Mountain Bike Reviews Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
233 Posts
Discussion Starter · #1 ·
Anyone know what pressure this should be at? I did some DuckDuckGo'ing and didn't really find anything. I found some forum thread that was talking about the Float X and the TL;DR was that "it's factory set with Nitrogen to 50PSI and you never should touch it". I also found that after I decided to mess with the pressure. Fox has a Dialed video about servicing an X2 (
) and at around 8:30 it says he pumps it up to 150 PSI.
Does anyone know the correct setting or range for this? I'm not sure if 150PSI is "crazy pro down hill rider" or "average dude in his mid 30s" tune.
 

·
Boom bap ambassador
Joined
·
1,001 Posts
2016-2018 is 125 psi
2019-2020 is 125 psi
2021 is 100 psi

You can find that info in the Float X2 rebuild guides for the model year of the shock - Bike Help Center | FOX

The PSI values for the piggyback are a little hard to find in the documents based on how Fox lays it out but if you Ctrl+F/search in browser for 'IFP' you will find it.
 

·
Registered
Joined
·
12,548 Posts
Does a higher IFP pressure result in any firmer damping?
Why would FOX reccomend such low ifp pressure in the first place ?

What pressures are you all using ?

Thanks

Richie
Higher IFP pressures prevent cavitation and air ingress into the damper. But they cause more seal friction and more preload. The effect on spring-rate is minor. The one I measured was 10lb/in.

Lower IFP prssure makes them feel all nice and smooth and sensitive in a push test. That is all.
 

·
Registered
Joined
·
12,548 Posts
Preloading of what? The seals hence the higher friction?
Preloads the shock with top-out force. But also the seals with internal pressure and that's the seal drag increase.

Both are minor in the grand scheme of things. But noticable in a bench test.
 

·
Registered
Joined
·
397 Posts
Higher IFP pressures prevent cavitation and air ingress into the damper. But they cause more seal friction and more preload. The effect on spring-rate is minor. The one I measured was 10lb/in.

Lower IFP prssure makes them feel all nice and smooth and sensitive in a push test. That is all.
Yep, I do know that thanks, what I was asking collectivily of everyone is what ifp pressures are "you all using" I am aware of what the tech docs say, but if an X2 is 125psi and its sucking in air what pressure is suggested to stop the ingress of said gas into the damper oil ?
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #17 ·

Step 12 - Release the nitrogen charge by depressing the Schrader valve within the reservoir.
Step 29 - Fill the IFP chamber to 125 psi (8.6 bar) with your shock pump, then install the reservoir end cap, tightening to 30 in-lb (3.4 Nm) with your 6mm hex wrench.

So it comes from the factory with nitrogen but you refill it with air after servicing? What's the purpose of nitrogen, does it really matter?
 

·
Registered
Joined
·
12,548 Posts

Step 12 - Release the nitrogen charge by depressing the Schrader valve within the reservoir.
Step 29 - Fill the IFP chamber to 125 psi (8.6 bar) with your shock pump, then install the reservoir end cap, tightening to 30 in-lb (3.4 Nm) with your 6mm hex wrench.

So it comes from the factory with nitrogen but you refill it with air after servicing? What's the purpose of nitrogen, does it really matter?
Nitrogen is way more convenient on a production line. That's it.
 

·
Registered
Joined
·
1,013 Posts
What was the reason for older shocks like the DHX 5.0 to feel so drastically different with higher IFP pressure? I'm not sure about how much noticeable affect ifp pressure has on newer shocks but certainly my old dhx where you adjust the ifp pressure with a shock pump made huge difference to feel...what felt like more damping...all the way through the stroke.
 

·
Registered
Joined
·
12,548 Posts
What was the reason for older shocks like the DHX 5.0 to feel so drastically different with higher IFP pressure? I'm not sure about how much noticeable affect ifp pressure has on newer shocks but certainly my old dhx where you adjust the ifp pressure with a shock pump made huge difference to feel...what felt like more damping...all the way through the stroke.
The DHX5 ran a "Boost Valve" which was like the SPV that Manitou (and CVT that 5th Element) ran back in the mid 2000's. It was pressure sensitive damping. More pressure closed the base-valve more.
 
1 - 20 of 30 Posts
Top