While working at an RV supply store , I had the luxury of trying different bike racks. The first one I tried was the ladder mount. I didn't care for it as the bikes got beat up from banging together, plus it blocked the tail/stoplight. You also had to almost hold the bike over your head to hang it up. Next was the type that fastens to the 4 inch square bumper and has two arms that stick out to hang the bikes on. On a trip on a rough road, one of the arms bent down and I wound up dragging the wheel of one of the bikes. Also womens bikes require an adapter as the bikes are hung from the cross bar. The last one I tried is the best one. It again fastens to the 4 inch square bumper, is made out of square tubing, and has a place where the tires fit down into a slot, similar to the bicycle racks found at some schools. This is the best arrangement by far. It spaces the bikes apart so they don't bang together, and once the bikes are removed, provides a handy place to put a grill, etc. Be aware that if you have a rear storage compartment, that in most cases the bikes have to be removed to open the compartment.
2002 Jayco Eagle 300FSS Travel Trailer, 2005 Chevy 2500HD Crew Cab 4X4 w/Duramax, RDS 60 Gallon Toolbx/Tank Combo, Edge EZ, Boost Stick, Bilstein Shocks, Michelin 265 MS2, Isspro Pyrometer and Boost Gauges, ARE Topper, Honda EU3000