The basics of an electric bike motor is that it converts electrical energy into mechanical energy. Easier said, the electric motor transfers that electric energy into mechanical energy. This mechanical energy is seen by the spinning of the wheel on a hub drive, or the spinning of the chain ring on a mid drive.
To manage the power output of electric bike motors, there are two main sensors used with the controller. A cadence sensor (or speed sensor) and a torque sensor.
A cadence sensor registers the RPM or speed of the wheel to apply the electric assist relative to the Pedal Assist mode that is selected, e.g. 1-5 or Eco, Tour, Sport, Turbo.
A torque sensor manages the Pedal Assist output of the motor by registering the amount of torque being applied through the pedals.
These two types of sensors are used differently in both hub and mid drive motors. Hub drive motors typically use cadence sensors, while mid drive motors use torque sensors. The difference in these sensors is noticeable between both motor types, which weighs into deciding which eBike motor is best for you.