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I have an exercise bike with a computer and it looks like 100 revolutions of the pedals is 430 meters, this seems like a lot.

I was wondering if there is a good number for converting pedal revolutions to meters.

I figured that without gearing the average bike wheel is 26" (0.66 M) and so the circumference of the wheel is

0.66 * PI = 2.07 M

In this instance one rev is basically 2 meters. The bike's computer seems to think one rev is 4.3 meters.

I really don't know where they get these numbers from and I am trying to make more accurate measurement of my exercise but the computer on the bike shows made up distance figures, calories etc...

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Even on an un-geared bicycle, I think you would find that one revolution of the pedals isn't the same as one revolution of the tire. That could only be true if the gear on the pedals were exactly the same size as the gear on the wheel, which in my experience the gear on the wheel is always significantly smaller than the gear on the pedals, especially on an "un-geared" bike. – Nathan Wheeler♦ Jul 2 '12 at 15:47

1 Answer

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It depends on what the force is that you are applying to the pedals, and the resistance that the bike is giving you. For a regular bicycle, it's a function of what gear you are in and the tire size. 4.3 meters per pedal revolution isn't in the realm of silly.

The best thing that you want to find on an exercise ergometer is one that measures in watts. Because of various inefficiencies in the human system, watts can be pretty much converted straight over to calories. To find out calories, take your average watts, multiply by time in seconds, then divide by 1000.

So, if you average 150 watts for 1 hour, you would get (150*3600) / 1000, or ~ 540 calories.

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