System for controlling the electric motor of a pedal-assisted bicycle comprising said electric motor coupled to a wheel of the bicycle, a pedal-thrust group connected to a wheel of the bicycle, a battery configured to exchange energy with the motor, said control system comprising: - a pedal-thrust cadence sensor configured to detect a pedal-thrust rate exerted by a cyclist on the pedal-thrust group and configured to generate a signal representive of the detected pedal-thrust rate; - a pedal-thrust torque sensor configured to detect a torque applied by the cyclist on the pedal-thrust group and configured to generate a signal representive of the torque applied by the cyclist; - an acceleration or speed sensor of the bicycle, configured to generate a signal representive of the acceleration and speed of the bicycle; - a sensor for detecting the power of the motor and configured to generate a signal representive of the detected power of the motor; - a closed-loop controller of the torque applied by the cyclist on the pedal-thrust group, configured to generate a reference motor command signal based on the cyclist's torque (I° cyc) based on the error between a reference cyclist torque (T° cyc) and the cyclist effective applied torque (T cyc) detected by said pedal-thrust torque sensor; - a closed-loop controller of the resisting torque of the bicycle, configured to generate a reference motor command signal based on the resisting torque (I° env) based on the error between a reference resisting torque (T° env) and an effective resisting torque (T env) determined based on at least said signals representive of the motor power, of the pedal-thrust cadence, and of the bicycle speed or acceleration; - a dividing module configured to generate a motor reference command signal (I° mot) based on said reference motor command signal based on the cyclist's torque (I° cyc), on said reference motor command signal based on the resisting torque (I° env), on said effective resisting torque (T env), and based on a reference dividing parameter (α); - a pedal-thrust cadence sensor configured to detect a pedal-thrust rate exerted by a cyclist on the pedal-thrust group and configured to generate a signal representive of the detected pedal-thrust rate; - a pedal-thrust torque sensor configured to detect a torque applied by the cyclist on the pedal-thrust group and configured to generate a signal representive of the torque applied by the cyclist; - an acceleration or speed sensor of the bicycle, configured to generate a signal representive of the acceleration and speed of the bicycle; - a sensor for detecting the power of the motor and configured to generate a signal representive of the detected power of the motor; - a closed-loop controller of the torque applied by the cyclist on the pedal-thrust group, configured to generate a reference motor command signal based on the cyclist's torque (I° cyc) based on the error between a reference cyclist torque (T° cyc) and the cyclist effective applied torque (T cyc) detected by said pedal-thrust torque sensor; - a closed-loop controller of the resisting torque of the bicycle, configured to generate a reference motor command signal based on the resisting torque (I° env) based on the error between a reference resisting torque (T° env) and an effective resisting torque (T env) determined based on at least said signals representive of the motor power, of the pedal-thrust cadence, and of the bicycle speed or acceleration; - a dividing module configured to generate a motor reference command signal (I° mot) based on said reference motor command signal based on the cyclist's torque (I° cyc), on said reference motor command signal based on the resisting torque (I° env), on said effective resisting torque (T env), and based on a reference dividing parameter (α);