Hi Don,
As you have steel forks that are also fitted with a torque arm you don't need to worry, as the load on the headset is significantly greater from heavy braking forces applied to a conventional wheel than the torsional forces generated from a front mounted hubmotor under full power.
Forks that are able to be used with disc brakes would be the best option for a front mounted hubmotor as they are designed to withstand torsional forces at the lower end, whereas non-disc brake forks only had to withstand directional forces from the wheel's axle:
The biggest safety concern with a front mounted hubmotor is that the fork's dropouts are simply not designed to cope with any torsional loads from the axle in either direction when a conventional front wheel is used as the wheel bearings prevent this from happening.
However, with a hubmotor, the high torsional forces produced by the stator have to be transmitted through the axle, which is why torque arms should always be fitted when using a hubmotor to help withstand the bidirectional torsional forces produced by the axle within the dropouts while under power
and during regenerative braking.
Alan
