Just to add that flat racers rarely if ever carry more than 10 stone. To clarify for johnny37, the aim of the horse trainer is to have as little weight on their horses back as the handicapper will allow, as the less weight the horse carries the faster it can run. No one would put up an overweight jockey (overweight in the sense of over the weight they had be designated to ride in he race). this is why many jockeys have to seat off the last few pounds for a race and not drink any water for a few ours beforehand.