# Torque arms



## nicknoxx (May 25, 2008)

Why does a Rohloff have a torque arm when an Alfine doesn't?


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## pursuiter (May 28, 2008)

An internal gear hub's planetary gears orbit the sun gear on the axle. An IGH's axle needs to be held tight so it doesn't rotate. The Rohloff and Bendix hubs use a torque arm, the Shimano, SRAM/Torpedo and Sturmey-Archer hubs use washers that fit into the dropout slots to prevent axle rotation.


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## nicknoxx (May 25, 2008)

Yes, I understand that there is a torque that needs to be restrained, what I don't understand is how the Alfine can 'get away' with just washers when Rohloff don't think this is satisfactory.


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## rockyuphill (Nov 28, 2004)

That's a good indication of the difference in maximum torque the hubs are capable of withstanding. 

If the bike has the Rohloff specific dropout, it can use the OEM 2 axle plate instead of a torque arm, but if you use that same axle plate on a typical light track end it will spread it quite easily.


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## itsdoable (Jan 6, 2004)

Rohloff has an OEM-1 torque arm that works similar to the Shimano/SRAM non-turn washers, only it's bigger and requires a longer dropout. It fits into a track mount perfectly, but has been known to pry apart the steel mount under load (unless it was specifically desiged to take that load). The Rohloff can impart a considerably larger torque to the frame, partly because of the gear range, and location of the direct drive gear (11). I suspect they tested the Shimano/SRAM/Strumy style non-turn washers, and found they were not sufficient for the job.


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