Motorcycle Air Fork Balance Springs

Although lightweight modern air forks use pneumatic pressure as the main "spring" - they still use these old fashioned steel spiral tubes as "balance" springs. Just using air alone, the "spring rate" you get is very progressive. Imagine your fork is halfway through the stroke. There is half the gas volume, and therefore double the pressure. At three quarters travel, it doubles again. Near the end of the stroke, you've got really firm resistance - good to stop bottoming out. But at the other end - a rider sits on the seat & the initial rate is so soft the suspension looses most of its travel! To make the response more linear & predictable, Kayaba gave the PSF a light wire compression spring to firm up the starting force.

Tuning balance springs for performance is just like the old oils & coils - see our spring selection article info - stiffer rates & higher PSI for heavier riders, softer rates & lower PSI for lighter riders.

These coil springs are sold individually instead of the usual main pair found in oil damped forks - and they have a secondary function inside a KYB pneumatic spring fork too - acting as the rebound stroke top out bumper. For fitting and setting up your PSF1 or PSF2 reb topout springs you should check out our KYB specific tools, and to make sure you can tune your bike in the pits, see our Air Fork Hand Pumps, Gauges & Adaptors.

But what if you're sick of the constant pump-up & air leaks out of short lived seals? What if weight doesn't matter and you want something predictable & reliable? Air forks just don't suit some people. If you want that fancy new engine & chassis, but with comfy old proven damping, we have air to spring fork conversion kits.