Carry out fatigue tests on the frame, including testing the frame cracking, fracture, and shock absorption function. Only after that, we start painting frames and spraying brand logos. For the sample ebike, we will test its function, performance, and appearance, and must obtain an experimental report. The factory will organize mass production when the sample ebike is qualified. During the assembly process, the bicycles will be adjusted and reworked immediately, if there are any problems in braking, shifting, and driving angle.