In exemplary implementations, tension is applied to a motion transmission element with periodic features by causing that element to mesh with a device that has a pitch slightly greater than the pitch of the motion transmission element. The motion transmission element with periodic features may include, for example: a belt with teeth, or a chain. Further, the motion transmission element may comprise either an open or a closed loop. In exemplary implementations, the width of the teeth of the motion transmission element is greater than the width of the teeth in the rack. This allows room for the teeth of the rack to both fit and move within the gap between the teeth in the motion transmission element. This extra width of the element's teeth is not necessary if the element is sufficiently elastic.