The last step to completing the Bafang conversion kit was mounting the speed and shift sensors and wiring everything together. The speed sensor is basically the same as any other wired bicycle speedometer. A magnet is mounted on a rear spoke and the sensor is mounted on the frame. The control panel is then programmed for the proper wheel size to calculate the speed each time the magnet passes the sensor.
While I was tempted to bypass the shift sensor to save a few dollars, I’m glad I didn’t. Since you must be pedaling to shift the gears and the motor is engaged when the pedals are turning, the motor would be engaged while shifting. The problem is that the motor provides far more torque than the derailleur, cassette and chain can handle while shifting and would damage these parts without the sensor. The shift sensor disengages the motor when you shift for normal torque on the parts when shifting.
Wiring it all together was much simpler than I expected. The Bafang wiring harness and components are all color coded for plug and play wiring. It is just matter of matching the colored plugs, lining up the pins and sticking them together. It was as simple as that and I was ready to ride!