Motorcycle Gear Ratio Calculator

Going down 1 tooth on the front sprocket (or up ~3 teeth on the rear) increases acceleration by about 6-7% but reduces top speed. Conversely, going up on the front or down on the rear increases top speed but reduces acceleration. Front sprocket changes are more impactful per tooth.

If you change the overall number of teeth significantly (more than +/- 2 teeth combined), you may need a longer or shorter chain. Adding teeth to the rear requires a longer chain. It is recommended to replace the chain and both sprockets together for even wear.

Measure the distance your motorcycle travels in one wheel revolution, or calculate from the tire size. For example, a 180/55-17 rear tire has a circumference of about 78.5 inches. You can also use: Circumference = pi x (rim diameter + 2 x sidewall height in inches).