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I've had a bit of a hiccup with my forks. They're probably only about 25hours old max in terms of riding. Came on a 2019 nx alloy sentinel. Not serviced yet but I assume may have been sat for a while in the shop given I got the bike discounted.
Out riding on Monday I suddenly noticed the fork had firmed up and looking at the dust marks on the stanchions it was clear I was only using about half the travel I'd expect. By the end of the ride (2hours later) it was down to a quarter of the travel. The comp damping seemed to still be making a difference when I adjusted it but it was like I was running loads of extra air. Rebound was harsh. I attached the shock pump when I got in and was baffled to see it reading only 50psi compared to the 75 I'd checked it had a couple of days before. 24 hours later I can't depress the fork at all and it shows 45-50psi.
I've had a quick search about and seen people say about air escaping into the lowers or the pos/neg chambers getting in a muddle. Mostly people seemed to be worried about their fork stuck down but mine is the opposite - stuck fully extended. Read about burping the fork with a ziptie and also just dumping all the air and reinflating regularly pumping to equalise the pos/neg chambers.
As I never had to do anything on my old norco's fox forks before I started doing anything I thought I'd check in here for conspiracy theories? I've also contacted the shop where I got it and they said they'd look into it and get back to me.
I've also noticed the forks look like they're over extended and measuring the amount visible to the 10% sag point seems like it's wrong. When extended I'd expect 16mm on a 160mm fork but I'm measuring ~30mm?!
Based on reading this I guess it will need taking apart to diagnose properly but I'd be keen to know what to look out for
https://singletrackmag.com/forum/topic/burping-forks/
It seemed a bit similar to this thread where they think their fork looks over extended
https://singletrackmag.com/forum/topic/burping-forks/
Any advice appreciated
Cheers
Ian
How long have you had the bike? Sounds like a warranty issue from what you’ve put above
Thanks that's useful to hear you don't think this is just a normal thing that can happen from time to time.
yeah I discussed warranty with the shop as I only got the bike in Jan, though for one reason or another only really started getting out on it since start of march!
I'm interested to what people might think it is in case anything turns awkward with the warranty and they say act of God - not covered.
Cheers
Ian
So the shop came back saying they reckon warranty route is the best option too.
If anyone has had something like this before I'd still be interested to hear what the problem turned out to be for them.
Cheers
Ian
your negative air spring isn't being charged - does it have a hard top out?
Yeah the rebound was harsh when the fork was stiffening up on the ride but now its so firm I can't depress it at all.
let all the air out of the fork and cycle it. should move easy with no air in it. then pump it back up say 25psi at a time. cycle it gently to equalise the two air chambers. if you get to 100psi at it is still over extended then slowly depress the fork and you should hear a psst noise at the equalisation port. I had this with my pike yesterday when I swapped out the air spring fora luftkappe. just held it at the port and it equalised.
Thanks for the replies. What would cause the air to start leaking out the negative chamber then mid-ride? As I said I was at 75 a couple of days earlier and now when I attach the pump it's at 50? And it didn't just go from normal to locked out instantly, it got stiffer while I was riding and then by the next day was stuck locked out.
Forks back from SRAM after warranty repair. Job sheet just said "air assembly seals replaced". Not sure what state they were in so maybe they were shot or maybe that was just something they could replace and just discharging and re-pressurising air was all that was really needed.
It would be useful to hear from people who've had something similar happen (ie forks stuck locked out rather than the more common stuck down) or for someone to say no that's a bit of an odd one keep an eye on such and such to stop it happening again.
Will get them back on the bike and shout if I have any further problems.
Cheers
Ian
if air seals went then you'd get air flowing in the lowers.