Gear Inch RPM speed calculator

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A couple o years back I made what I think to be a very useful well annotated excell based gear inch calculator. The idea was that other gear inch calculators are black boxes and you put in numbers and magically you get gear inches. Many people are confused by this simple calculation and the question "how do I get gear inches" or "how do I calculate speed from RPM" comes up all the time on bikey mailing lists.

They are simple yet daunting calculations. So I made this excel spreadsheet that hopefully allows you to calculate these things AND teach you how to do it at the same time. Dig? So click on over here and try it out.

This helps you calculate gear inches, development from your gear ratio and wheel size, and then helps you calculate your cadence given a certain speed and gear ratio and viceversa.

The fatal flaw is that most people down with Excel enough to use this easily probably can figure out the calcs on their own. It really is simple, but unit analyses is a huge hurdle for most people that don't use math all that often.

Try it, email me if you like it, use it or if you have suggestions.

I have a written description on how the calculations proceed here, but it is a bit rough.


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