Motorcycle final drive ratios are changed by many motorcycle riders for many different reasons. A few of the reasons riders may alter their gearing are to increase top speed on a straightaway, get increased acceleration from a corner or from a start or to increase the efficiency of the motorcycle by increasing miles per gallon. Most riders know that changing the front sprocket tooth count will produce a large change and, conversely, changing the tooth count on the rear sprocket will have a smaller effect change on final drive. What many riders do not know is how to calculate final drive ratio and determine the effect that a change will have.
The equation for final drive ratio is:
(Rear tooth count) / (front tooth count) = drive ratio