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Rollout Calculator and Gear Chart

BMX Ultra has created a really great rollout calculator that tells you exactly what the distance is covered by 1 full crank rotation based on your tire size and gears.

Click here to calculate your rollout

Here is a handy tool for calculating your gear ratio.

The formula to find the gear inches for your bike is simple.
Divide the number of teeth in the front sprocket, or freewheel,
by the number of teeth in the rear sprocket, or freewheel,
and then multiply by the diameter of the rear wheel.

Gear Calculator
Wheel: 20" x 1.75" rim with 20" x 1.75" tires20" x 1.50" rim with 20" x 1.50" tires20" x 1-3/8" rim with 20" 1-3/8" tires20" x 1-1/8" rim with 20" x 1-1/8" tires20" x1.75" rim with 20" x 2.10" tires20" x 1-1/8" rim with 20" x 1-3/8" tires20" sew-up rim with sew-up tires24" x 1.75" rim with 24" x 1.75" tires24" x 1.50" rim with 24" x 1.50" tires24" x 1-3/8" rim with 24" x 1-3/8" tires24" x 1-1/8" rim with 24" x 1-1/8" tires
Chainwheel teeth: 2526272829303132333435363738394041424344454647484950
Freewheel teeth:  910111213141516171819
Gear ratio:
Gear size:

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