Originally Posted by
edwong3
I think I read somewhere that front mounted hub motors should not exceed 400 watts or so. So yes, I can see how a high torque 750 watt front mounted hub motor could present a safety risk.
A front bicycle fork (non through axel) is really not designed to take any torque. It doesn't take much to spin the motor in the drop out, and then you are at risk of the front wheel falling off or getting jammed up. If the fork is steel, it will bend and probably hold together. If it is aluminum (or CF) it will break and then it gets nasty. A torque arm will add a large margin of safety.