A user motion apparatus has a track and a motion assembly. A mounting assembly movably mounts the motion assembly to the outer track surface. The mounting assembly has a first track member connected to the motion assembly and a captive arm with a first arm portion connected to the motion assembly. The first track member is movably mounted to the outer track surface and includes a coupling section extending through the outer track surface. The captive arm has a second arm portion extending through the outer track surface to an engagement height. The second arm portion is configured to engage the coupling section at the engagement height. The second arm portion maintains engagement with the coupling section at the engagement height as the first track member moves along the track whereby the first track member and second track member cooperate to maintain the motion assembly on the track.