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Percentage chain wear for ROHLOFF

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Andre Jute:
A chain is the cheapest part of your transmission setup. The more worn the chain, the faster it is likely to wear your expensive chainring and sprocket. This leads to the standard advice, applicable to derailleur bikes, to change the chain before it reaches 0.75% elongation to protect the sprocket and chainring from excessive wear.

However, on a Rohloff-equipped bike (all those without derailleur-type chain tensioning devices, which are the majority) there is the complicating factor that the manufacturer advises that the chain be run slack.

So, in theory, you can run the chain on a Rohloff transmission without reference to the wear, until it lies down and dies, adjusting it when it become grotesquely worn by the eccentric bottom bracket on the Thorn and by sliding slots for the axle carrier on bikes with the factory-designed frame ends; you tell whether the chain is grotesquely worn by it skipping and/or falling off the sprocket or chainring. If you do this, don't be surprised if your sprocket and chainring wear faster than normal. However "faster than normal" is a relative matter as the Rohloff sprocket is very long-lasting indeed, and it is easy to get a long-lasting reversible chainring like the Thorn ali ring or the Surly stainless ring.

You can run a sprocket and chainring until their teeth are hollowed out on one side, then turn them so the straight side of the teeth are presented to the chain, and run them until only little nubby teeth remain. Photographs have been published on the net of amazingly worn gear sets which still worked.

As I say, you can do it, but whether you should do it is a matter of personal choice.

Instead, I proceed from my opening statement, that chains are cheap in relation to all other components, and that my personal choice is for zero service. I run KMC X8-93 chains on the factory lube inside a Hebie Chainglider chain case and never service the chain. Read that again: I add no lubrication to the chain during its entire life. But my chains now last at least twice as long as less competent chains (Shimano Nexus), lubed with white wax, lasted inside Dutch chain cases on my Shimano hub gear box bikes.

The way it has worked out on my Rohloff bike, I've been running the chains up to about 0.5% elongation, which may sound wasteful, but the upshot is that after 10,000km/6000m there is no visible wear on the sprocket. The chainrings were changed for aesthetic and component-matching reasons, and I routinely fitted a new chain each time I fitted a new chainring, but none of the three chainrings on the bike in that time show any wear at all.

At a guesstimate, the chains I took off could easily have been run up, in my system of hub gearbox/fully enclosed chain/factory lube without anything ever added/steel or stainless chainring, to 1% wear without operating trouble, though, possibly, with accelerated wear in the latter part between 0.75% and 1% wear. That would depend on the beneficial effect of Rohloff's unusually slack chain and absence of jockey wheels, about which we do not know enough to pontificate.

If you're running your chain open, I'd suggest that the maximum wear should be the traditional 0.75%, and that you may wish to consider the longterm cost-saving of changing chains at a lower elongation of say 0.5%, or, even better, getting a Hebie Chainglider and running the chain on the factory lube for its entire life, to achieve over time not only a cost saving but a major time saving in chain cleaning. If you want to know more, there's a couple of articles on chain cases on the forum, and a lot of reported experience with the Hebie Chainglider, and articles on the savings available in running the chain inside a Chainglider on the factory lube.

****
I'm not sacrificing a favorite sprocket and chainring combo, which at the cost of an extra chain or two removed a bit early will see me out, to discover whether in the overall scheme of things, looking at the three components of the primary transmission sequence (chainring, chain, sprocket), I could have saved 0.3 pennies per mile. Someone else can take one for the team. If there are no volunteers, Dan will appoint someone to volunteer.  :D

Andre Jute

martinf:

--- Quote from: Andre Jute on September 24, 2018, 01:11:55 am ---A chain is the cheapest part of your transmission setup.

--- End quote ---

True for derailleur bikes and Rohloff, although the new-style Rohloff splined sprockets are cheaper and more convenient than the old screw-on ones.

Not true with the Shimano and Sturmey-Archer hubs I use on several family bikes - these all take a 3 splined sprocket common to most Shimano, old SRAM and Sturmey-Archer hubs, cost currently £2.99 from SJSC in the 22T size I use most. The flat version can be flipped for even greater economy:

https://www.sjscycles.co.uk/sprockets/sturmey-archer-22t-sprocket-332-flat-hsl951/

For a cheap to run, low maintenance commuter or utility bike, my current recommended transmission is:

- Surly 38T chainring (not cheap to buy, but lasts a long time and works well with a Chainglider)
- Nexus 8 Premium hub, currently £69.99 from SJSC without the shifter and fitting parts.
- Sturmey-Archer flat 22T sprocket.
- Basic 3/32" 7 or 8 speed chain (SRAM is the brand generally available locally).
- Chainglider.

Though not as rugged as a Rohloff, I have found the Nexus 8 Premium hubs reliable and adequate for local use in moderately hilly terrain. The SJSC price was low enough for me to buy an extra hub to keep as a source of spare parts for the 4 hubs currently in service on family bikes.

Fitting a Chainglider significantly reduces transmission wear and time spent on maintenance. 

mickeg:
I have mentioned a few times before that I run both a sprocket and chainring with an even number of teeth on my Rohloff bike.

Sheldon said that if you always put your chain on the sprocket and chainring the same way that you could extend your component lifespan.  I am doing that, I cut a notch in one chainring tooth and one sprocket tooth, I always put a link with the outer plates on those notched sprockets.
https://www.sheldonbrown.com/chain-life.html

I would brag about lifespan, but I ride several different bikes and my Rohloff bike has not seen much use this year or last.  And I often use worn chains in winter when there are de-icing chemicals applied to the road, those chemicals rust out a chain very fast.

gearoidmuar:
I use a Rohloff chain tool to measure. When it says change, I do. I get 3 chains into one side of the sprocket and then three into the other.

Matt2matt2002:
Gearoidmaur, out of interest how are you deciding that the sprockets need replacing?

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