Provided herein is a power assisted motorized vehicle which can be operated in either a manual mode or a motorized mode or in a combination of manual and motorized modes. The vehicle includes, inter alia, a frame connected to at least one fork capable of supporting a wheel having a first driven sprocket assembly and a second driven sprocket assembly, a rechargeable electrical power supply attached to the frame, a motor controller attached to the frame, an electric motor supported by the frame and attached to a first driving sprocket which is coupled to the first driven sprocket assembly and a manual pedal assembly supported by the frame and comprising a pedal crank shaft with two pedals and a second driving sprocket which is coupled to the second driven sprocket assembly.