The present invention relates to a device for measuring the force present in the drive chain of an electric bicycle that basically comprises a metal plate (1) with an axle area for being attached to one end of the wheel axle (2) to receive the force F1 applied to the bicycle's frame by said wheel axle (2) in the longitudinal axis of the bicycle and a frame area for being to the bicycle frame were said frame area comprises tapped holes (3) to be attached to the bicycle frame, at least a force sensor (4), an adjusting screw (5) to adjust said force sensor (4), an elastic overload protection element (6), such as an helical spring, designated to maintain the sensor (4) within a secure load range for protecting it from overloads, and a system of transmission for receiving the horizontal force component F1′ and transmitting a proportional elastic reaction force to the force sensor (4).