Current Projects chat and miscellany

always thought it was to balance out the force of the NDS crank being tightened up against the BB

It would do that whichever side it's on, but actually it's just there to control end float, a task it can also achieve with equal effect regardless of which end it goes on. The usual reason for having it on the NDS is that the DS is then positioned consistently, fixing the chain line.

A wave washer on a shaft with end float does not resist or balance the thrust of anything being pushed onto the shaft, it acts as a self adjusting shim to prevent any end float until the axial force exceeds the spring preload of the wave washer. If it's done right, the axial force never exceeds that preload, although clunky UltraTorques suggest that this is not always the case particularly if the shell width is towards the minimum end of the tolerance range. Critical systems use fixed shims in addition to the wave washer so that the preload is constant regardless of the tolerances on the housing length.