Wednesday, 4 November 2009

Rohloff Speedhub 500/14

My Raven Nomad doesn't have 'normal' derailleur gears, it has an internal hub gear system called a Rohloff Speedhub 500/14, designed and manufactured by a German company Rohloff AG.

For the technically minded, the Rohloff Speedhub is a bicycle hub containing an epicyclic gearing  (or planetary gearing) system. It has three planetary gear assemblies. The first two assemblies provide 7 gears between them and a third assembly, serving as a reduction gear, doubles this. Hence, the Rohloff Speedhub has 14 gears. All the gears are evenly spaced with a 13.6% increase between sequential gear ratios. There's some fascinating technical documentation contained within Rohloff's online presentation.

For the un-technically minded, the Rohloff Speedhub is a bicycle hub containing lots and lots of cogs that mesh and whir in perfect harmony performing 'magic'. You too can click on the link above, but you won't understand any of it. (But you can look at the pretty pictures).

Cutaway of Rohloff Speedhub - Picture Rohloff AG

The Rohloff hub has been around since 1996 and the same basic design (give or take a few tweaks) has been in production ever since. I believe that hub units have been given sequential serial numbers and my hub is no. 98806, so maybe close to 100,000 units have been produced so far.

The advantages and disadvantages of a Rohloff Hub v. Derailleur gears has been debated thoroughly over the years and this is definitely a product that polarizes the cycling community. For a cross-section of written views, from nay-sayers and yea-sayers, try the following links: 1 2 3 4 5.

 Cutaway of Rohloff Speedhub - Picture Rohloff AG


Here's my distilled take on it, with respect to long-distance adventure touring. (I suppose I must side with the yea-sayers seeing as I bought a Rohloff equipped bike...).

Advantages (all minor points it has to be said):
  • Ability to change gears while stationary - This is the useful convenience. A loaded touring bike is very heavy. If you stop, or are forced to stop, in a high gear on a derailleur geared bike, to continue you can either slowly crunch and slip your way through the gears to something more manageable or lift the back wheel up and simultaneously turn the crank (and flick the gear changer somehow). Either way is not pretty and will result in some groaning.
  • Less drive chain maintenance - Derailleur gears work very well when they are clean and well lubricated, but over time they clog up with a mixture of dust, mud and oil, become less efficient and eventually need maintenance. This process is greatly accelerated in wet weather and on wet, muddy roads, even more so. Restoring efficiency requires cleaning the chain, the cassette (and the gaps inbetween), the chainrings, the rear derailleur and jockey wheels and the front derailleur followed by a lubrication step. A Rohloff equipped bike only has a chain wrapped around a single sprocket and single chainring. Everything else is sealed from the elements This simpler system is less susceptible to clogging up, so maintenance intervals are increased and when maintenance is required, it is quicker and easier to perform. Less oil on your hands during a tour must be a good thing!
  • Less wear - Chains, sprockets and chainrings wear down on both systems. The chain, sprockets and chainrings of a derailleur geared bike will wear more quickly though, for a number of reasons. When you change gear the chain jumps (derails) over the sprockets causing additional wear to both items. For most gear ratios, the chain is not perfectly in line between the sprocket and chainring. This will result in additional sideways stress on the chain and increased wear. The derailleur system has a greater surface area to collect contaminants and this will also contribute in the wearing of the system. The non-derailling, straight chain-lined, inherently cleaner Rohloff drive system also has a further trick up it's sleeve. It's sprocket and chainring can be reversed and reused when worn down on one side. Only a new chain is required to return the drive chain to an 'as new' condition.
  • Less to damage - I wouldn't call a derailleur system fragile, especially when protected somewhat by a rack and panniers, but there is clearly more 'sticking out' to knock and damage. The rear derailleur and gear hanger is open and vulnerable to damage from impact while riding especially on poor road surfaces (stones, rocks, sticks, crashes) and during transportation (baggage handlers). (The Rohloff EX box is also vulnerable to impact damage, but less so I feel).
  • Easier spoke replacement - When a wheel is fit for purpose and built properly, it shouldn't break any spokes, but inevitablly it will at some inconvenient point. The majority of spoke breakages on a derailleur equipped bike will occur on the cassette side of the rear wheel. This is due to cassette side spokes being tensioned higher than all the other spokes (wheel dishing). The cassette will need to be removed to replace one of these spokes and that will require tools (normally a cassette lock ring tool, a large spanner and a chain-whip). All spokes on a Rohloff hub wheel can be replaced without the need to remove the sprocket and hence no additional tools are needed beyond a spoke key. (OK, this one's only a minor advantage as you could carry a FiberFix spoke for a temporary repair and/or a hypercracker tool, but still...). Also, the rear wheel of a derailleur equipped bike has spokes of two different lengths, whereas those on a Rohloff equipped wheel are all the same length.
Disadvantages:
  • I'm buggered if the Rohloff hub fails - AFAIK nobody has ever reported a complete Rohloff hub failure, but there have been several documented cases of the hub's flanges cracking or failing (1 2 3 4 5) and needing replacement. I've also read of the occasional hub developing partial problems (bearing play, certain gears slipping or unusable) and having to be returned to Rohloff for servicing. So, Rohloff hubs are not bullet-proof. This is the coup de grace as far as the nay-sayers are concerned. They argue that if the Rohloff hub fails in the back of beyond, it will be almost impossible to repair and nobody will have spares locally. This is irrefutable. They continue that local spares for their derailleur system will be easier to obtain. This is also true but ignores the larger picture. The hub gear (or derailleur system for that matter) is not the only or the most likely point of failure. It could be argued that the wheel rims, the handlebars, the forks and even yourself are more susceptible to catastrophic failure (what we're taking about here) and all cyclists are equally susceptible to these failure modes. You may be a considerable distance from any bike shop assistance and in that case again, it doesn't matter what's failed, you are stuck and will be walking (unless you've broken your leg). Overall, there is the very insignificant risk of failure of the hub drive system, but if it does happen, virtually any urban centre is reachable by UPS in a few days, so spares can be shipped out. A Rohloff hub failure it isn't worth fretting about.
  • Requires a very short spoke length - Actually, this one hasn't been mentioned much in discussions about the Rohloff hub, but has caught my attention. The Rohloff hub is big and consequently the hub flanges are very high compared to normal hubs. This means that when building the hub into a wheel, unusually small spoke lengths are required. (Mine are just 238mm long). This would imply that obtaining the correct spokes locally could be an issue. I would always carry a few spares with me for replacing the odd breakage, but if I needed to do a complete rebuild onto a new rim while away on tour, although I could probably reuse most of the existing spokes, I might feel inclined to carry a few more spares to cover this operation. Whilst we're talking about wheel rebuilding, my rear Andra 30 rim has spoke holes that are 'Rohloff drilled'. That is, the spoke holes are drilled at a slight angle to reduce mis-alignment between the nipple and spoke caused by the large hub flanges, even when lacing 2x cross. This mis-alignment has been reported as the cause of some Rohloff hub related spoke breakages. Obviously, a locally sourced rim won't have this attribute and then I may be exposed to a slight increase of future spoke breakage. (It may be possible to 'cold set' the spoke holes of the new rim a little to help with alignment, though).
There are a few other 'disadvantages' that are commonly cited that I feel are in fact non-issues, being either easy adjustments, a minor inconvenience, irrelevant or insignificant. These are:
  • More expensive - Intially yes, but because of reduced drive chain wear when compared to a derailleur system, the cost difference diminishes over time. I think you need to consider the 'whole of life' aspect of this product when thinking about cost, not just the 'headline' purchase figure. Also, the additional cost (if any) is probably insignificant when compared against the total cost of a number of long distance 'adventure tours'.
  • Heavier - It's perhaps an additional 400 grams in 40kg. That's 1%...
  • Hub requires an oil change every 5,000 km - True and this requires the carrying of (or rendezvous with) an 'oil change kit' on 5k+ tours. I feel this is adequately offset by the general reduction in drive chain maintenance highlighted earlier.
  • Whirring / noise especially in gears 1 thru 7 - There is additional noise from the hub in these low gears, but the noise is not a disadvantage and actually, I quite like the noise! It also reduces as the hub runs in, apparently.
  • Increased friction especially in gears 1 thru 7 - Slight, a percentage point again, nothing to worry about. I don't feel any more emasculated climbing hills with a Rohloff v. derailleurs.
  • Changing from the 7th to the 8th gear or vice-versa is problematic - Not really, you'll get used to it. You do need to back off the pressure on the pedals during this gear change (or you'll end up in 14th gear until you do back off), but this is easily learned and becomes second nature. There's probably more chance of fluffing a simultaneous front and rear derailleur shifting manoeuvre to select the next gear ratio. (I do concede there is a slight issue with reading the Rohloff shifter, especially in reduced light, because of it's black-on-black numbering system. This can make it difficult judging when you're in 8th gear and needing to back off for the next downshift. The same applies, obviously, when riding at night).

One further point worth noting is that not all Rohloff equipped bikes are created equal. Some require a chain-tensioner, if they don't have a eccentric bottom bracket or some adjustment available in the rear dropouts to maintain the chain tension. Some use an internal gear change mechanism (as opposed to the simpler and neater external 'EX' box). Some require a long torque arm, if the bike hasn't got Rohloff OEM dropouts. All of these things add complexity and compromise into the Rohloff design and negate some of the advantages of the simplicity of the optimised system. Something to bear in mind.

As a final statement, I would say that either a Rohloff geared bike or a derailleur geared bike would work well on a long tour with very few, if any major problems. So, the decision of using one system over the other is, I suppose, an entirely moot point!

1 comment:

Bryan said...

Hi Shaun, Your upcoming trip is quite similar to my trip which I completed just this last September. I did 8,500+km. I also have a Rohloff, but it was totally hand built locally. It's steel, lugged, Tubus racks, Schmidt dyno, DLumetec LED light, S+S couplings. I actually considered a Thorn but preferred to spend my money locally (in Canada).

A relative of mine posted my daily trip diaries at http://www.nomadaroundtheworld.com/across_canada. Also, I'm currently transcribing my diaries with more photos at www.crazyguyonabike.com (search for "UNIVAC"). I hope to have that completed within a month.

I'll monitor your preparations!

Regards,

bryan
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new westminster, bc, canada