These calculations are pretty straight forward.

I disagree that the power required to overcome rolling resistance varies directly with the speed (I think it should vary with the square of the speed) but I am in the definite minority on this so am probably wrong, It makes little difference because this is such a small component compared to air resistance at any significaant speed.

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Frank,
An original Ironman and the Inventor of PowerCranks

this must have to do with assumptions they make about aerodynamic drag and not something wrong with the formula compared to others.

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Frank,
An original Ironman and the Inventor of PowerCranks

[reply]this must have to do with assumptions they make about aerodynamic drag and not something wrong with the formula compared to others.[/reply]

It looks like aerodynamic drag is done by the cube of the speed. Is that correct?

the quare of the speed. It is the power that is required to overcome aerodynamic drag that varies with the cube of the speed. It is why it is such a big deal to increase ones speed at the higher speeds. it takes about 8 times the power to ride at 30 mph than it does to ride at 15 (not exactly because there are other losses also with different relationships but at high speeds they become small in comparison to wind resistance).

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Frank,
An original Ironman and the Inventor of PowerCranks