**I wanted to solve this problem mathematically.**I have done calculations which show that it is in principle safe to mount a hub motor in every front fork.

http://www.avdweb.nl/solar-bike/mechani ... motor.html

**The approach is:**

Performing strength calculations on a bicycle's front fork is not possible because hereof no information is provided. But I suppose that a front fork is in principle strong enough for hub motor mounting if the motor forces at the fork are lower than the brake forces, which can handle a front fork easily. Since the fork design is basically symmetrical, whatever it can take in braking force should be more or less the same as the hub motor pulling force.

This is an e-bike with a hub motor mounted in a dedicated carbon front fork:

**Hub motor torque arm length calculation:**

For the distractions see my website.

**The conclusion is:**At 2cm distance to the axis, the torque exposure to the fork from a 20Nm hub motor is equal to the maximum substituted brake torque. For a hub motor of 40Nm the torque arm should be at least 4cm long if we assume that the fork is just strong enough to withstand the maximum brake force.

**If the calculations are not correct please reply!**