A lighting system for a bicycle. A lamp and a beam are mounted to the bicycle. A generator is mounted to the beam such that the beam holds the generator in position to be frictionally driven by contact with a bicycle wheel. The generator provides a three-phase output voltage. A sensor monitors the generator and provides an output signal proportional to the speed of the bicycle. A first sensing circuit receives the output signal from the sensor and provides a first control signal when the output signal exceeds a first predetermined value. The first control signal is operative to change the output voltage from the three-phase output voltage to a single-phase output voltage to prevent damage to the system.