Abstract: There is provided an apparatus and method for measuring and monitoring the torque exerted by a cyclist during pedaling of a human-powered vehicle, as for example a bicycle, including an electromagnetic emitter which is adapted to be fixed securely to a rear wheel hub, for generating and directing a beam of electromagnetic radiation towards a rim of the wheel, and a detector mounted on the wheel for detecting the movement of the beam when torque is applied to the wheel, the movement being indicative of an angular displacement of the hub with respect to the rim and directly proportional to the torque. Either alone or using optical elements, the beam is directed to travel at least a distance between the emitter and the rim before detection. The measurement can be used to provide a power output.