I have been lurking in the Touring Forum now for a while. What an impressive group!
My questions relates to the threaded holes on the top rail of the Tubus Cargo rack. What purpose do these threaded, shallow holes serve? The holes I am referring to are on the underside of the top rail about three inches away from the light-mount bracket. Each top rail has one hole, one opposite of the other. My curiousity has the best of me, and I would be interested if any other Tubus Cargo owners / users have noticed or how they have made use of these holes.
I found at least one answer. The Tubus German site offers a spring-loaded clamp as an accessory. The cross-member for the clamp appears to screw into the holes referenced in my original post. Thanks for your comments.