A method is performed for controlling a human-powered vehicle. The method includes calculating a first movement amount of the human-powered vehicle on a road from at least one of a rotational speed of a wheel of the human-powered vehicle and a rotational amount of the wheel. The method further includes calculating a second movement distance in an advancing direction of the human-powered vehicle and a horizontal direction from the first movement distance and a pitch angle of the human-powered vehicle and calculating a third movement distance related to movement in the advancing direction of the human-powered vehicle and a vertical direction from the first movement distance and the pitch angle. The method further includes predicting a terrain of the road from the second movement distance and the third movement distance.