

That said, if you’re cycling at speeds over 25km/h, or you use one of the powerful USB chargers, you can sometimes charge batteries up to 10000mAh – but I’d still recommend 2x 5000mAh batteries instead.

Dynamo Hub Chargers With In-Built Pass-Through Batteries

As dynamo hub charging technology matures, we’re finding manufacturers fitting buffer batteries straight into their chargers. This simplifies the cabling, in particular, making for very neat charging solutions!

You can find integrated buffer batteries in the:
Cinq Plug5 Plus (1100mAh)
Forumslader Ahead (2100mAh)
NC-17 Appcon 3000 (3000mAh)
Lumi-Con P5 (5000mAh)
Busch & Muller USB Werk (300mAh)
ZZing (2000 or 2700mAh)

My full list of dynamo chargers is HERE.

Buffer Battery Recommendations

Soshine E4S 18650 x2 Kit / 5700mAh
Cinq Smart Power Pack II / 3000mAh / 85g – €99 on Cinq
Lipstick Battery (I haven’t tested this battery, but it should do the trick) / 2600mAh / $9.99 on Amazon

Igaro also keeps a list of batteries with pass-through (click the link for the latest):
Blitzwolf – BW-P3, BW-P5 (probably other models in this range)
Miller – ML202 V4
RavPower – Turbo+ RP-PB043
Thrunite – C2
Tomo – M2, M4 (probably other models in this range)
Blackweb – 20,000mAh (Walmart, Adsa)

Check Out Some Of My Other Resources On Dynamo Systems, Dynamo Lights and USB Chargers

The post All About Buffer Batteries With Pass-Through Charging For Dynamo Hub Systems appeared first on CYCLINGABOUT.

Dynamo USB charger technology is actually improving at an incredibly fast rate. Very small companies (ie. often just one person) are designing both hardware and software that exploits the very modest power offered by a dynamo hub. The result is powerful USB chargers that offer high levels of efficiency, that can be neatly fitted to any bike.

This is a pretty technical resource, so strap yourselves in and take it slow. A big focus will be the power output of different chargers at different speeds, but we’ll also look at dynamo hub drag, charger efficiency, form factor and how quickly you can expect your batteries to charge.

This article was originally written September 2017 but has been re-written in July 2019 with the latest information.

Watts, Volts and Amps

Firstly, let’s quickly cover a few basic electricity units of measurement. It’ll take a moment to get your head around this, but the knowledge will help, promise!

Today we’ll be discussing voltage (in volts or ‘V’) and current (in amps, or ‘A’). A common analogy for these units of measurement is in terms of a water pipe. Voltage is the water pressure and current is the flow rate. By increasing the water pressure in a pipe, you will increase the flow rate too. It’s the same with electrical systems; increasing the voltage increases the current.

Watts (W) is the total electrical system power, equal to the voltage (V) multiplied by the current (A). The equation is, therefore:
Watts (W) = Volts (V) x Amps (A).

A 3-watt dynamo hub will put out 6 volts at 0.5 amps (3W = 6V x 0.5A) in AC power. Once the power is converted to DC it’s more like 5V and 0.5A, which is the power required for USB charging. While some USB chargers will start charging at lower rates of power, most devices like to charge above 2-watts (5V x 0.4A) to ensure the charging level is stable.

2-watts can be reached by the best dynamo USB chargers at speeds between 11-13kph. If you’re cycling at lower speeds for short periods of time, a buffer battery will need to be incorporated into your charging system to help meet the power needs of your device. And when cycling for long periods of time below 11-13kph, you’ll need to look to other charging solutions (solar or power banks are usually best for off-road bikepacking).

Most dynamo USB chargers use chipsets with a current limit to prevent overheating (eg. Sinewave Revolution is 1A, therefore the maximum power is about 5W (5V x 1A)). It can be said that any USB charger that puts out high watts will also be putting out a high current.

The Most Powerful Dynamo USB Chargers

Fahrrad Zukunft has conducted some very extensive testing over the years that determines the amount of power (in watts) that can be produced by various dynamo USB chargers. The three below charts (2016, 2016 and 2019) compare 13 different models.

To put the below numbers in perspective, consider that a smartphone consumes around 3-4 watts in navigation mode with full-screen brightness. Therefore, just to keep the battery at the same level will require cycling speeds of 15 to 25kph depending on the model of USB charger. Even then, there’s only a handful of products that generate enough power for this activity.

Let’s take a look at the numbers.

The graphs above show the output power at the USB port at various cycling speeds. You’ll notice that most power curves are rather linear from 5kph until they plateau somewhere between 20-40kph. The exception is the Forumslader V5, which uses a special series of capacitors to boost the power potential of a dynamo hub at low speeds.

Power at different speeds:
1 Watt – Most chargers will hit 1w between 7-10kph.
2 Watts – At 11kph the highest performing charger hits 2w (Plug5 Plus). Most other chargers will hit 2w between 12-15kph
3 Watts – At 14kph the highest performing charger hits 3w (Plug5 Plus). Other chargers hit 3w between 15-25kph
4 Watts – At 17kph the highest performing charger hits 4w (Plug5 Plus) – Other chargers hit 4w between 27-28kph
5 Watts – At 20kph the highest performing charger hits 5w (Forumslader) – Some chargers hit 5w above 35kph

The top-performing chargers:
Cinq Plug5 Plus – 2w@11kph, 3.5w@15kph, 4.5w@20kph, 5w@25kph – Best for sub-20kph speeds
Forumslader V5 – 2w@12kph, 3w@15kph, 4.75w@20kph, 6.5w@25kph – Best for above-20kph speeds
Lumi-Con P5 – 2w@12kph, 3w@15kph, 4w@20kph, 4.25w@25kph
Dynamo Harvester Plus – 2w@14kph, 2.5w@15kph, 4.5w@20kph, 6.25w@25kph

Igaro has recently published some non-independent results for a few missing chargers. These numbers don’t perfectly align with Fahrrad Zukunft, but they are within 10% when examining the Sinewave Revolution. The x-axis is measured in amps, but we can use the equation to convert amps to watts by multiplying by 5 (volts).

Here are some quick conversions:
10kph – Igaro D2 (1.1w), E-Werk (0.9w), Sinewave (0.9w)
15kph – Igaro D2 (2.5w), Igaro D1 (2w), kLite (1.75w), Sinewave (1.75w), E-Werk (1.75w)
20kph – Igaro D2 (4w), Igaro D1 (3w), kLite (2.75w), Sinewave (2.75w), E-Werk (2.75w)
25kph – Igaro D2 (5.2w), Igaro D1 (3.75w), kLite (3.5w), Sinewave (3.5w), E-Werk (3.5w)
30kph – Igaro D2 (6w), Igaro D1 (4.75w), kLite (4.5w), Sinewave (4.5w), E-Werk (3.5w)

Dynamo Hub Drag

There is no such thing as free energy! Do you want a powerful charging system? Ok, well you’re going to have to pedal a bit harder for it. Let’s take a look at dynamo hub ‘drag’ from using different charging systems.

The charts above show the power created at the dynamo hub by different USB chargers. The efficiency of a high-quality dynamo hub at low power (eg. cycling at 10-20kph) works out to be around 50-60%. This means that when the charger is making between 1-3 watts you can roughly double that figure to work out the drag (in watts) at the hub.

Therefore, when making 2.5 watts for USB charging, you’re using about 5 watts of your pedalling power. That drag equates to ~0.4kph slower riding speeds than if you weren’t charging (80kg rider / 15kg bike and gear / 150 watts / flat road). Or a ~3-minute time penalty over a 100km ride.

The efficiency increases to 70-80% at high power (ie. cycling at 30kph). This means that a charger like the Forumslader V5 will be taking 15-watts from your pedalling power while charging at 10.5 watts. That drag equates to ~1.1kph slower riding speeds than if you weren’t charging at 10.5 watts (80kg rider / 15kg bike and gear / 150 watts / flat road). Or a ~9-minute time penalty over a 100km ride.

That’s a decent chunk of time, so it’s in the best interests of charger manufacturers to make efficient units that don’t create too much power, or the drag becomes particularly noticeable when riding.

Power Banks & Charging Batteries

Once you drop below around 2-watts, a dynamo charger will not be able to provide power to most devices. But luckily, some chargers have integrated buffer batteries that will swoop in and provide the power needed for low-speed riding. For this feature, check out the Cinq Plug5 Plus, NC-17 Appcon 3000, Lumicon P5, Forumslader V5 and B&M USB-Werk.

Charging Batteries or Power Banks
If your speed is regularly dropping above and below 11-13kph, it’s best to charge into a power bank for later use. But this is not the most efficient way to keep your devices charged because there are energy losses in the additional circuitry. When power is stored in a battery, it experiences a storage loss of around 15-20%. This means you lose around 1-hour of power generation per 5-hour ride, which adds up!

If you’re cycling faster than 11-13kph, make sure to minimise this loss in efficiency by charging your electronics either straight from the USB charger or by using batteries with a ‘pass-through’ feature (the Cinq Smart Power Pack is the best available).

How Long Does It Take To Charge A Battery?
This depends on the dynamo USB charger and your cycling speed. Let’s take a look at two different power outputs.

Example One: 2.5-Watts (12.5kph on the Cinq Plug5 Plus)
Once a 3-watt dynamo hub has been converted from AC to DC the output will translate to roughly 5V and 0.5A, which for an hour of riding is 500mAh. Charging a 5000mAh battery will, therefore, equate to 10 hours of riding. However, when we factor in the small losses in the charging circuitry, we lose around 20% of the total generated power. Adding the 20% extra ride time (10 hours + (10 hours x 0.2)) and we’re looking at 12 hours of riding to fill the battery from scratch.

Example Two: 4-Watts (17kph on the Cinq Plug5 Plus)
If we use fancy circuitry to boost the output power to 4-watts (5V and 0.8A), we can fill a 5000mAh battery in 6.25 hours of riding. When we account for the ~20% losses in the charging circuitry, this results in 7.5 hours of riding to theoretically fill the battery from scratch.

You can usually find out the battery size of your USB device in the product specifications or written on the battery itself. Read more about power banks and buffer batteries in my resource HERE.

20-Minute Charging Test

While the graphs above give us an idea of the power output at specific speeds, in the hills, it is unusual to cycle at a constant speed for long periods of time. To help simulate hilly or undulating riding conditions, Fahrrad Zukunft created a dynamic test with varied cycling speeds to see which dynamo USB chargers could generate the most power. The test is probably a little over the top in speed variation, but it’s still pretty interesting to see the losses in the charging circuitry.

The test changed the cycling speed in 2-second steps from 10kph up to 30kph and then back down to 10kph again. The accelerations between steps took 3-seconds. This 20-minute test essentially exposes the responsiveness of the microcontrollers inside the chargers, which are constantly trying to optimise the output power at different cycling speeds.

Output power at the USB port after 20 minutes:
1. Forumslader V5 (1200mWh or 240mAh)
2. Lumi Con P5 (1000mWh or 200mAh)
3. Plug5 Plus (1000mWh or 200mAh)
4. NC-17 Appcon 3000 (900mWh or 180mAh)
5. USB Werk (600mWh or 120mAh)
6. Zjego (400mWh or 80mAh)

The test also shows differences in charging efficiency. The bigger the difference between the mWa at the dynamo hub and USB port, the more inefficient the charging system. For example, the Zjego turns 1000mWa into only 400mWa in this test, indicating some very big losses in the circuitry (~40% of power retained). On the other hand, the Forumslader V5 retained ~66% of the power created.

Tying this back to battery charging in the previous section, we could expect the Forumslader V5 to charge a 5000mAh battery in 8.33 hours (including losses in the battery circuitry). The Plug5 Plus would take 10 hours. The USB-Werk would take 16.65 hours.

The Neatest Dynamo USB Charging Systems

Steerer Tube USB Chargers
I don’t know about you, but I really appreciate a neat and integrated charging solution – and the steerer tube mounted systems have got to be the best in this regard. I personally use the Plug5 Plus which integrates a 1100mAh buffer battery inside the steerer for cycling at speeds below 11kph. A very neat metal ring seals the USB-C port from the elements when needed.

Check out the Cinq Plug5 Plus, Forumslader V5 Aheadring, Sinewave Reactor and Cycle2Charge V2.

Regular USB Chargers
Ortlieb has a handlebar bag called the Ultimate 6 Pro E which has connectors built into handlebar bag mount. This allows you to keep your USB charger and devices inside your waterproof bag, and take the handlebar bag off without unplugging anything. That just leaves a few wires on your bike – a very neat solution!

Dynamo Light USB Chargers
Here’s another super neat charger design. There are a handful of lights that also incorporate the circuitry for charging USB devices. This creates a very neat (less cabling) and often cost-effective light+charger. That said, some light/chargers are less efficient than standalone units because they are not optimised around charging.

Check out the Sinewave Beacon, Forumslader IQ-X, Axa Luxx70 Plus and B&M Lumotec IQ2 Luxos.

Testing Your USB Charger

If you’re having issues with charging, a cheap USB LCD Voltmeter can help diagnose whether your USB charger is making the right amount of power. If you’ve determined you’re getting the right voltage and current for your device, you may be having issues with the particular cache battery you’re using.

The Best-Performing Dynamo USB Chargers

Cinq Plug5 Plus // Sub-20kph
Most bike travel is conducted at speeds below 20kph (12mph), and the charger that offers the most power at these speeds is the Plug5. Not only is it powerful, but it also integrates a buffer battery into the system for the times you’re cycling below 11kph. The covered USB port is very neat too!

Cinq Plug5 Plus Numbers:
2w @ 11kph
3.5w @ 15kph
4.5w @ 20kph
5w @ 25kph

Forumslader V5 // Above-20kph
The Forumslader V5 uses a special series of capacitors to achieve big power from 20 to 30kph (12-19mph) in particular. It also incorporates buffer batteries (3x700mAh) and a neat USB port near the handlebars.

Forumslader V5 Numbers:
2w @ 12kph
3w @ 15kph
4.75w @ 20kph
6.5w @ 25kph

Creating Bombproof Dynamo USB Chargers

Kerry from kLite focuses on building dynamo light and charging systems for remote backcountry use. His main aim is reliability, so his charging systems are as simple as possible, using thick internal cabling, full waterproofing and smoothing capacitors that offer ultra-consistent waveforms (best practice for direct charging; Kerry says they take up half of his charger).

Usually, more complex circuitry and small form factors result in more chance of something going wrong, so it’s always best to hunt around for reviews online to see how different USB chargers are performing in the world’s harshest environments.

List Of Different Dynamo USB Chargers

You can see a list of most hub dynamo USB chargers options HERE.

Summary

The top-tier dynamo USB chargers offer very decent power these days, provided your touring speed is above 11-13kph. Once you hit 15kph with five of the charging units tested, you’ll be generating more than 3-watts which is a very decent charge for most batteries and devices. And by 17-20kph you can generate 4-watts for even the most power-intensive smartphones.

You can neatly integrate a USB charger into your steerer tube, front dynamo light or handlebar bag via the Ortlieb Ultimate 6E connectors. There are lots of great options!

Remember that you increase the dynamo hub drag when generating additional power, but this will be necessary if you’re a heavy electronics user (eg. smartphone navigation with the screen always on). That said, if you just want to keep on top of your phone or GPS, almost all USB chargers will do this job just fine.

Learn About Dynamo Hub Systems HERE, About Buffer Batteries HERE and Dynamo Lights HERE

The post All About The Best Dynamo USB Chargers For Bicycle Touring and Bikepacking appeared first on CYCLINGABOUT.

There are only a handful of dynamo hubs on the market, but there are some significant differences between them. This article will delve into everything you should know about dynamo hubs.

Dynamo Hub Types

Axle Sizes

The most common size for a touring bike is still 9mm quick release, but with axle standards changing both on-road and off-road, we’re now finding touring and bikepacking bikes available with six axle variants.

1. Quick Release 9mm – 100mm
2. Thru Axle Road 12mm – 100mm
3. Thru Axle MTB 15mm – 100mm
4. Thru Axle MTB Boost 15mm – 110mm
5. Fat Bike Quick Release – 135mm
6. Fat Bike Thru-Axle 15mm – 150mm

Connectors

There are two different common forms of spade connector – the Shimano design and the Schmidt SON design. Neither design can be said to be ‘better’ – they both do the same job of transmitting power up the cable. Due to the market split of connector types, dynamo lights and USB chargers tend to come without any connector attached to the cable ends.

A less common connector design is the Schmidt SL fork dropout. This is a really neat design; the connection happens between the edge of the hub and a fork dropout plate that’s soldered to the wiring. Almost every Schmidt hub is made in an SL version. Unfortunately, you’ll rarely find the Schmidt SL dropout on anything but custom-built forks.

Power Specification

There are three different power specifications for dynamo hubs: 1.5-watts, 2.4-watts or 3-watts (all at 6-volts). Given that touring and bikepacking is often conducted at speeds below 25KPH/15MPH, the most powerful option (3W) is necessary for charging USB devices, and it’s the best for low-speed lighting too. That said, 2.4W hubs offer enough power if you’re touring using smaller diameter wheels (16-20″) and 1.5W hubs are appropriate for lighting your way at higher speeds (ie. 25KPH/15MPH).

Spoke Count

Dynamo hubs come with anything from 20 spoke holes for a lightweight carbon wheel builds through to 48 holes for the strongest tandem wheel. Most touring and bikepacking bikes use between 28 and 36 spokes. While spoke count makes some difference, evenly balanced spoke tension across the wheel and a stiff touring rim tend to matter most in terms of strength.

Performance: Dynamo Hub Power Output

At different speeds, dynamo hubs offer varying amounts of power for your lights and USB chargers. The amount of power a dynamo hub delivers will depend mostly on the light or USB charger – but there are also a few tricks dynamo hub manufacturers use to boost their power outputs.

Dynamo hubs paired with powerful USB chargers will provide smartphone levels of charging from about 12KPH (look for 2.5W on the graph). That said, some hub and charger combinations will not deliver 2.5-watts until around 20KPH.

When we compare the power outputs at different speeds for the kLite USB charger (see graph above), you’ll notice the green line of the Shimano UR700 is offering the most power at all speeds, and the red line of the SP PD-8 the least. At 15KPH the UR700 is delivering three times the power output – quite significant considering the hubs both have the same 3W power specification.

That said, if you want high power outputs from your dynamo hub, you have to pay for it with additional drag.

Performance: Dynamo Hub Drag

If you’ve ever picked up a dynamo hub and tried to spin the axle, you’ll know that they feel incredibly ‘notchy’. This is the result of a series of powerful magnets passing a coil and in turn, creating an electric charge. With no light or USB charger connected, this drag only has a small effect on your speed because of the flywheel effect of a rotating wheel. According to the graph above, the drag is between 1 and 5-watts depending on the cycling speed and hub model.

When you connect a light or charger to the hub, the drag will increase. The amount of drag is mostly a function of the light or USB charger that you have connected, but there are variations between hubs too. The graph above shows how four different dynamo hubs perform with the brightest dynamo light currently available, the kLite Bikepacker Ultra. As you can see, the drag increases with the output power and speed. At maximum brightness when using the SP PD-8 hub (25KPH), the drag at the hub is around 24.5-watts, which is likely to be somewhere between 12-20% of your total pedal power. That’s a lot.

You can read the full dynamo hub testing analysis HERE.

Performance: Dynamo Hub Efficiency

A more efficient hub will turn more of your pedal power into power for your lights or charger. We can find out how efficient a dynamo hub is by comparing its power output and drag at different speeds.

The rate of efficiency is quite different for different hubs. For example, at 15KPH a Schmidt SON28 hub provides 1.9-watts to your USB device but will take 3.2-watts of your pedal power (see graph above). That means 59% of the SON28 resistance will be going towards charging your device. In comparison, the SP PD-8 will create 0.9-watts but will take 4.6-watts. In this case, only 20% of the PD-8 resistance will go to charging your device.

Charging Test Averages (Four Different Chargers):
1. SON28 Hub – 57% efficient
2. 3D32 Hub – 44% efficient
3. UR700 Hub – 39% efficient
4. PD-8 Hub – 34% efficient

Lighting Test Averages (Four Different Dynamo Lights):
SON28 Hub – 44% efficient
3D32 Hub – 37% efficient
PD-8 Hub – 31% efficient
UR700 Hub – 30% efficient

You can read the full dynamo hub efficiency results HERE.

Schmidt SON Dynamo Hubs (3W)

Schmidt is the industry standard for dynamo hubs in terms of both efficiency and reliability. These German-made hubs are also the most expensive. Despite this, they’ve been my dynamo hubs of choice since 2008. The bearings are not expected to need servicing until well after 50,000km due to a combination between robust weather sealing and the high-quality SKF sealed bearings (I’ve never actually had to replace the bearings in any of my hubs). Included with Schmidt hubs is a five-year guarantee too.

Schmidt hubs have been tested to have the lowest resistance without a device or light connected – just 1.4 to 1.9-watts of resistance (10-30KPH). And with a light or USB charger connected, they generate the lowest drag of all hubs, resulting in a charging efficiency of 57% and a lighting efficiency of 44% on average.

Quick Release
SON28 non-disc – 32, 36h
SON28 disc – 28, 32, 36h
SON28 Tandem – 40, 48h
SON28 disc 135 – 32h
SON28 disc 135 VR – 32h

Thru Axle – Disc
SON28 12mm – 28, 32, 36h
SON28 15mm – 28, 32, 36h
SON28 15mm Boost 110 – 32, 36h
SON28 15mm 150 – 32h

Shutter Precision SP Dynamo Hubs (3W)

SP dynamo hubs are the lightest dynamo hubs available and are also quite modest in price. The latest generations are known to be very reliable, but unfortunately, they’re not the best performers – they have a lower rate of efficiency and power output compared to other hubs. That said, SP makes some unique hub configurations you won’t find elsewhere, including for road bikes with a low spoke counts (20 and 24-hole). In addition, their 15mm thru-axle hubs are literally half the cost of a Schmidt. SP gives you the choice between brake rotor mounts on many hubs: 6-bolt (eg. PD-8X) or centerlock (eg. PL-8X).

Quick Release
PV-8 non-disc – 20, 24, 28, 32, 36h
PD-8 disc – 20, 24, 28, 32, 36h

Thru Axle – Disc
PD-8X-M 12mm – 32, 36h
PD-8X 15mm – 32, 36h
PD-8X-110 15mm – 32, 36h
PD-8X-150 15mm – 32, 36h

Shimano Dynamo Hubs (3W)

Shimano makes the majority of the world’s dynamo hubs, so it’s safe to say that they know a thing or two about them. Shimano hubs are very reliable, serviceable and usually the cheapest too. On top of that, they’re brilliant performers. The latest model, the UR700, is the most powerful dynamo hub available (highly recommended for off-road or hilly regions), while the rest of the hubs work out to have the second-best charging and lighting efficiency.

The Deore LX and Alfine models are essentially the same, while the Deore XT dynamo hub sheds 56 grams thanks to an aluminium axle and coil. The top-of-the-line dynamo hubs (UR700 and UR705) save a further 30-50 grams.

Quick Release
Alfine S501 disc – 32, 36h
Deore LX T670 non-disc – 32, 36h
Deore LX T675 disc – 32, 36h
Deore LX 3N72 non-disc – 32, 36h
Deore LX 3D72 disc – 32, 36h
Deore XT T8000 disc – 32, 36h
UR700 disc – 32, 36h

Thru Axle – Disc 
UR705 12mm – 32, 36h

KT Dynamo Hubs (3W)

KT has recently released a dynamo hub range including a hub with a rather innovative end-cap design. By switching out the end-caps, you’ll be able to interchange your dynamo wheel between bikes that employ QR, 12mm or 15mm axles. You can get the hub in either the standard 100mm hub width or to suit 110mm Boost forks, and the disc brake hub models are available with 6-bolt (eg. KD5F) or a centerlock (eg. KC5F) brake rotor mounts. KT hubs employ the same hub shell as the SP Dynamo hubs, although internally they have their own circuitry which is yet to be tested for output power, drag, efficiency or long-term reliability.

Quick Release
KD6F disc – 32, 36h
KV6F non-disc – 32, 36h

Thru Axle – Disc
KD5F 9mm 12mm 15mm – 28, 32, 36h
KD1F 9mm 12mm 15mm Boost 110 – 28, 32, 36h

Note: the KT KD5F Dynamo is rebranded under the manufacturer “TFHPC”.

Kasai Dynamo Hubs (3W)

Kasai has released a hub called the FS Dynacoil. While most dynamo hubs are sealed at the factory and cannot be repaired yourself, this dynamo is field serviceable. Using a 36mm flat wrench, you have access to both the coil assembly and hub bearings. That means that if your hub stops providing power, you can replace the coil assembly yourself (hopefully under warranty) without having to re-lace a new wheel. In addition, when your sealed bearings inevitably wear out, you can replace them too.

Like the KT hub, we don’t yet have any idea how durable the Kasai is, along with its output power, drag or efficiency data – but Kasai is claiming 72% efficiency at 10mph (likely using a resistor). The hub weighs between 445 and 495 grams depending on the model.

Quick Release
Dynacoil FS non-disc – 32h, 36h
Dynacoil FS disc – 32h, 36h

Thru Axle – Disc
Dynacoil FS 15mm Center Lock – 32h, 36h
Dynacoil FS 15mm 6-Bolt – 32h, 36h

Other Dynamo Hubs (3W)

Biologic Joule 3 Disc – Re-branded 32h Shutter Precision PD-8 hubs in silver or black.
Exposure Disc – Another re-branded 32h SP PD-8 hub available in a package with the Exposure Revo dynamo light.
Love Mud Juice Disc – More re-branded 32h SP PD-8 hubs!
Neco Rove Disc – The claims are pretty lofty for this 933g dynamo hub with built-in USB charger – 15W of charging potential (5V@3A). Unfortunately, the testing has shown that you need to be going 50KPH to achieve that figure and that it isn’t at all competitive below 25KPH.
Sanyo H27 Non-Disc – This is one of the best value dynamo hubs going around. Unfortunately, it has a lot of drag compared to other hubs, even with lights or USB chargers switched off.

Learn About Dynamo Hub Systems HERE, About Buffer Batteries HERE, About USB Chargers HERE and Dynamo Lights HERE

The post How To Choose The Best Dynamo Hub for Bicycle Touring and Bikepacking appeared first on CYCLINGABOUT.

Let’s start with a component map to understand how everything pieces together. 

Hub Dynamo System Map

Dynamo Cabling

Spade Connectors

Most dynamo hubs spit out their power via two spade connectors at the axle.

There are two different common forms of spade connector – the Shimano design and the Schmidt SON design. Neither design can be said to be ‘better’ – they both do the same job of transmitting power up the cable. Due to the market split of connector types, dynamo lights and USB chargers tend to come without any connector attached to the cable ends.

A less common connector design is the Schmidt SL fork dropout. This is a really neat design; the connection happens between the edge of the hub and a fork dropout plate that’s soldered to the wiring. Unfortunately, you’ll rarely find the Schmidt SL dropout on anything but custom-built forks.

Fitting Schmidt Hub Spade Connectors

A crimper tool is an ideal way to fit Schmidt spades to bare wires. With a good crimping, the dynamo cable will look neat and be fixed very firmly to the spade. It’s a really good idea to use a bit of heat shrink over the spades to protect them against the elements (they can corrode). At a pinch, I’ve used a pair of pliers to connect spades, but you won’t get that nice spade curl without a crimper.

Piggyback Spade Connectors

One advantage to the Schmidt spade design is that you can use ‘piggyback’ spade connectors at the hub. These connectors have a second set of spades built in, allowing you to connect two extra wires (ie. your USB charger) to the system.

Wiring both lights and a charger simultaneously is not a problem provided there is an on/off switch on the light (or charger). This is because piggyback connectors will send power to both your light and USB charger. Unfortunately, there’s not enough power to run your lights at full brightness AND get a decent charge, so you can use the light ‘off’ switch to divert 100% of the power to the USB charger, or you can unplug devices from the USB charger with the lights ‘on’ for maximum illumination.

Splicing Cables

If you’re using the Shimano connector design, the best way to get power to both your lights and USB charger is by splicing the four cables together. This will produce a single set of cables with spade connectors at the end. Again, you’ll want to make sure that your dynamo front light (or USB charger) has an on/off switch because like piggyback connectors, spliced cables send power everywhere.

Dynamo Two-Way Switches

If your front light (or USB charger) does not have an on/off switch, you’ll want to incorporate a two-way switch elsewhere into your system. Two-way switches send 100% of the power from your hub to either your light or charger. Switches also allow the physical size of a dynamo light to be greatly reduced. Check out two-way switch products from Igaro and kLite.

Breaking Cables

There are a few ways to ‘break’ your cables. You may need to do this to extend the length of a dynamo cable, or perhaps it will help with removing components of your system when packing a bike into a box. I like to keep my system as modular as possible!

I use the ultra-neat Supernova Gold Connectors (US $16) in order to disconnect my rear light from my front. Alternatively, Schmidt makes some small and highly cost-effective 2.8mm spade connectors for a fraction of the price (US $0.20) which essentially do the same job.

A more recent development are Dyna-Snap magnetic connectors. Using magnetic cable ends, you can disconnect parts of your dynamo system in an instant. An obvious advantage to this system is for easy front wheel removal. As there’s no delicate spade-locating required, the magnetic connectors can automatically find each other when in proximity.

Buffer Batteries

The power from a dynamo hub will drop too low for charging when your speed is below ~12km/h. GPS devices tend not to like this, displaying a rather annoying ‘lost external power’ message whenever you stop or slow down. Smartphones also don’t enjoy charging on a varying voltage, so to get the most out of your charging system you should plug a buffer battery into the USB charger, and your phone/GPS into the battery.

At higher speeds, the battery will store power which will be used to keep a constant power supply for your GPS/phone at the low speeds or when stopped. A buffer battery with power passing directly from input to the device has no loss in efficiency. But when the power is stored in the buffer battery rather than being used straight away, that’s where you will experience a loss of 15-20%.

There are a few things to note about getting a buffer battery. Some larger batteries (10000mAh+) will have a minimum current input of 1A, while most USB chargers will be delivering 0.5A for the majority of the time. This renders those batteries incompatible. You will also need to find a battery that can be discharged while it’s getting charged (‘pass-through’ charging). Lots of battery manufacturers will not permit ‘pass-through’ charging because it limits the lifespan of a battery. The best source for pass-through batteries is often through solar power kit manufacturers.

To learn everything about buffer batteries click through to my battery resource HERE.

Combined Light and Dynamo Units

There’s a few integrated dynamo lights/chargers which are cost-effective and elegant as they incorporate all of the electronics, including a switch, into the one simple unit. Keep in mind that they don’t include a buffer battery – you’ll have to add one to achieve a constant charge at low speeds for smartphones and GPS devices.

AXA Luxx70 Plus (70 lux) – USB charging, amazing value for money (US $139)
B&M Luxos U (70 lux) – USB charging, handlebar-mounted switch, great beam shape (Amazon Special US $178)
Sinewave Cycles Beacon (750lm) – USB charging, light assist with battery, very high output at low speed. (US $350)

To learn everything about dynamo lights and beam patterns, I recommend clicking HERE.

The Effectiveness of Dynamo Systems

At typical cycling speeds, you will not get a good USB charge and have a decent beam lighting the road – it’s one or the other.

Given the latest LED and lens technology, you can now buy dynamo lights that are over 100 lux or 1200 lumens at 20km/h (12mph). That’s more than enough for everything on the road, as well as most off-road stuff too. Some off-road dynamo lights can have power coming in via a battery for slow riding too (kLite Bikepacker Ultra, Sinewave Beacon).

You can achieve a decent charge at relatively low speeds with many of the USB chargers. This is enough to charge a phone or GPS in a few hours provided your speed doesn’t drop below 12-15km/h.

In terms of electrical resistance, you can expect to lose about 5 watts of pedalling power with your dynamo system on, and 0.25-1.00 watts when it’s off (when compared to a regular front hub). Click HERE to read all about dynamo hub efficiency and the effect on your riding speed.

Summary

Building a hub dynamo system takes a little bit of know-how, but it’s quite straight forward once you’ve got the basics.

I generally recommend starting with a dynamo hub, front light (with an on/off switch) and a USB charger. Either splice your cables together (Shimano design) or fit up piggyback spade connectors (Schmidt design) to get everything wired up neatly. Try to put a few cable ‘breaks’ in your system to keep it modular – especially if you’re planning on taking sections off your bike (fork, rack etc) for both flights and general bike mods.

Example high-performance system on a budget:
– Shimano UR705 disc dynamo hub (Amazon Special US $120)
– The Busch + Müller Eyc T 50lux light (Amazon Special US $74)
– The Kemo M172N USB charger (US $50)
– Optional: Cinq 5 Smart Power Pack II 3000mAh battery with variable 100/450/900mA current (€99)
Total: US $244

Example all-out system:
– Schmidt SON 28 dynamo hub (US $265)
– Schmidt Edelux II light (US $176)
– Cinq Plug5 Plus USB charger including buffer battery (€259/$289)
Total: US $730

There’s so much more to know about dynamo light beam patterns and USB chargers. Have a hunt around the site and you can find out much more information on it all.

Click HERE To See The Different Dynamo Hub USB Chargers Available and HERE To Learn All About Dynamo Lights

The post How To Set Up The Best Hub Dynamo System For USB Charging & Lights appeared first on CYCLINGABOUT.

But where does this energy come from, and to what extent does it slow us down?

If you’ve ever picked up a dynamo hub and tried to spin the axle, you’ll know that they feel incredibly ‘notchy’. This is the result of a series of powerful magnets passing a coil and in turn, creating an electric charge.

The writers at FahrradZukunft put together some lab tests a few years ago to find out more about dynamo hub drag. Let’s take a look at their testing, the data and then draw some conclusions about the effect of dynamo hub drag on our speed.

Note: This article has been superseded with new data and calculations presented HERE.

The Lab Test

The different dynamo hubs were clamped into a lathe and spun to different speeds. The speed was determined simply by measuring the frequency of the generator with the known number of pole pairs. A supporting load was applied to the opposite end of the hub to replicate the downward force of a fork, and a 12-ohm electrical load resistor is connected to replicate a standard dynamo lighting system. With everything set up, the drive power is then calculated.

The Results

Light Switched OFF While Cycling @ 10-30km/h
Schmidt SON28 // 0.25w-1.25w drag
Schmidt SONdelux // 0.25w-1.25w drag
SP Dynamo PV8 // 0.50w-1.75w drag
Shimano DH-3N80 // 0.50w-2.50w drag
Sanyo H27 // 1.00w-6.00w drag

The lowest drag hubs with the light switched OFF are the SON hubs. They’re rolling almost as efficiently as a regular hub despite having the dynamo infrastructure. The SP Dynamo hub is the next most efficient, followed by the Shimano DH-3N80 hub. The Sanyo H27 is clearly the least efficient dynamo hub and was almost 5x less efficient than a Schmidt hub at 30km/h.

Light Switched ON While Cycling @ 10-30km/h
Schmidt SONdelux // 2.50w-6.50w drag
SP Dynamo PV8 // 2.75w-7.00w drag
Schmidt SON28 // 3.00w-6.50w drag
Sanyo H27 // 3.75w-7.25w drag
Shimano DH-3N80 // 3.50w-7.50w drag

The lowest drag hub is the SONdelux. Next is the SP Dynamo which achieves a marginally lower drag than the SON28 at 10km/h, but is 0.5w higher at 30km/h. The Shimano DH-3N80 performs well at slower speeds, but is the least efficient hub option at 30km/h. The Sanyo H27 is surprisingly efficient when switched on, in fact, it’s MORE efficient than the more expensive options at high speeds!

Other Comparable Data

Schmidt has conducted their own testing for the SONdelux, SON28 and Shimano DH-3N80 hubs. The results fall very closely in line with the independent testing conducted by FahrradZukunft, but their data shows slightly less drag on all three hubs between 10-30km/h. This could be due to a different electrical load applied to the hubs.

Light Switched OFF While Cycling 10-30km/h
Schmidt SONdelux // 0.25w-1.00w drag
Schmidt SON28 // 0.25w-1.50w drag
Shimano DH-3N80 // 0.50w-2.00w drag

Light Switched ON While Cycling 10-30km/h
Schmidt SONdelux // 1.80w-6.10w drag
Schmidt SON28 // 2.15w-6.50w drag
Shimano DH-3N80 // 2.30w-7.25w drag

The Effect On Your Speed

We now have an idea of the numbers, but how does this translate in terms of speed?

Let’s compare two different rider weights (60 and 80kg) and gear weights (15kg and 30kg). I’ll adjust the power (effort) to be more in line with each of those rider weights too (100w and 150w). We can assume the drag of a non-dynamo hub is 0.5 watts. I’ve taken the dynamo hub drag at the different speeds and subtracted 0.5 watts in order draw a direct comparison.

The calculations have all been done with BikeCalculator.com which I’ve found to be very accurate from prior testing.

60kg rider / 15kg Bike and Gear / 100 watts / Non-Dynamo Hub = 24.34km/h.
Most efficient hub: off – 24.29km/h (0.5w extra drag) +0.2%
Least efficient hub: off – 23.94km/h (4.0w extra drag) +1.6%
Most efficient hub: on – 23.82km/h (5.25w extra drag) +2.1%
Least efficient hub: on – 23.71km/h (6.25w extra drag) +2.6%

60kg rider / 30kg bike and gear / 100 watts. Non-Dynamo Hub = 23.83km/h.
Most efficient hub: off – 23.78km/h (0.5w extra drag) +0.2%
Least efficient hub: off – 23.42km/h (4.0w extra drag) +1.7%
Most efficient hub: on – 23.29km/h (5.25w extra drag) +2.3%
Least efficient hub: on – 23.19km/h (6.25w extra drag) +2.7%

80kg rider / 15kg bike and gear / 150 watts. Non-Dynamo Hub = 27.96km/h.
Most efficient hub: off – 27.92km/h (0.6w extra drag) +0.1%
Least efficient hub: off – 27.60km/h (4.75w extra drag) +1.3%
Most efficient hub: on – 27.53km/h (5.75w extra drag) +1.5%
Least efficient hub: on – 27.46km/h (6.60w extra drag) +1.8%

80kg rider / 30kg bike and gear / 150 watts. Non-Dynamo Hub = 27.51km/h
Most efficient hub: off – 27.47km/h (0.6w extra drag) +0.2%
Least efficient hub: off – 27.15km/h (4.75w extra drag) +1.3%
Most efficient hub: on – 27.07km/h (5.75w extra drag) +1.6%
Least efficient hub: on – 27.01km/h (6.60w extra drag) +1.8%

The Effect On Your Riding Time

Using the speed data, we can work out how drag translates in terms of time:
– The most efficient dynamo hubs when switched OFF add between 17 and 30 seconds to a flat ride over 100km when compared to a regular hub.
– The most efficient dynamo hubs when switched ON add between 3min 24sec and 5min 47sec to a flat ride over 100km when compared to a regular hub.

Does Dynamo Hub Drag Really Matter?

Only a little.

To put dynamo hub drag into perspective we can compare the 1.5-2.7% slower speeds with a:
– 7.9% slower cycling speed when using four panniers as opposed to bikepacking bags
– 5.4% slower cycling speed when using Schwalbe Marathon Mondial tyres as opposed to Schwalbe Almotion
– 3.2% slower cycling speed when carrying 30kg extra luggage on a flat road

Given the leverage of a wheel and the flywheel effect of the rotating mass, dynamo hub drag only has a small effect on your speed. The result for most people is likely to be an extra three to six minutes riding time over 100km, all while getting a good charge to your electronics (or while running lights).

On CyclingAbout, you can also learn about: 
The Best Dynamo USB Chargers
The Best Dynamo Lights
The Best Buffer Batteries For Dynamo Systems
How To Set Up A Dynamo System

The post How Much Does Dynamo Hub Drag Really Slow You Down? Lab Testing Results appeared first on CYCLINGABOUT.