What i came up with.. it's not the weight of a bumper-mounted bike rack with two bikes that is the problem...it's the action as the rack bounces down the road with the weight of the bikes on the end what is essentially a lever .. to prevent the leveraged 'jiggling' tha5 can lead to the bumper snapping off, i just run a ratcheting nylon strap from the top of the rack to a point on the frame, underneath the trailer and make it tight .. four trailers / mucho towing over the past ten years, and never even the slightest crack in the welds