Dave-
Thanks a bunch. Very helpful! So how are you supposed to cartop one of these with the floor rack all jiggly, dangling from the two ends? I guess you don't, at least not if you want an unbroken floor rack! Just to be clear, if there are five cross pieces, then one is in the center; your center spread is 10 1/4 inches. Is this including the extended ends of the center cross piece, or just from outside to outside of the runners? Again- thanks very much. I didn't expect such a thoroughly helpful answer!
H.E.