Assume the cyclists are on identical bikes, and their frontal profile is identical (which is obviously unlikely but it makes life easier) so air resistance is not a factor. Two Cyclists, One Hill… 😉

Will the 100 Kg rider have done exactly twice the work of the 50 Kg rider? Logic suggests that the potential energy of the 100 Kg rider should be double that of the 50 Kg rider. If both riders were running a power meter (be it in the hub, cranks, or pedals) well that show double the work having been done? And what is the appropriate measurement for that? Watt hours?

### Answer

Yes, the 100 Kg cyclist (accounting for bike weight, clothing, helmet, etc) performs twice the work against gravity, IE: raised their gravitational potential energy twice as much (W = mgh). But the heavier cyclist would effectively do more work, having to work against friction and drag. They also expend more energy pedaling as he has heavier legs. Leg weight doesn’t work against gravity, but the mechanics of pedaling does require you to overcome inertia (proportional to mass).

You can measure work (and heat and energy) in many ways. Joule, Newton meters, Watt hours, Coulomb Volts etc. With mechanical work, such as cyclists riding up a hill, Newton meters or Joule(s). But those with power meters talk in watts.