As everyone knows, I’m not a fan of air forks in any guise, but any notion that the KYB PSF air fork on the 2013 Crf and kxf was first to market is just wrong, by my counting it was the 3rd air fork fad that I’ve lived thru, I’m both glad and sad it’s come to an end.
This photo of the very first air fork patent is quite interesting.
First off it’s from UK patent 597,036 and invented by Dowty Equipment Ltd in 1948 and was aimed at fixing some of the major issues of the day including lack of suspension travel, load carrying capacity (more from poorly made steel springs I think) but also rigidity with a “measurable” increase in stiffness to weight ratio reported but possibly just an increase in marketing budgets just like recent times.
These were not only the first “air” fork but the first “registered” upside down fork (usd).
Many will remember of cause that usd forks were invented for pro racers in the states during the 90’s, wait, because their forks flexed, wait, 90’s were before the 40’s weren’t they.
Isn’t marketing wonderful
The air was connected between each leg by an air tube between the fork caps, like those invented, hang on a second, in the late 90’s and then invented again on the KYB’s in 1976. lol.
Damping of cause, in 1948 still left a lot to be desired and was mainly friction but not adjustable as on the earlier girder forks so the friction damping got less with wear, but damping losses were probably offset by lack of maintenance anyway. Final damping, well what could loosely be described as high speed damping but more accurately as last ditch attempt damping, was by bump stop rubbers on both compression and rebound.
Exiting times no doubt which means we must be due for anti dive brakes and Fluro pink riding gear again soon, bring on 2019 - craig
So in the past you have bought expensive suspension components or worked with a number of suspension tuners,re valved, re sprung, and even turned every adjuster you can get your hands on.
For some reason you can not get any faster on your bike.
Do you have problems turning in?
Do you get wheel spin driving out of turns?
Do you get chatter mid-corner?
Does the bike feel like the front wants to wash out on entry?
All of these symptoms are due to improper geometry setup and once a bike is properly set up the bike starts working with you, instead of against you.
The beauty about geometry is it doesn’t care whether you have $10,000 Ohlins or OEM suspension. Whether you’re a novice, brand new to the track, or a seasoned racer going after a championship,
If its wrong its wrong.
Damping and spring rates are important, springs control what happens, damping controls how fast it happens and we need to have both correct so that geometry can be maintained and lap times lowered.
Most race day issues (once spring rates and damping are considered) consist of chassis balance and geometry.
Geometry consists of a number of measurements throughout the bike that tell us how the bike is going to handle. They consist of rake, trail, wheel base, and swing-arm angle.
Rake gives the bike it’s “flickability”, allowing you to changed direction or throw the bike into a corner.
Trail is a measurement along the ground relative to the front axle and rake angle. Trail gives you grip or stability. When a bike wants to wash out or drives wide on entry, it’s due to too much or too little trail. We control rake and trail with fork heights, clamp offsets, and springs ( fork and shock sag ).
Swing-arm angle is measured again, in degrees, and is taken from the swing-arm pivot and the rear axle. This helps to determine your grip driving out of corners and is dependent on shock spring rate, swingarm pivot height, rear axle location and ride height.
Wheelbase plays into all three other measurements to help get your numbers you want to achieve.
One thing to remember is changing tires, gearing, moving axles, and changing fork/shock height will immediately change these numbers.