I recently purchased an Aotema E-bike kit from Berson EV. When the front axle nuts came loose the fourth time, it pinched the wiring and was advised by their tech rep to purchase another controller and that would probably fix the problem. It did not. I again contacted Bernsov and explained the problem and asked if I could return the controller. I received an E-mail back telling me it was a matter of personal responsibility and that this was not a repeated problem with this hub motor.