The speed sensor system signals the motor that the rear wheel is moving. Regularly clean the speed sensor magnet on the rear wheel to prevent dirt and brake pad dust buildup. A dirty speed sensor magnet can cause false speed readings or motor errors.

Which speed sensor does my Turbo bike use?

Road Speed Sensor System

Receiving magnet mounted in chainstay; signal magnet on rear wheel's rotor lock ring.

Mountain Speed Sensor System

Receiving magnet in chainstay-mounted bracket; signal magnet integrated into 6-bolt rotor.