Abstract: A rear sprocket comprises a sprocket body, a plurality of sprocket teeth, a plurality of spline teeth, a maximum spline distance, and a radial tooth-bottom distance. Each of the plurality of spline teeth has a spline crest. The maximum spline distance is defined from the rotational center axis to the spline crest. The radial tooth-bottom distance is defined from a rotational center axis to one of plurality of tooth bottom center points. The maximum spline distance is larger than the radial tooth-bottom distance. The spline crest of each of the plurality of spline teeth is positioned radially inwardly from the tooth outline of each of the plurality of sprocket teeth in the radial direction.

Abstract: An alighting assistance device D of the present disclosure may be a device moving a driver seat rearward in a case where a determination may be made that an occupant seated on the driver seat of a vehicle alights. The device may include a height changer which changes a height of a steering wheel, a sitting height acquirer which acquires a sitting height of the occupant, and a steering wheel controller 33 as one example of a height controller which controls the height changer such that the height of the steering wheel becomes lower as the sitting height acquired by the sitting height acquirer may be higher in the case where a determination is made that the occupant alights.