Scoot, it's more complicated as tyres size, cranks length and wheel size play a factor, the chart you use is rather simplified, I use Sheldon's, add your crank length, wheel and tyres size and it give you a better calculation;
http://www.sheldonbrown.com/gears/
@edscoble started
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Scoot, it's more complicated as tyres size, cranks length and wheel size play a factor, the chart you use is rather simplified, I use Sheldon's, add your crank length, wheel and tyres size and it give you a better calculation;
http://www.sheldonbrown.com/gears/