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Constant increase in pressure with normal air was 3-6psi in upper chamber, and 11-13 in lower chamber. This is during first session.
With Nitrogen it was 1-3, and 7-9 maybe in lower chamber.
So the extra above 76% for sure makes a difference.
Started out my days of testing (have about 30 days/hours of testing on them) with for example 160psi upper chamber, 175psi lower chamber. After 10min pressure was up to ~164psi in upper ("ok" increase" but for sure noticeable), and ~188psi lower chamber (un-rideable).
Much better with nitro (almost cut the increases in half), but lower chamber still to bad to actually work for someone that does not have nitro-tubes and mechanic and excel sheets to manage air pressures for various times of day and temps.
Talked to WP USA and Europe about it, their solution was to bring a stand to the pitlane and reset it after first 10-15min of riding. I got it exchanged to spring based CV fork...
PV^gamma = constant
https://en.m.wikipedia.org/wiki/Polytropic_process
For application to suspension See page 13 or Eq. 3 on Page 14 of
https://digital.library.unt.edu/ark:/67531/metadc56410/m2/1/high_res_d/…
Happy studying,
An Aerospace Engineer
The Shop
10/23/17 merry mole day
Nitrogen doesn’t have special anti-moisture properties. It’s free of moisture because of (a) the way it’s made, and (b) it’s packaged for sale to make sure it has no moisture.
Who gets their air from a source that’s been handled the same way? Almost nobody. At best the compressed air system at Joe’s Garage on the way to the track might have an old busted arse water trap that gets drained every few days. At worst I might hook up my on board compressor in my 4x4 with absolutely no drying on it at all.
On those hot days in summer when the humidity is reaching 90% or more the air has just about as much moisture is it can physically hold. Think about what might happen when you roll the bike out of the garage in the morning, check the tyre pressures and add some air. That warm humid air hitting the cold surface inside the tube is not dissimilar to pulling a cold can of Coke from the fridge and letting it sit on the table for a few minutes.
Sincerely
Yamaha owner.
Factory Star racing guys on the 250's use air forks. Here is the link. https://www.youtube.com/watch?v=w4bF4a6bmRM&t=155s
Just like the old Olympia beer ad, "it's the water..." Nitrogen is the cheapest dry gas that will work for this application.
And nitrogen
I have 2023 xcf350 and also did the glide kit and from another thread I did try the motor oil for more lubricity, I am very happy with air forks this is the second bike I've had, once you dial them in they work great.
Sincerely,
A jackass engineer - jack of all trades master of none
My buddy runs helium due to its monatomic properties…says it helps him clear the finish line double,
Well, closer to 78% actually...
And given a 'Nitrogen' filled tyre will actually be about 93% Nitrogen, the difference is negligible.
I put helium in my tires and air forks. Makes them lighter and I can jump farther.
Not sure about air forks but for tires, using nitrogen is marketing, or at best it's a way to get dry gas, that's all.
Indeed moisture makes all the difference, that's why MotoGP factory teams use tyres with two air valves so they can flush dry air between every session to make sure they use air as dry as possible. They use 22 tires per weekend, typically kept around 90 °C in tire warmers, they go over 100 °C for the front and 120 °C for the rear. They do have the budget for nitrogen, if it could give them the tiniest improvement in performance they would absolutely use it.
https://x.com/PeterBom4/status/1643218642044178432?s=20
Pit Row
Have you ever tried air in a shock instead of nitrogen?
Post a reply to: Has anyone tried nitrogen in air forks?