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Gearboxes are becoming more and more popular on touring and bikepacking bikes. The most common form of bicycle gearbox is the internal gear hub, which has been available since the late-1800s. The earlier hubs were a two-speed design, but these days we have the 14-speed Rohloff hub as our benchmark.
More recently you can find mid-mount gearboxes on touring bikes. The Pinion 18-speed gearbox is growing in popularity and is now found on touring bikes from more than 100 manufacturers.
While there is usually a weight penalty to gearbox systems over derailleurs, this is negated by how easy they are to maintain, especially in poor cycling conditions. But let’s put the pros and cons of gearboxes aside for a second.
What I want to know is the difference in drivetrain efficiency between gearbox systems. With this data, I can then analyse the speed differences between different gearboxes.
The Test
Andreas Oehler from online magazine FahrradZukunft conducted his own testing to find out the drivetrain efficiency between gearboxes, using a single-speed drivetrain as a benchmark. You can read the full internal hub test HERE and the internal crank test HERE.
Two different test rigs were set up to measure both internally geared hubs and internal crank gearboxes. The cadence (pedalling speed) was set up at 60 RPM which provided the most consistent data. A low-tension lubed chain was used to drive the wheel and the same front chainring was used for each test.
Two different power rates were tested, 50 watts and 200 watts; the low power was used to get a sense for the idle losses at the gearbox.
Results
While the data from the graph indicates the drivetrain efficiency for each gear, I’ve averaged out the drivetrain efficiency across each gear range to come up with the following numbers:
Singlespeed: 97% efficient (Drivetrain loss of 6w @ 200w).
Rohloff : 94.5% efficient on average across 14 gears (Drivetrain loss of 11w @ 200w)
Pinion: 90.5% efficient on average across 18 gears (Drivetrain loss of 19w @ 200w).
Shimano Alfine 11: 90.5% efficient on average across 11 gears (Drivetrain loss of 19w @ 200w).
Shimano Nexus 8: 90% efficient on average across 8 gears (Drivetrain loss of 20w @ 200w).
Nuvinci 360: 83.5% efficient on average across the gear range (Drivetrain loss of 33w @ 200w).
You can see the Nuvinci 360 testing on this graph.
Analysis
For this article, I will focus on the power rate of 200 watts as it’s in line with my other testing.
At a power rate of 200 watts, there was less than 10 watts difference between the most common gearbox systems (Rohloff, Pinion and Shimano). While seemingly insignificant, this is a similar difference in resistance between a set of touring tyres with an off-road tread (Schwalbe Marathon Mondial) and a set of road touring slicks (Schwalbe Marathon).
The Rohloff hub came out on top, as it’s more efficient in almost every gear than the other gearboxes. Two things are surprising, however; in the direct drive gear (number 11) it’s less efficient than gear 8 despite it engaging more moving parts, and the noisiest gear (number 7) isn’t actually the least efficient. I’m not exactly sure why these may be.
The Pinion P1.18 is the most consistent throughout its gear range. It slightly underperforms when compared the Alfine 11 in the low gears, but has the edge in the higher gears. These two gearboxes average out to have similar efficiency.
The Shimano Alfine 11 gets less efficient as the gears get higher. That means that in the top gear, you’re losing ~15w through drivetrain inefficiencies when compared to the Rohloff. If you do the bulk of your riding in the higher gears (ie. on the flat) you will have the most to lose.
The Shimano Nexus 8 (practically the same as the Alfine 8) has an interesting efficiency graph. It’s quite obvious that gear 5 is the direct drive gear, using 20 watts less than the 4th gear. Given the way the efficiency gradually reduces in two sections, it’s clear the hub engages more internal parts the closer you get to gear 4 and 8.
Pinion P1.18 vs. Rohloff Speedhub Gearbox Systems
There are a few reasons why the Pinion P1.18 is less efficient than a Rohloff hub. Firstly, the chain runs 50% faster in the equivalent gear, so this results in more losses at the chain itself. Secondly, as the gears get higher on the Pinion it engages faster rotating internal cogs, potentially resulting in additional losses. And lastly, the large seals at the crankshaft may also contribute to the losses.
What Is The Speed Difference Between Gearboxes?
When comparing the most and least efficient gearbox systems there’s a 22-watt difference in resistance. This translates to about 1.44km/h (0.89mph) slower travelling speeds using the Nuvinci 360 rather than the Rohloff hub, with all things being equal (200w, 85kg total weight, flat road). Knowing the speed difference, we can determine the time differences over the course of a typical touring day using Bike Calculator*.
On A Flat 100km Route (0% Gradient)
Over 100km, the 1.44km/h drop in speed from the Rohloff to the Nuvinci will add 9 minutes and 30 seconds to your cycling time (4.9% slower). To put that into perspective, carrying 30kg (66lb) extra on your touring bike would add 5 minutes to your ride time (2.6% slower) on the same route.
Over 100km, the 0.51km/h drop in speed from the Rohloff to the Pinion P1.18 will add 3 minutes and 15 seconds to your cycling time (1.7% slower). To put that into perspective, carrying 20kg extra on your touring bike would add 3 minutes to your ride time (1.6% slower) on the same route.
On A Hilly 100km Route (10km up, 10km down x5 @ 2% Gradient)
Assuming it’s hilly, gearbox resistance plays an even greater role because of the lower travelling speeds. The less efficient Nuvinci 360 adds 13 minutes and 20 seconds to your cycling time (5.9% slower) when compared to the Rohloff. To put that in perspective, carrying 15kg (33lb) extra on your touring bike would add 15 minutes and 30 seconds to your ride time (6.9% slower) on the same route.
Over 100km, the less efficient Pinion P1.18 adds 4 minutes and 31 seconds to your cycling time (2.1% slower) when compared to the Rohloff. To put that into perspective, carrying 5kg extra on your touring bike would add 5 minutes to your ride time (2.3% slower) on the same route.
*Through my weight testing, I’ve determined Bike Calculator to be close to accurate.
How Does Gearbox Efficiency Compare To Derailleurs?
Velonews has tested the drivetrain efficiency of both 1X and 2X drivetrains in the lab. As this test was conducted under a different test protocol (higher cadence, higher power output, different measuring equipment etc), these results are not directly comparable – but we can still get some sense for whether gearboxes are drastically less efficient.
In the test, a Shimano Ultegra 2X drivetrain achieved an average of 96.2% drivetrain efficiency, while a SRAM Force 1X drivetrain averaged out at 95.1% efficient. This means that a Rohloff hub likely runs 1-2% less efficient, while a Pinion gearbox or Shimano internal gear hub is 5-6% less efficient, on average.
You can read my analysis of the 1X/2X drivetrain efficiency testing HERE.
Does Gearbox Efficiency Really Matter?
I’ve now looked at the speed difference of gearboxes, gear weight, aerodynamics, tyres and dynamo hubs. Gearbox efficiency can make a significant difference at the extremes (comparing the best and worst performer) but is much more negligible in the scheme of resistance.
At most, a Pinion gearbox or Shimano Alfine 11 hub will cost you five minutes per 100km (2.1% slower) when compared to a Rohloff or derailleur drivetrain. This is similar to the effect of a dynamo hub generator (1-3% slower) when compared to a regular hub.
The biggest speed differences come from tyre rolling resistance and aerodynamics. When comparing fast and slow rolling tyres on flat and hilly 100km courses, we can add between 12 and 17 minutes (5-7% slower) to our ride time. The aerodynamic testing yielded similar results with panniers adding 12 to 18 minutes over 100km when compared to bikepacking bags.
So with this in mind, you’re best to pick one of the gearbox systems based on your budget and whether the gear range offered is suitable for the terrain you ride.
Click HERE To Check Out The Tyre Testing and HERE To See The Aero Testing
Interesting statistics. I’m not sure though if I would ride with an output of 200w for touring or even just a long ride. However relating the minuscule difference in time like that may be beneficial with partners who have already got the tent set up or the cooking started by the time you arrive. At least open a beer for you.
Other considerations, like you stated, is where you’re going to ride. Hills, rain, mud, dust will impact on a drivetrain from minor to major.
The numbers are going to be a little different for everybody. But the difference in time actually gets greater with slightly less power (to a point).
If we run the numbers using an average between the 50-200w for interests sake (125w), we get ~93% efficiency on the Rohloff and ~88% with the Pinion (which is a 6w difference… it would actually be a little less due to idle losses). Anyway, that’s a 4 minute 34 second difference on the flat over 100km with the same rider as in the example above (2.0% slower). On the hilly course, the difference between a Rohloff and Pinion is 7 minutes and 22 seconds (2.7% slower)!
So if anything, riding at less power may make a larger difference in terms of time!
I was looking for such an evaluation for long! Thanks a lot!
It confirms my “feeling” with many electric bikes with the NuVinci – I didn’t like the feeling of the NuVinci. Freewheeling felt always harder, and I didn’t feel attracted at the NuVinci. All I could think of “it feels harder”. The reviews say that the NuVinci has the advantage that I can set whatever gear I want. However, in practice, I had about 6-7 different speeds that I could set, simply the shifter was not precize enough to make small differences.
I would be interested to see an “Overview of Resistance for Bike Touring” type of table or article. Where you add the effects of Hub dynamo, tyres, gears, weight, aero, belt vs. chain, etc. My feeling is that for typical touring the comfort still plays a much larger role in selection, vs. the resistance. It would be nice to see this also quantified, otherwise, it would be a long article, where in the end you write an extra paragraph saying, but in the end, I don’t care, because comfort is more important. So, for example, the simplicity of the hub gear increases my comfort from 6 to 9, while the resistance only decreases from 9 to 8.5. etc.
From additional tests, belt vs. chain comparison peaks my interest the most. What I find interesting is that in all comparison tests, Pinion is represented only by P1.18 which is their initial product, now already a few years old. How about testing new C1.12 for example? It would be surprising if they didn’t improve the concept based on the gathered feedback. Also, I think interactive calculator with all so far explored comparisons would be the easiest way to combine and absorb all the data.
I’ve been riding a Rohloff for a decade and have had zero issues. I’m even on the same chain. My LBS checked it for wear last week, and said it was fine — the combination of long chain (recumbent) with straight chain line means much less stress.
Longevity is its own form of efficiency.
I guess I’m working towards an overview of resistance, but there are just so many variables. I’m also trying to remain as quantitative as possible with all of these resistance tests, and things like comfort or ease of use are really hard to be definitive with. We’ll see what I can come up with. 🙂
Earlier this week (before I saw this thread) I tried my new Pinion (C1.12) / Gates drive touring bike (14kg) on the 10-mile time trial course that I usually do with an 8kg road bike. The course is a very gentle climb (mostly less than 1%) for 5 miles then return. My road bike time (using aero bars) is currently just under 28 minutes. The Pinion bike (without aero bars) was 30:40, so about 10% slower. This difference, apart from lack of aero position, includes the extra weight, as well the efficiencies of both the gearbox and the belt drive. So a 5% difference due to the gearbox, measured in the article, seem about right to me (past timings suggest that the aero bars alone make a 3% difference).
for hazzle-free commuter use preferably with a belt drive, multigear hubs offer attractive options. they also offer smooth acceleration from a red light.
but they are a nightmare should problems arise out on a long touring ride. would for that reason absolutely never ever fit one of these on a touring bike, and not on an mtb, where stressful gearing under heavy load may be necessary. their weight is an additional problem
so for serious use when travelling they are for me disqualified before you even start.
with sorry to say the exception of the interesting nuvinci, when it comes to resistance figures this solid review shows an acceptable level, but far from ideal. especially the alfine 11 is a disappointment. i would say no to that hub as well. but you should bear in mind that its not much worse than earlier tests of derailer systems utilizing the 11t sprocket, a case where sub-90 percent efficiency is a theme. that sprocket in itself is not a very usable option and surely degrades otherwise fine systems. now even 10t and 9t are offered. ouch.
golden standard for me remains a derailer with 12t as the smallest sprocket.
I would have liked to see a 3 speed Sturmey-Archer in there.
With only one train of gears I suspect it’s almost as good as a single speed.
sa and probably other 5-speed hubs also use one of two differently sized planetary gears at the time. their drag can benefit from using synthetic motor oil as lubrication, but that has to be replenished more often than grease.
only in direct drive do they come close to the low friction of a singlespeed. cranking those epicyclic gears always has a price.
I agree there’s always a price, but subjectively, the S-A 3 speed seems to have a negligible price, which is why I’d like to see it tested. It has only one epicyclic train so there’s not much multiplication of drag.
And it would be nice if they gave us an oil port on the modern ones. 🙂
as only one planetary gear gets used at the time, the price in terms of drag for 3 and 5-speed s-a should be roughly the same, and indeed is according to my subjective experience. i feel in both cases it is acceptable and small, but not negligable. they have been tested in the past, if i remember correctly drag at 100-150 watts is 4-5 percent in direct drive, and 7-8 percent when the internal gears are engaged.
but in other models, like the ones above where epicyclic gears are at times put in series, there is even a drag to crank the drag. ouch.
if you lay the bike over on the side and roll the wheel it is possible to get synthetic oil into the hub via the bearings. clean it first.
The one thing I think Alee missed in this homegrown evaluation is at what point did he determine which ratio of the hubs he was using to be most efficient? Surely changing the sprocket on each one of the hubs would move the readings up or down and give different results than the sprocket used. May not necessarily be better but without taking that evaluation the results may not be conclusive.
While changing the sprocket ratios will undoubtedly show some variation in the drivetrain efficiency, it does add complexity to the testing because different gearbox systems require different drive ratios to achieve comparable gear ranges. The sprockets used for the Shimano/Nuvinci hubs were 42-20t, while the Rohloff had 42-16t due to its wider gear range. The Pinion gearbox has a wider gear range again, so the drive ratio is 32-24t which equates to the same lowest gear as the Rohloff hub.
These are all pretty common sprocket sizes spec’d on stock bikes with these gearboxes, so I therefore think the testing is reasonable enough (although I’d really like to know if a 42-32t drive ratio with the Pinion makes any difference, not that those parts are available).
Here Alee, you can see for yourself how changing the sprockets dramatically changes the efficiency. Granted you operate these ratios at your own risk but unless you are really over stressing your drivetrain I don’t see any reason for on road riding that you can’t safely operate in these ranges. I have run my Alfine 11 set up this way for the past 2 years completely problem free but I am careful of over doing the torque just to be on the safe side. – Please scroll down the page for the results that I achieved.
Just in case facebook is making getting there difficult try this link & scroll down to August 14th. Sorry, I am not very good at all this weird Facebook stuff. – https://www.facebook.com/Internal-Gear-Hubs-296893474108569/
Great study. I didn’t imagine how great the differences could be between two different hubs !
I would have also been interested to learn about the difference of efficiency between a conventional chain and a belt drive on these hubs. Is there a study somewhere on this subject?
There is! Friction Facts worked out that it’s about 1-watt less efficient to use a belt. http://www.bikeradar.com/road/news/article/chain-or-belt-drive-which-is-faster-36074/
Thanks! I will look at it.
The zero maintenance of a belt drive is one reason to fit them on a touring bike not to exclude because they may go wrong i.e. break which I have never ever heard of happening except in car engines but these belts spin at much higher speeds and are subjected to much higher torque figures.
belt drives are not zero maintenance, they wear and need to be renewed at appropriate intervals. in some drier environments they tend to make noice, then need lubrication with for example paraffin.
in my life i have snapped off a belt drive on bike just once, butvwas then glad to have brought a spare. doesnt weigh much, its a good thing to bring along. of course i dont go with chaindriven bikes without some spare locks and and a chainbreaker, but those find use underways more often, in my case every one or two years.
and on cars snapped two camshaft belts in my life. shit that should not happen, but it does regardless.
have also once by accident as the gear cable failed massacred the internals of a three speed hub gear. not a too convenient situation it was.
hub gears are delicate gadgets in my view not optimal for touring. sorry alee, we can just agree to disagree there. you may be in for a change of opinion once the shit hits the fan also for you. it is likely to happen sooner or later.
keep up the good work with your interesting blog!