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Q & A: Peddling a bike uphill

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Most recent answer: 11/04/2011
Q:
We're having a debate here about bicycle weight vs. wheel weight vs. human weight. Assuming two cyclists are pedaling up a 7% grade at the same wattage and both weigh 150 pounds what is the weight differential as far as a bike and its components go? The idea is that for every pound of rotation on a wheel it translates to 5 pounds on the actual bike as well as 5 pounds on the person itself. Simply put its a 1:5:5 ration for bike wheel to bike frame to person. Keep in mind this is at a 7% grade. What do you guys think?
- Nicholas Kane (age 23)
Newington
A:
If you neglect the opposing frictional forces, which you really can't, the energy input is Watts times time. The energy gained in going uphill is MgH where M is the total mass, person, plus bike frame plus wheels, g is the acceleration of gravity and H is the difference in elevation.   Big wheels versus little wheels doesn't make any difference, it's the total mass that counts.

LeeH

Right- The mass on the wheels counts extra when you're asking how hard it is to accelerate, not how hard it is to go uphill.  Mike W.

(published on 11/04/2011)

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