Lose weight (mass) or train? -- effect of losing weight (mass) on power I'm having troubles wrapping my head around this one (I've provided the example from my class notes below): My question -- how does a decrease in the mass of the rider increase his power producing ability by 18 W? Intuitively, I would think that a rider with lower mass will experience less resistive forces when riding (i.e., gravity when on an incline, kinetic friction) and so can sustain the same velocity as a heavier rider without applying as much force and, therefore, less power. From a physics standpoint, how does a mass decrease result in an increase in Power as this example suggests (taken from my class notes)? Thanks!