You're browser has JavaScript disabled. You will not be able to use the calculator. The basic formula used for calcualting the spring rate is:

Rate = (wireDiameter^4 * 1470000) / (coilDiameter^3 * numberCoils)

This is valid for all steel springs. Not valid of other types.

F650 Spring Rate Calculator FAQ

compiled and edited by Brad #1002
much of the content was provided by cugino pegaso
Please read the Disclaimer before attempting any work in this FAQ.

For FAQs related to forks, shocks, maintenance and aftermarket options:

Spring Rate Calculator

If you have ever wanted to be able to determine what strength spring is on you rear shock or in the front forks you can use this information to help you figure it out. You'll need to be able to measure the spring. That means it is best if it can be removed from the motorcycle. If you don't want to remove the spring you at least need to be able to reach it to measure it. Of course, the springs in the front forks can't be measured without being removed. See Forks Maintenance FAQ for more on how to remove the fork springs.

The three measurements you need from your spring are:

All dimensions in decimal inches. The default values are approximately the same as a stock F650 Classic.

Wire Diameter:
Coil Diameter (center to center):
Number of Free Coils:
pounds per inch.

The formula used to do these calculations is provided in case you are away from your computer and just want to use a calculator. The '^' notation indicates 'to the power of'. This formula applies to steel springs only.

rate = ( wireDia^4 * 1470000 ) / ( coilDia^3 * numCoils )

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