The rear "bumper" (4 inch square tubing) will NOT support much weight or torsion type twisting. I destroyed mine within 500 miles. Dodge Guy is right, stop any movement. I took a platform carrier and put it in backwards, carried extra jack pads in it then put the bicycle carrier into the remaining opening. Spacers were just 1-1/2 inch angle iron and it fit perfectly. Moral of the story, don't plan on carrying your bicycle on the manufactures back bumper!