Electrically power assisted bicycle with ambient light controlled headlight

An electrically power assisted bicycle comprising:

• an electric motor that generates an assist force to assist human power of a rider;
• a battery that supplies electric power to the electric motor;
• a headlight;
• and
• an operation panel including a display that displays information, a power button that turns on or off the electrically power assisted bicycle, an optical sensor that outputs a signal in accordance with received light, and a controller configured or programmed to control the headlight to be on or off;
• wherein
• the power button and the optical sensor are located adjacent to each other on or in the operation panel;
• and
• the controller is configured or programmed to start controlling the headlight to be on or off in accordance with the signal output by the optical sensor after the controller counts for a predetermined time period after the controller is activated by the power button being pressed by the rider and the controller is put into a state of accepting operations from an assist force setting button that sets the assist force of the electric motor.