Thanks for the response. FWIW, I am interested in using these racks and not just asking rhetorical questions etc. I am looking for ways to carry gear without using a roof rack and your racks seem like a clever solution....there is an adjustable tension in our clips we use at the bottom of the rack that allows for adjustability and versatility.
I watched this video a while back:
The question I am trying to learn the answer too is if there some sort of threaded tension device that pulls along the long axis of the rack rail and pulls the two clamping fixtures towards each other, or does this system rely on pressing the assembly together and tightening it before it loosens?
It's not a direct comparison but Yakima, and Thule rack towers have clamps that squeeze down when you turn a thread, so I am wondering if the TrailRax has a feature that allows you to nurse it into a secure position using some sort of threaded adjuster.