Gear Inch Calculator Chart
What’s a “gear inch”? Yeah…well back in the High-Wheeler years before 1866 or so, the pedaling gear you had was determined by the diameter of the wheel, because the crank was attached to it, so one revolution of one meant one of the other, too. In that case, Wilt Chamberlain would win all the flat-road races, because his shorter competitors would be twirling too fast on a smaller wheel.
When chain-drive bikes came about with their cogs attached to the rear wheel, the English “gear-inch” concept came about, which allowed a rider to pick front and rear sprockets and be able to compare the distance-traveled per revolution to that of the high-wheelers.
On this chart, the numbers derived by dividing the rear cog into the chainring, then timesing that by the wheel diameter, is the equivalent wheel diameter of your great-great-grandfather’s high-wheeler. That is combo bike history and trivia, but is relevant if you wanna know which is lower, a 34frong x 36rear, or a 24front x 32 rear. The lower the gear-inch number, the easier the gear. Gear charts like this tend to bring out the inner weirdo extreme bike geek in all of us. Beware.