An obstacle detection system determines a probability distribution of existence of an obstacle object corresponding to a distance in an irradiation direction of a transmission wave based on detected strength data per scanning-angle supplied from a radar device. The control unit provides a first signal to command the bicycle device to move in a first manner when the power supply has a first characteristic, and the control unit provides a second signal to command the bicycle device to move in a different second manner when the power supply has a second characteristic. There is a code for the system in which there are \u201cm\u201d number of possible frequencies.