Originally Posted by JCL

I haven't used the BMW version, but I have used a Thule version of the same style. I got rid of it because it was an earlier version, and didn't accomodate a wide enough range of frame tube diameters. Thule fixed that by moving to what they called a 599 Big Jaw version (first picture), and now they have three similar styles for roof mounted, wheels on, support arm, bike racks. If you know that you will always be carrying the same frame style of bike, any one of the styles can work. Bikes have gone to bigger frame tubes, different frame designs, etc, over the past few years and so the safest purchase is one that only contacts a wheel. Three Thule racks are shown below. The BMW rack (not sure who makes it for them, but possibly Yakima) uses a frame clamp with a side arm, similar in concept to the 598 Criterium (second picture).

I would look at Yakima or Thule before the BMW product, myself. I would also lean towards the design that contacts only the wheel (third picture). I use wheel-off roof carriers now, because I have road bikes where I don't want clamps contacting the lightweight frame tubes, but for mountain bikes but any of these styles works well.