I broke a rear spoke and was riding home trying to baby the back wheel, especially on bumps. One of the things I did was stand up on the bumps, with the reasoning that taking weight off the seat would allow the back of the bike to bounce up more freely, thus reducing stress on the wheel. But then I began to think about the issue more. Me standing on the pedals does not reduce the amount of weight on the wheels, so does that really help with the load and shock of hitting a bump?