If you know the rear tire spec, the primary and the final reduction ratios, gear ratios, and the redline rpm of a bike, you can get a pretty good estimate of the maximum speed of the bike in each gear.

Example

Rear Tire: 190/50ZR-17 Primary Reduction Ratio: 1.596 (83/52) Final Reduction Ratio: 2.352 (40/17) Transmission Gear Ratios:         1st: 2.615 (34/13)         2nd: 1.937 (31/16)         3rd: 1.526 (29/19)         4th: 1.285 (27/21)         5th: 1.136 (25/22)         6th: 1.043 (24/23) SUZUKI GSX-R1300 Hayabusa Spec

To the right is the relevant spec for SUZUKI GSX-R1300 Hayabusa.

The format of Hayabusa's tire spec is very typical: 190/50 Z-rated 17-inch radial tire. The first number, 190, is the tire width in mm, the second number, 50, is the aspect ratio of the tire, which is the ratio of height over width multiplied by 100, and the third number, 17, is the diameter of the wheel.

The fractions in parentheses indicate the number of gear teeth difference. The Theoretical Maximum Speed Calculator does not accept fractions. To convert a fraction, simply divide the numerator by the denominator.

If you can't find the redline RPM for the bike you are interested in, use the RPM at which the maximum horsepower is achieved.

You don't need to fill all the Gear Ratio input windows with correct figures. You can fill only the windows for the gears you are interested in and fill the rest with "n/a"s or leave them blank.

When all the relevant numbers are plugged into the appropriate input windows, press the button.

Pressing the button restores Hayabusa's relevant data in the input windows of the calculator.