I have an electric bicycle that is powered with a front wheel motor. I have been using the bike regularly for 3 years with no major issues.
Recently, the front forks of the bicycle (it's a giant mountain bike) sheared off (where the wheel connects to the forks). I had wondered if this might happen. A bicycle is designed to be powered via pedals not via the front wheel.
The forks were replaced but the same thing happened a week later.
Has anyone had any similar experiences or can recommend a 'strengthened' set of forks that may prevent this from happening again.
Yes I've had a lot of experience with front forks breaking from being powered by a front hub motor. The best thing I ever did was to buy a Cro-Molly STEEL front fork. If the front forks are not steel then they WILL fail, it's only a matter of time. If you're not sure, take a magnet and see if it sticks strongly to a new set of forks before you buy them. Carbon fibre, alloy, aluminum is all too weak and ALL fail. Steel is your only option. A magnet will only stick to ferrous material like steel, it won't stick to aluminum, carbon fiber or alloy.
Thanks - others have recommened torque arms too, does anyone have experience with them?
A torque arm would be a good idea. It is basically a strut that runs from a point on the motor away from the axle to a point farther up the fork tube. The are common on many two wheelers; my first bicycle had one for its hub brake.
There's some discussion of it here: