A human-powered vehicle system and a control method are provided that reduce power consumption of a detection device. The human-powered vehicle system includes an electronic controller having at least one processor configured to control a detection device provided at a human-powered vehicle to detect an electromagnetic wave having a frequency that is greater than or equal to 30 GHz and excluding visible light. The at least one processor is configured to control the detection device in at least one of a first mode and a second mode that consumes less power than the first mode.