The sketch shows simplified a crank dynamometer for bicycles. Represents the crank, the spring (spring stiffness c) and the damper (damper constant k), so that together with the mass, m, as a substitute mass vibration system can be used. The crank arm is fixedly connected to the frame, and is loaded on the pedals with an imbalance excitation (Unwüchtmassö u, angular frequency Q). The unbalanced mass u is negligible compared to the mass m.