I don't really know if it is more desireable to have the bar over the tire or not. However, in my experience with a front rack that has the hoop over the tire, the hoop does not present any problems, and may add some rigidity. When removed from the bike for shipping the front rack folds almost flat. After the initial installation, it takes about 5 minutes to remount it after shipping. Also, not all bikes have braze-ons that go through both side of the fork blade, as required with the Tubus Duo front rack..

When we use our car to get to the start of tours we haul up to 4 bikes on the car, two on the roof and 1-2 bikes on a hitch mount in the rear. I haul my bike on the roof which requires removing the front rack to allow securing the fork properly to the rack. Before leaving on a tour with our daughters this summer, I removed the front rack and placed it on the rear rack. I forgot about the front rack and put my bike on the car. It travelled unsecured all the way from Oregon to Creston, British Columbia on the top of my rear rack. I did not realize my mistake until I started looking in the car for my front rack. I thought I'd just forgotten it. My wife noticed it when I took the bike off the car's roof. A lot of B.S. to say that some front racks may need to be removed for packing or to use a fork mounted roof rack; and don't lay it on your rear rack for the ride