Originally Posted by
Ranko Kohime
I have read a quoted number for Rohloff, but only on Sheldon Brown's site, not Rohloff's. (Though, I would be tempted into believing Sheldon, he seemed to know his stuff) Shimano's spec I have not found, but I'd be interested in reading it if you know where I might find it.
The rest merely post recommended crank-to-cog ratios, which tells nothing, as there is quite a difference between someone my size standing on the pedals, and someone twice my size standing on the pedals.
Both Shimano and Rohloff do exactly the same - provide a suggested "do not exceed" cog/crank ratio. Not a torque value.
I am unaware of documented cases of Shimano voiding warrany if that ratio was exceeded. As a reference, read up a bit on the IGH forum at mtbr.com
On the other hand, repeated downshifts under decent torque almost guarantee to ruin the Alfine (the pawls) - mostly the 11 than the 8-speed, which has been documented on numerous occasions.
I have heard anecdotes of Rohloff refusing warranty work if the recommended ratio was exceeded, but never anything substantiated.