Is there a greater concern when roof-racking a bike than the fear of someone walking by your car and lifting your steed as you enjoy some post-ride grub? You can't always park in front of the windows. That's why they make lockable roof racks. However, until now you haven't been able to secure your thru-axle equipped mountain bike. The Rocky Mounts Drive Shaft will do this for you so you can rest easy while you're away from your car.
The Drive Shaft provides security for your bike by physically clamping the thru-axle. The system works because you can lock the Drive Shaft to your standard locking skewer on your bike mount. Then you load your bike onto the rack with the thru-axle installed in the fork. The Drive Shaft then clamps over the axle and locks down. The clamp force can be adjusted so that, once clamped and locked, the thru-axle cannot be unscrewed from the fork. This effectively locks the front end of your bike to the car.
Rocky Mounts designed the Drive Shaft to accept 20mm and 15mm thru-axles. There are plastic shims that act to reduce the inside diameter down for the smaller 15mm axle size. Without the shims, it's sized for 20mm axles. Please Note: due to the design of the clamping head and the need to accept both axle sizes, the Drive Shaft is narrower than either axle standard. When you mount your bike, you'll simply adjust your bike roughly to center and off you go.