Ok thanks, thought that might be the case! Yours is a good idea compared to cost of bike rails, thanks

Hi guys
I've just picked up a cheap Thule 973 rack which has no bike support rails. I wanted to put a backup box on it but see from thules instructions they place the box on top of these rails with a fixing plate going into the v of the bike rail. Does anyone know if it would be safe to put the box ...