Device for measuring engine torque in a cycle

The device has a deformation and/or strain sensor that is integrated into a ratchet (30) of a free wheel mechanism (28). A drive torque and/or driving power determination circuit is connected to the sensor. The sensor includes a microelectromechanical microsystem that is integrated into the ratchet. A sensor is arranged for determining angular velocity of a hub (10). Another drive torque determination circuit is provided in a separate manner from the former drive torque determination circuit. Independent claims are also included for the following: (1) a cycle hub (2) a bicycle (3) a system for controlling a pedal-assist motor in a pedal vehicle.