A thrust aid device to permit a bicycle rider to apply increased thrust to the pedals of the bicycle. The thrust aid device comprises an elongated mounting member having one end adapted to be fastened to the seat post of a bicycle and a movable thrust arm connected to the opposite end of the mounting member. The thrust arm is selectively movable between a first storage position and a second raised and operable position wherein the rider can push his or her hips against the thrust arm in the second position while pedaling in order to apply increased thrust to the pedals. One preferred embodiment has a vertically oriented sleeve in which the thrust arm slides between a retracted position and a raised operating position. The rider pushes the thrust arm down to move it to the retracted or storage position. A spring raises the thrust arm to the operating position when a latch is actuated. Another preferred embodiment has a rotary joint where the rider pushes the arm down to disengage a slot and then rotate the arm rearward to a storage position.