I've got a rack a bit like that, but without the suction cups. Mount on the car with the lower straps tightened enough to keep the carrier in place(as you describe)then with the bikes on, the overhung load fron the bikes pulls the top straps tight - I just tension the bottom straps (pull through the gripping mechanism) a bit more and then the setup becomes a lot stiffer.
Every time I set off I imagine the whole lot will be all over the road within a hundred metres, but it has (so far) always remained in place.
I've got a rack a bit like that, but without the suction cups. Mount on the car with the lower straps tightened enough to keep the carrier in place(as you describe)then with the bikes on, the overhung load fron the bikes pulls the top straps tight - I just tension the bottom straps (pull through the gripping mechanism) a bit more and then the setup becomes a lot stiffer.
I retension the lot with the bikes on, then do a half-hitch on each, then check them all again after the first few miles ("check your Warwick strainers..."😉
