Fork Problem

Wanderer78

Hi folks,

I've been having an ongoing issue with my fork, in order to get the preferred sag, I have to run extremely low pressures, as recommended by fox.

I've a fox 36 btw

Any ideas what could be going on?

Thank you

sparrowcar

https://www.boards.ie/discussion/2058239927/fork-problem

3 possible things come to mind...

What weight are you? You don't have to answer me but 36mm fox forks can be too much for very light riders.

Was there tokens installed before you bought it?

Is it a custom build with aggressive head angle? Sometimes if a bike is weighted towards the rear after mods (new fork with longer travel than stock or mullet set up) this can cause weighting to the rear meaning your fork won't sag properly when you check it in the attack position.

Wanderer78

https://www.boards.ie/discussion/comment/118870414#Comment_118870414

im about 80kg

it was serviced along time ago, i wasnt happy with the job, so now im thinking its packed with tokens, i have to open it to see whats going on

everything is stock on the bike, standard head angle

setting sag is a pain in the hole, theres very little consistency in the response of the fork while setting it, using the same technique, i get varying sag measurements

mad turnip

An issue I ran into a while back where at recommend settings from the manufacture the fork was extremely harsh and I too had to run a lower than expected pressure.

What had happened was that air from the air chamber had escaped into the lower leg and build up a negative pressure down there making the initial part of the fork stroke very stiff. You could tell this by getting off the bike and the fork would not return to its full length (in my case 170mm). This was very noticeable when no air was in the fork and half the travel disappeared.

In my case I fixed it by burping the fork, by inserting a ziptie down the side of the forks seals and letting the pressured air in the lower legs to escape. This solved the issue and I've no idea how the air got in there to begin with.

Wanderer78

https://www.boards.ie/discussion/comment/118871293#Comment_118871293

jesus this sounds exactly like what im experiencing, i ll give that a shot

Wailin

Is yours one of the newer fox 36's with the bleed valves on the lower legs? If so You could try that first before damaging the seals with a zip tie. Removing the lowers and doing a service is a handy job, plenty of videos about to guide you. I did my own 36 without any issues.

Wanderer78

https://www.boards.ie/discussion/comment/118876193#Comment_118876193

no mines an older version without the bleed valve, i think i ll have to give the zip tie trick a go, and see what happens, im gonna try do a lower service as well, just have to get new seals. i have a funny feeling its also packed with tokens, so i ll have to open it and see

mad turnip

https://www.boards.ie/discussion/comment/118877231#Comment_118877231

When I did it on mine, I could hear the air escape from the lowers there was that much in there.

As Wailin has pointed out if you have that bleed port that does accomplish the same thing only done correctly. This must be a bigger issue with the forks than Fox and Rockshox let on if they have added a dedicated port to resolve the issue.

Wanderer78

https://www.boards.ie/discussion/comment/118878270#Comment_118878270

have a funny feeling theres gonna be a good bit in mine also, theres a couple of videos on youtube, surprising the amount of air that can get in alright

Wailin

Anyone know how the air gets in there?

Wanderer78

https://www.boards.ie/discussion/comment/118883502#Comment_118883502

id say the movement of the fork itself would case a vacuum, sucking air in passed seals, maybe?

mad turnip

https://www.boards.ie/discussion/comment/118883502#Comment_118883502

I was told that during transportation of the fork / bike by air the pressure can increase and potentially burst in. Also storage of the fork for long periods before bike assembly in an unexpected way.

Recently a year after solving my lower leg issue I was on a spin up in the gap and I heard a sudden burst of air escape and my fork lost about 10-20 psi. By the time I got to the bottom and cycling the fork a few times the pressure had equalized itself again.

Was going to do a service but the issue hasn't come up again since. Although I am overdue a service so I'll better do it soon.

Wanderer78

burped it yesterday, good chunk of air in the valve side, nothing in the other side, but unfortunately air is getting back in very easily, unsure how, but i suspect i have a leaky seal somewhere?

im getting some oil escaping during burping also

mad turnip

https://www.boards.ie/discussion/comment/118887272#Comment_118887272

There is only air in one side of the fork, the air spring side so it escaping from one side only is expected. If air is getting back in your seals are gone and need to be replaced along with a service. Oil getting out when you burp it is probably somewhat expected didn't happen to me though.

In Dublin: expertcycles and thebikerack both service suspension.

Wanderer78

https://www.boards.ie/discussion/comment/118889939#Comment_118889939

it looks like some forks end up with air in the none air side, presumably from use. more farting about today, i think my seals are gone, way too much air getting into lower legs, way too quickly, i may have to service myself, as i wasnt happy with the only option available to me. any service recommendations in the south east?

mad turnip

https://rhsuspension.ie/

I'm not from around there so might be worth ringing a few bike shops to see if they do it or know who does. Not many places do it in Dublin. So can't imagine the SE has many options.

Wailin

https://www.boards.ie/discussion/comment/118889995#Comment_118889995

I'm from the South East myself (living in dublin) and I wouldn't know anywhere that services forks. Maybe give Altitude in Waterford a ring?

This is the guide I used to service my fork. Very clear and helpful, easy to follow: https://youtu.be/u4TH01UqEps

Wanderer78

https://www.boards.ie/discussion/comment/118891603#Comment_118891603

i actually know the lads in altitude, but to be honest, i wasnt that happy with the previous job they done on the forks, so id say i ll have to give this a go myself, thanks very much though

fatbhoy

https://www.boards.ie/discussion/comment/118889995#Comment_118889995

I've heard great things about this guy: https://rhsuspension.ie/

Richie Hayter based in Gorey. As far as I know he's an English guy who used to work in one of the proper suspension firms in England (TF Tuning or Silverfish possibly), and moved to Gorey a while back. All he does is suspension so he's a proper specialist.

Wailin

Just reading his page and services. Looks to be exactly what you need wanderer, prices look reasonable enough too when including parts.

saccades

https://www.boards.ie/discussion/comment/118885315#Comment_118885315

Aircraft pressure differential? Who told you that cobblers?

The planes are sealed so the pressure barely changes (otherwise your crisp packet would pop) and the pressure is lower at altitude, which would "suck" air out if the negligible pressure difference could overcome the seals.

It's being pumped in slowly with use on the trails.