When I posed the question I should have clarified a bit. I don't mean a fatter rider vs a rider with low body fat. I really meant two riders of equal skill, experience and body fat %… etc. I don't think there's any debate that a fatter rider's performance will suffer from most physical contests versus his leaner counterpart. Certainly a 300 lb. lineman with 10% body fat is probably, again all things being equal, a better player than a 300 lb. lineman with 20% BF.