Frank Krygowski wrote:

Internally geared hubs exert torque on the
bike frame or dropouts in certain gears.
If the axle has flat surfaces and the
washer's inner hole has matching flats,
I think the washers you describe are a way
the hub transmits that torque to the frame.

Okay...?

The surfaces are flat! But there is also the
hook! Perhaps the hook is just a way of putting
it (the washer) there so the flats align
easily? But somehow that sounds unlikely!

And what happens with the torque if there is an
ordinary washer?

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