This will be a living document to collect the advantages and disadvantages of internally geared hub and derailleur drivetrains.
Advantages of gear hub drivetrains:
Less maintenance because of a sealed system. Lets divide the whole drivetrain for better understnding into two major parts. The first one is the internal gearing hub itself. The second part is the drivetrain which consists out of a chain, the front chainwheel and the cog which is mounted on the right side of the internal gear hub. The internal gear contains the gears and is well sealed against water and dust. The sealing function is done by a more or less good seeling construction and the hub shell. The second major part, the drivetrain, can optional be capsuled by a chainguard (e.g. Hebie “Chainglider”). This will protect the chain, cog and chainwheel from dirt. This chainguard option is not available for derailleur drivetrains because of the changing chainline while shifting between the different cogs and chainwheels.
Less maintenance efforts and costs than derailleurs (Straight chain line, optional wider and stronger chain and cogs available compared to small 7,8,9 or 10 speed chains). The wider and stonger chains are optimized for force transmission and not for flexing ability which is necessary for derailleur systems. Another big point which has an effect on maintenance and efficiency is the chain path. A chain of a gear hub drivetrain has two flex in to direction forward around the cog and back to the chainwheel. The chain of a derailleur drivetrain has to flex more often because of the two derailleur pully wheels. These little wheels will force the chain to turn in a small radius. This has the effect of additive friction in the chain. The friction in the chain is indirect propotional to the size of the cog. This means a smaller cog will effect a higher chain friction. To reduce maintenance to a minimum there are complete capsuled drivetrains (e.g. Hebie “Chainglider”) available. Result: A wide capsuled straight chain of a internal gear hub drive-train lives 4 to 6 times longer (according time and km) than a thin messy flex chain of a derailleur drive-train
Easy to adjust than derailleurs.
No dirty trousers by using the Hebie “Chainglider” for example. Important for commuting!
Higher reliability. This is a requirement for all bicycle applications!
Less fragile to crashes or when bicycle falls to one side. There is no distant derailleur (except Srams “Clickbox”). On children bicycles and freerider this is a problem!
Easy to use with one shifter. The number of a gears for a internal gear hub complies.
There are no ratio overlaps and ineffective “cross” combinations of chainwheels and cogs on the derailers side. For beginners and inside high traffic areas this is a benefit!
Less and simpler parts: Single chainwheel, single cog, shorter chain, no rear derailleur, no front derailleur, no chain tensioner (When using horizontal dropouts), no slack adjuster, no front shifter, no front bowden cable. What´s not there cannot break! Higher reliability for all applications.
Shifting without pedaling. Important for city rides and trials!
Clean and pure apperance. The derailleur is the PC and the gear hub the MAC drivetrain according to design!
Combinations with coaster brakes are possible. This will reduce the overall bicycle maintenance to a absolute minimum. With the coaster brake no (frozen) bowden cables are necessary (possible!). All year commuting requirement!
No chainsuck! When riding off road or bad roads!
The chain cannot jump from chainwheel and cog because of missing rear derailleur. When riding off road or bad roads!
Shifting under force is possible for Sram i-Motion, Shimano Nexus Inter 8 / Alfine and Rohloff Speedhub. When you ride in a sportive way or uphill this should be the hubs to look for!
Constant gear ratio steps in one shifting row (Rohloff Speedhub, Sram i-Motion 9). This is a benefit for long distance riders (20km +). You´ll find easy the right gear to achieve your preferred cadence.
Low shifting force because of pedaling power system (Shimano Nexus Inter 8 / Alfine and Sram i-Motion). This is interesting for children bicycles and when riding in the rain (with reduced grip on the handlebar).
Stronger and longlasting rear wheels. There is only one cog on a internal gear hub. This has the effect that the spoke flange of the hub can be placed more on the outside. That means the spokes from the left side and the right side (cog side) of the hub can be tensioned more homogenius because of a similar spoke angle. This gives a wheel builder the possibility to increase the spoke tension. A higher spoke tension will result a longer lasting stiff wheel.
Picture of a gear hub drivetrain
Disadvantages of gear hub drivetrains:
A lower overall gear ratio. A derailleur drivetrain comes with 550% overall gear ratio. This means with one turn in the highest gear you´ll cycle a distance which is 5.5 times longer compared to the first gear. A Shimano Inter 8 hub comes with a overall gear ratio of 306%. So for a very mountainous region you should go for a high gear ratio. That means you have gears for climbing and for fast downhill in your backpack. An expensive internal gear alternative is the Rohloff Speedhub with a overall gear ratio of 526%.
Heavier than high end derailleurs. Necessary for sportive cycling!
More expensive than derailleurs. This is also a question of quality. But in general the ratio Price/Gear is a advantage for derailleurs. For bikes which are parked poutside and could be stolen.
More complicated than derailleurs. The internal mechanism may be difficult to understand. But normally it´s not necessary to open a gear hub.
8% efficiency loss against derailleurs (except Rohloff Speedhub). Internal gear hubs have a efficiency of 92% compared to 98% for derailleurs. These numbers are valid for new and perfect trimmed drivetrains! There are three friction loss sources inside a internal gear hub drivetrain:
a) Inside a internal gear hub are planetary gears. The planetary wheels cogs into the sun wheels and the ring gear wheel at the same time. This system results a friction loss of 4%
b) Also the friction bearings of the planetary wheels are a source of friction loss.
c) Finally the friction loss of the chain which is also relevant for the derailleurs.
This is the most important disadvantage for sportive riders. But compared to the power loss because of air resistance of the system rider + bicycle this is not worth mentioning!
Inhomogeneous weight allocation between front and the rear wheel. This can be a point for sportive applications (e.g. MTB, Freeride, Downhill)
Less minute adjustment to gear ratios than derailleurs. The gear steps are defined the overall gear ratio can be adjusted by other cogs and cahinwheels. This is again a point for sportive cyclists.
Difficult wheel removal. With the new i-Motion Sram hubs the differences fade. But it´s still an issue to tight the chain. This is not necessary for derailleurs.
The input momentum into the internal gear hub is limited. This means low overall gear ratios cannot be realized (except Rohloff Speedhub). Important point for uphill cycling.
Picture of a derailleur drivetrain
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November 25, 2007 at 11:37 am
Hi there.
You will also be interested in the NuVinci continuously variable planetary internal hub.
There’s a review of it on Bikehugger @ http://bikehugger.com/2007/07/mondo_nuvinci_review.htm
AL in Christchurch , New Zealand.
http://urbanbicycles.googlepages.com/home
March 3, 2008 at 10:55 am
I’m going to buy a Gazelle Swing 3 speeds in the hub Nexus bike and I am frightened with the possibility of having to unmunt the rear wheel for repairing a tyre puncture.
Do you know where can I find any kind of instructions/video for doing it?
THANKSSSS
May 18, 2008 at 7:52 pm
I’d like to put a Rohloff speedhub on my Merlin titanium racing frame circa 1989. The frame has vertical dropouts and is sized for a 6 speed Shimano 105 cassette circa 1989. Is this at all possible or do I have to get a new frame?
May 18, 2008 at 8:07 pm
Fer,
please check the Shimano webpage. There are general maintenance instructions available.
B. Factor,
dismount the rear wheel of your Merlin and measure the distance between the two dropouts. Now compare this length with the Speedhub dimensions (+/- 3mm should be now problem for a titanium frame.
Gruß,
Marco
July 12, 2008 at 2:41 am
Great article!!
Can I change out my Shimano/Nexus 3 speed twist grip shift for a trigger/thumb shifter?
May 22, 2009 at 10:26 am
Actually I have done this with a Nexus 7 hub and it works fine, not as well as the designed for shifter though and of course the ratchet systems intended for external gear systems don’t work so it is friction adjust only.
July 18, 2008 at 4:49 am
Greetings! I am so glad to have found your Blog! And on WordPress no less, this is a great platform for sure!
OK, So I have a few questions and perhaps more than should be adressed here on your comment portion of your Hubstripping Blog, so if you could shoot me an email I would be most appreciative for your help in choosing a internal geared hub for my new dream bicycle project………of I should say selling my car bicycle project!
I am going to have a frame made for me by Independent Fabrications as they look to be making some really nice frames, and want to go with a Speedhub, yet have some questions about disk braking and dropout configurations, eccentric BB etc.. So please shoot me a line if you have time.
AND thanks for your very informative Blog! You Rock for taking the time and love for cycling!
July 25, 2008 at 12:09 pm
Switching from derailleur to shimano nexus -8 has reduced my average speed on a 14 mile commute by 6%. This indicates an efficiency reduction of over 15%, considerably more than you state above. We are getting definitive efficiency measurements done for greenpower electric car racing & I will try to post results here. Results from that forum suggest that the Nuvinci CVT is significantly less efficient still. Note that the shimano alfine now has roller bearings on its planet gears and their advertising proudly boasts “our most efficient hub yet”. With those bearings & OEM grease replaced by automatic transmission fluid, this hub might get up to rohloff standards for efficiency, which would be a profound improvement!
June 14, 2009 at 1:13 pm
Hi Bob,
A delayed reaction, but: Is automatic transmission fluid likely to conform to the specs and/or be better than, for instance, the ‘blue oil’ specified by Shimano for the Alfine 8-speed hub? Will it provide less friction?
August 4, 2008 at 7:18 am
Jerry – Read this blog for a successful conversion to a bar end style shifter. It is an eight speed hub not a three though. Cheers…
http://www.oldspokeshome.com/blog/?p=119
August 16, 2008 at 2:22 pm
If you test ride a new bike with a gear hub, bear in mind that these take a few hundred miles to “run in”. My Brompton (3-speed Sturmey Archer SRF3 hub) has noticeably loosened up over the first 100 miles, especially in low gear. To start with it was like pedalling through treacle.
Ideally you should strip, clean and relubricate the hub when it has been run in, to get the metal particles out of the lubricant.
August 26, 2008 at 11:30 am
Roger is quite right about “running in”. After a couple of thousand miles on the nexus-8, I’m pulling a higher gear than before in a lot of places on my route to work. Our greenpower car is in its third year of racing and is doing significantly better this year, with no changes other than the gearbox bedding in. Wheel bearings will have got worse if anything and I know of no mechanism which would make the motor become more efficient as it wears!
October 25, 2008 at 9:33 pm
Those interested in Rohloff, and other, Hubs.
There is now a Yahoo group to support gear hub bikes and those who are interested in them. Also supports other non derailleur bikes and owners. I started it and personally have bikes with Rohloff, Sram iMotion9 and two with older Sachs 3 speed hubs.
All, except spammers, are welcome to stop by, check it out, and join if interested.
May 27, 2009 at 8:33 pm
I am interested in joining your internal hub group.
I have recently converted a 1987 12-speed NORCO Monterey to a Shimano inter 8 set-up. See;
http://www.cyclofiend.com/cc/2009/cc647-roybird0509.html
Regards,
Roy
May 28, 2009 at 7:58 pm
Hello Roy,
thanks for your interest. Congratulation! Your bicycle conversion project looks great. I can offer you a contribution account on the hubstripping blog. It would be interesting for many cyclist to know more about your experiences during the project and now riding the bicycle.
Gruß,
Marco
October 25, 2008 at 9:45 pm
To me one major advantage of the Rohloff is the oil bath operation. This provides the ability to do oil changes and flush out the metal particles that are smoothed off during the break-in period.
Much easier than disassembling as far as the manufacturer permits, cleaning out the old grease, and trying to relubricate the mechanism. Also the oil bath should provide more effective lubrication as it is not going to migrate out of the pressure contact areas like grease can.
November 9, 2008 at 11:37 pm
I used a Shimano Nexus 4-speed (SG-4R31) on 27-inch rims for 20+ years. It was on a 25 inch Ross frame, and although it was strictly a commuter bike, after countless potholes, hidden curbs and sundry “things that go bump in the night” I wore out the frame and not the hub! The bike is still serviceable (I fear the front forks are fatiguing and could fail catastrophically at a road hazard) but hub still work great. I perceived no efficiency losses from the hub. Recently, I purchased a new Raleigh 700mm hybrid with a Shimano 21 speed Altus derailleur but did not feel it was as efficient as my old 4R31. Now was I happy with the upper range and found myself 90% in the highest gear, 10% in the mid gears, and have never used the lowest gears in 4-months of riding.
So, I purchased a 7-speed Nexus (SG-7C18) with the intent of replacing the Altus. However, I temporarily mounted the 7C18 to the old frame to test it for efficiency and range. It is excellent! I am now in the process of moving it to the new bike. If anyone know the answers to the following questions, would you mind contacting me?
1) At this time I wish to disable or remove the integral brake on the SG-7C18 hub. Can anyone advise a proceedure?
2) Just out of curiosity, can a multispeed hub be integrated to and used with a derailleur?
Thanks much!
Krez
Silicon Valley, CA
For web crawler evasion my ee-ma1L is:
krezwell[period][Shift-2][period]aim[period]com
[delete the brackets and what's between them with their respective keyboard symbols]
November 9, 2008 at 11:50 pm
I noticed I made a mistakes in the previous message encoding my ee-ma1L that I have corrected at the end of this message
Also, does anyone know the number of gear passes (as effects efficiency) in Nexus 4, 7 and 8-Speed hubs?
Again, thanks -
Krez
Silicon Valley, CA
For web crawler evasion my ee-ma1L is:
krezwell[Shift-2]aim[period]com
[delete the brackets and what's between them with their respective keyboard symbols]
November 18, 2008 at 12:23 am
What do you mean in your internal hub advantages section :”Less fragile to crashes or when bicycle falls to one side. There is no distant derailleur (except Srams “Clickbox”). On children bicycles and freerider this is a problem!” how is it a problem on childrens bikes? i ask because i will be adapting a childrens bike to SA coaster 3 speed 20″ (by removng derailleurs) thanks mark
January 7, 2009 at 11:58 pm
one thing i don’t hear much discussion about is the ease of removal of the various hubs. I once had to remove a nexus 7spd just to change a tube and it was a huge pain. Also, the sram p5 has delicate parts that fall out when you remove the clickbox, which you have to do to remove the wheel. how are the the alfine/nexus redband, or imotion 9 in this regard?
January 19, 2009 at 11:03 pm
Question for ya. I am a 55 year old lady just starting all over after many years of having a leg problem. well anyway i bought this bike it is a coaster type beach bike and really quite nice for someone my age. however I am experiencing problems called peddle power getting up even the simplest incline is impossible for me. I was wondering if I might be able to convert this into its sister bike which is a 3 speed nexus derailleur system (internal) that also allows the usage of the regular coaster type. What all would I need to do in order for this to work for me. I just paid 250.00 for the bike a few weeks ago and I hate to have to buy another new one. Can anyone help me out PLEASE.
Thanks
February 25, 2009 at 11:06 am
What do you think about Schlumpf innovations?
Could help to tackle the issues of overall gear ratios’ low range and of low gears’ lack?
April 11, 2009 at 2:00 pm
The data I’ve seen suggest that a 3-speed hub gear is as good as, if not marginally better than, a derailleur system (the hub gear benefits from perfect chainline and no tight radius jockey wheels).
When you go to more than three speeds there is an efficiency drop-off. Certainly anything that puts the drive through multiple planetary geartrains in series introduces a lot of drag.
Sturmey-Archer used to claim that ball-bearing planet gears reduced drag by 60%, but that was 60% of the drag of the planets alone! Their actual measurements showed on overall hub efficiency increase of between 0% and 1%, so the ball bearing planets were soon dropped. There is more merit to ball (or roller) bearing planets when grease is used for lubrication, or if there are multiple planetary geartrains.
Hub gears have sort-of constant frictional losses, so they become more efficient as the rider’s torque increases.
June 3, 2009 at 9:30 am
I have been using a Rohloff hub for 18 months now. Included in that times was 5 months riding through Europe.
One has to be careful about the claim that hub gears have ‘higher reliability’. Yes, being open to the elements, derailleurs do need regular cleaning and regularly suffer from broken cables, maladjusted gears, dirty drivetrain etc etc.
But I’ve yet to have a derailleur problem that I couldn’t solve by cleaning, adjusting, cable replacement and, every so often, chain/cassette replacement.
At the end of our Europe tour my Rohloff started slipping in all of the lower 7 gears. I was away from home – no access to a workshop. In the end I had to send it off for repair meaning no bike for 2 weeks. That’s never happened on a derailleur.
I have to say though that the Rohloff is a superb piece of engineering.
June 8, 2009 at 3:10 pm
Regards internal hub efficiency in the 1:1 ratio internal gear hubs are more efficient than derailer – they have no moving parts -not even a chain tensioner is required.
The Alfine 8 speed 1:1 is the 5th gear –
In 1st , 6th, 7th, 8th gears is only one planetry gear set engaged.
In 2nd 3rd and 4th gears 2 planetry sets work in series and lowest efficiency probably occurs in these gears.
A belt drive and internal hub arrangement that is a very nice combination if i could get a bike like that.
June 17, 2009 at 6:26 pm
Corratec has made an hybrid with Nexus 8 speed and belt drive. I bought one for my girlfriend and have put on a 250W hub motor in the front. This so-called minimotor from Goldenmotor in China has built-in free-wheeling planetary gear, making a very good commuting e-bike, usually going as fast, or faster, than travelling 13 km by car in rush hour.
June 26, 2009 at 9:21 pm
Thoughts on wheel building with geared hubs
I recently had a little trouble with my back wheel spoke breakage.This was on a road bike wheel (27″) laced cross 3.
Where I had gone wrong was that I had not noticed that the spoke holes in the rim were angled alternately towards that side flange on the hub & had laced it out of step. The result was a too large angle on the nipple end of the spokes & consequent breakages.
I’m a heavy rider (>100kgs) and the roads round here are pretty rough, but I still do not expect regular spoke breakages (like every 15 miles…..)
I’ve now remade the wheel with new spokes. I took it to my local bike shop for them to fix and after a fortnight they had made no progress because the spokes were an unusual length & they said they couldn’t get ‘em. My patience at an end & with no prospect of progress I took the parts away from the shop, ordered the spokes from SJS on the web and THE NEXT DAY built the wheel myself in about 2hours.
The point I wanted to make was that because the flange diameter on a geared hub can be quite large, you end up putting a sharp bend on the spoke by the nipple – just where there’s a stress raiser thanks to the end of the thread.
To reduce this angle in future I would lace the wheel cross 2 rather than cross 3, maybe even cross 1 on a small diameter wheel.
This must be a real issue with something like the enormous nuvinci hub.
The “torque stiffness” of the wheel is a function of the angle of the spoke to the rim, and this would be the same with a hub gear laced cross 2 as a smaller hub flange laced cross 3.
Anybody else got any experience in this area?
By the way – wheel building I found a very pleasant & rewarding way to spend a summer evening. I’ll certainly never again give somebody else my hard earned cash to do that job!
September 6, 2009 at 8:28 am
I laced most of my new wheels and the latest one was a SG-8R20 laced to a Mavic X317 DH rim. The spokes were mail ordered. It was done with 3 cross and I did note the more acute angle at the nipple end.
Unfortunately this used hub bought off eBay was defective.
September 11, 2009 at 11:29 pm
This week I had a spoke snap on the back wheel again so I remade it with a 1 cross pattern. 30 miles today, good as gold! there are 2 significant advantages going 1 cross:
1) spoke angle is now same as a normal hub, so no nasty bend on the spokes at the end of the thread….
2) spokes for 1 cross are 262mm rather than 284mm for 3 cross. This size is readily available CHEAP (for 26″ wheels) from chainreaction – arrived the next day.
I’m hopeful this will solve my spoke snapping issues….
October 9, 2009 at 11:03 pm
Great article. Get your articles proof read for mistakes before publishing !
Thanks.