## How is motorcycle speed calculated?

Max speed (MS). MS = MaxRWrpm * C = 876.225rpm * 78.5 inches = 68783.66 inches per minute. One mile = 5,280 feet = 63360 inches. MS = 65.13 mph which is a reasonable result.

How do you calculate speed with RPM and gear ratio?

Engine RPM divided by total gear ratio, multiplied by the tire diameter and converted for units of measurement, gives vehicle’s speed of travel.

How do you calculate the final drive ratio on a motorcycle?

To determine the final drive ratio, divide the rear sprocket size, say 49 teeth, by the front or countershaft sprocket size, say 13 teeth (like a new Yamaha YZ250F). In this case, the Final Drive Ratio is 3.77 – the front sprocket revolves 3.77 times to make one complete revolution of the rear sprocket.

### How to calculate the gear on a speedometer?

Speedometer Gear Calculator. To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures.