I've decided to get a bike rack and am deciding between the Fiamma carrybike and the VW one. The Fiamma has the advantage that it is only a 2 bike rack and therefore a bit smaller It will carry 1 emtb (and sometimes a small child's bike) but I can't see how it or the factory one actually attach to the van. Is one more secure than the other? I'll chain the bikes to the rack but that won't be much help if it's a piece of cake to pull the rack off the van. Also wondering if it's OK to run a hefty chain round the bike frame and through the rear towing eye?