A support assembly including a support rotatably disposed with respect to a frame, a repetition lever hinge mounted to the support, and a repetition lever supported by the repetition lever hinge and rotatably disposed with respect to the support, wherein the repetition lever has a contact surface and the contact surface contacts a hammer shank roller provided to a hammer shank for rotating a hammer, and the repetition lever hinge is mounted to the support in a mounting direction that crosses with a tangent-line direction of a line tangent to the hammer shank roller at the contact between the hammer shank roller and the contact surface.