Functional principle

The assistance control on Stromer S-Pedelecs is initially based on a Hall sensor in the right dropout. The so-called TMM sensor (Torque Measurement Module) measures the force with which the rider pedals. This force causes a pull on the chain. This pull, the crank torque, is transferred to the sensor plate in the right-hand dropout, where it is converted into a mechanical horizontal movement. This mechanical movement moves a small magnet via a Hall sensor. The voltage value generated in this way signals to the bike electronics (Omni) whether and with what force pedaling is taking place. This voltage value is processed in the Omni together with the presettings for support (speed level, torque sensor) and passed on to the MCU (Motor Control Unit). This in turn supplies the motor with more or less power, which can then be perceived as assistance.

If you are interested in the details of force measurement around the TMM sensor, I recommend this Article by the author 'Georgio' in the Dutch forum speedpedelecreview.com.

> CAD Animation | The TMM4 Gen2 torque sensor | IDbike