frame: aluminum alloy With intelligent PAS & Shimano speed gear Motor: 180W high speed motor Wheel size: 20 inch Battery: Nimh, 12V / 8Ah x 2pcs Rated voltage: 24V Loading capacity: 90kg net weight including battery: 23kg top Speed: 24km/h Running distance per full charge: 30 - 40km Charging time: 6 to 8hours This is not common e-bike. How does the system work? a) The rider adds force on the pedal b) the sensor detects the force c) the controller calculates the necessary power d) the controller sends a signal to the motor e) the motor starts to assist the rider by the same force f) Counter step....Motor cut off at once g) Stop step....motor will cut off delaying about one second. CE certified.