Gearing / RPM / MPH Calculator
The gear ratio and speed/RPM info for the different drive sprocket options available are below.
Remember there are variations in tyre sizes and wear will also affect actual readings so this is a guide only.
You can enter your own sprocket and tyre sizes to check the effect on gearing.
Wheel revolutions per minute
RPM / Primary Drive Ratio * Gear Ratio / Final Drive Ratio
US Tire Circumference (inches)
( Width / 25.4 * Aspect Ratio / 100 + Rim Size / 2 ) * 2 * PI
Speed in MPH
Wheel Revolutions per minute * Tire Circumference * 60 / 63360
1 - The error NaN means Not a Number. Basically an invalid result, re enter the values & recalculate.
2 - The early F650GS manual rounded gearing values to 2 decimal places so the figures look different.
1 - The Husqvarna Terra gear ratio's are the same and the calculator is correct for the ABS model.
2 - The non ABS Terra has an 18" wheel, manually enter the wheel/tyre size and the calculator is correct.