Shouldn't. 200 lb plus folks are climbing those ladders all the time. 60 lbs of well-secured bike shouldn't effect anything--warranty or otherwise. By the way a number of us have that same Swagman. When loaded, It does slightly effect your tongue weight. And, depending on where you go, the bikes can get dirty riding back there. I'd like to find some kind of cover for the bikes that will keep them dry in the rain, and won't damage the paint as it flaps in the wind.