A: We all are worried about all the horror stories we’ve read about front hub motor failures;
let’s take a look at reasons for breaking a fork whether Steel, Alloy or suspension forks:
1- Forcing the axle into the drop out and causing pre stress.
2- Inappropriate order or direction of washers or locking washers.
3- Insufficient bolts torque or not providing a proper nut seat on grooved alloy dropouts.
4- A cracked, defective or old fork
5- Loose or defective headset
The horror is always there if you have an un-inspected front fork and the drop-out fails to hold the axle. No matter if that is a motorized wheel or not. Let’s clarify this first; We have both rear and front so there is no bios.
The amount of torque in the street legal hub motors is not enough to break the fork drop outs. The amount of motor traction forces and stress to the fork is negligible compared to brakes forces and stress. All the horror stories you hear are about the bad installation or ignoring the fact that maintenance on the converted ebike should be more often than the regular bike. (It goes faster and long distances)
We have had a single front fork failure once and the reason was the locking washers had been placed upside down pushing the axle away from the bottom of the drop out and creating a high stress which caused the failure. Hammer hitting the axle inside the fork drop outs can be another typical mistake people do instead of filing the drop out to remove paint to 10mm opening. Yet, we don’t recommend motor installation on Carbon fiber forks no matter rear or front.