The relationship between power output and body weight is everything in the sport of cycling. This relationship, known as the power-to-weight ratio, is the single best predictor of a cyclist’s race performance capacity. Power produced by the cyclist’s body moves the bike forward. The weight of the cyclist’s body resists forward movement. So the more a cyclist can increase his power output at any given weight and the more he can reduce his body weight without sacrificing power output, the better he can perform on the bike.