A control system includes a bicycle includes a crank, a motor and a battery which provides power to the motor. An acceleration detector is connected to the bicycle and detects the riding acceleration of the bicycle. A torque detector is connected to the bicycle and consistently detects treading of the crank and generates multiple instant treading torque values. A controller is connected to the bicycle and electrically connected to the motor, the battery, the acceleration detector and the torque detector, and receives the riding acceleration, the treading acceleration and the instant treading torque values so as to control output of the motor and the battery instantly.