Hi.

I bought a set of Rockshox Pike RCT3 150mm (26″) of the forums a few months back to go on my Mega Tr. They were spot on, mint condition etc. They had two tokens installed.

From the off they sat about 4-5% in their travel with my desired psi of 70. They were fine a felt good.

The other day I decided to remove one token as I only weigh 70kg to see if the forks felt better. I removed it using the correct procedure. Put air back in the forks to 70psi and the forks were sitting over 30% of the sag. Inflated to 150 and had a play with them and got them back to sitting 5% sag when at 70psi.

I then read about the Rockshox Burp which involves placing a zip tie down the seal to release any blocked air. Did this tonight. Took all the air out of the fork put a zip tie in and some air did release.

Now when at 70psi the forks sits about 30% sag. Tried pumping to 150psi and letting down to 70%. You can see the forks dropping as the psi is let down! Had a play around etc but its still doing it. Its like their is a suction or something pulling the stanction down down.

Ive had to walk away from the bike before I did something daft.

Can anyone help with this problem. Ive never had problems with fox and very nearly at the point at going back to fox. They never sat in their travel and never had any issues.

Thanks

Ian

With my limited knowledge i think the groove that transfers air between the two chambers might be blocked with grease. You may need to get the air shaft out which is a simple job and clear any grease. You may also want to try pulling on the lowers to extend them fully. If you do a google search youll find a fair bit on this subject

Edit. Im assuming its sitting in 30% of travel when no rider on bike

I don’t know what the issue is, but calm down dude. Probably not a big issue, an easy fix for someone who knows what to do and fairly inexpensive. No need for throwing them out. Send to loco or someone.

You want between 20 and 30% sag. You do not want 5% sag.

Taking the token out will mean you will have a bit more sag than with the token in. So if you did really have 5% at 70psi then you would have a bit more sag at 70psi without thr token.

Although 5% sag at 70psi sounds wrong to me.

How much do you weigh fully kitted? Edit: just read 70kg. You probably want about 60psi in the fork, sat at 25% will be ideal for your weight. You may want to go 5% either side depending on how soft you like your ride.

And why are you putting a zip tie down the wiper seal?!

Also…

You can see the forks dropping as the psi is let down!

This is correct behaviour.

There is a negative air chamber, which is equalized automatically by a valve in the fork. This chamber sucks the fork down, its how your fork doesnt feel harsh or topout all the time.

I’m pretty sure he means the forks are sucking down without him on the bike.

5% at 70psi you must weigh nothing. Also at 5% and tokens in you would struggle to get through half the travel unless you set the rebound dampening to max and it packed up a bit. I think most pros who tend to have less sag run around 20%.

EDIT i guess he means they are sucking down when not on the bike.

I’m pretty sure he means the forks are sucking down without him on the bike.

Yep, and the same behaviour applies. The fork will pull down with the weight of the bike only, and with the negative air spring. Its normal.

Just to clear a point up here.

The forks sit at 5% sag when im not on the bike or anything, just sat there. I set the sag to 25% like all forks when on the bike. My previous sets of fox forks never sat in any of their travel when unweighted with the correct psi for my weight.

My forks are sat at 30% sag at the moment unweighted with 70psi. Im guessing its the charger with a blocked port. Loco do a charger service for £50. May send it off as I aint got all the tools (or time) to do a charger service myself.

Something is not right anyway.

Edited, I misunderstood.

Might be a leak between positive and negative air chamber (if the negative chamber has too much pressure relative to the positive it will suck the inners down).

As others said it sounds like the air spring not the charger.

Have you tried letting all the air out and then extending the fork by hand?

Yep, sounds like negative air spring valve issue.

Cheers for clearing up, 30% sag unweighted at 70psi is wrong for sure.

Tried pulling up with no air in. Can pull up about 40mm before it gets to hard to pull any more.

How do i solve this air spring issue then? Off to Loco/ TF Tuned?

Thanks

Mine were like that when I pumped them up way to hard once. I went for a hard ride and they fixed themselves.

Have a word with fishers I believe there have been some issues with setting up on these forks that ended up having to have the internals replaced.

I’ve bought them second hand so no warranty.

Will a hard ride only be a temp fix though? Just don’t fancy taking them out for a ride with 130mm of travel.

Plush suspension tuning any good?

By bleeding the air out the lowers you’ve created a vacuum in the lower legs which is sucking the forks down, repeat air bleed/ zip tie procedure with forks fully extended.

That air bleed trick is bollox, it doesn’t work, it upsets the balance between negative and positve chambers which is what your experiencing. By doing what you have done you’ve effectively created a secondary negative air chamber in the lowers.

Dirtydog, you are an absolute legend!!!

Done the trick and got rid of the original 5% sag issue too.

Nice one pal.

Cool.

For future ref, what is this zip tie/air bleed procedure then?.

Is there not a valve recessed in the lower leg to let the air out of the negative chamber? There is on SIDs, which rectifies this problem without zip ties and burping.

@nobeerinthefridge Basically it involves letting the air out of the forks and compressing them whilst at the same time pushing a cable tie down the side of the dust/oil seals, this releases the air displaced by the upper legs.

Problem with this is, as I mentioned above, when the forks are reinflated it creates a vacuum in the lower legs which acts like a secondary negative chamber…really not sure what the point of it is but it throws the balance out between the positive and negative air chambers, its utter bollox.

dirtydog – Is it worth doing the burp method fully inflated now and again to release any trapped air or was it just to solve my problem?

No valve in pikes to let -ve air out. My friend let air out of his whilst sat on the bike causing the -ve pressure to be higher than the +ve. This caused suck down. We just put the maximum pressure into the forks and could then pull them high enough for the equalisation dimple to let the air past, could hear the hiss as the pressure equalised.

They are single air aren’t they hence only one external valve and automatic balancing between +ve and -ve air chambers.

The vacuum in the lower fork sounds like just a consequence of a good fit stanchion dust seals. I guess it’s easier to push air out of the lower chamber past the seals than get air back in as it acts as a valve.

There’s a tiny hole in between the + and – chambers. At 0 travel air can move freely between the two. If they’re sucking down when you let the air out then this port is blocked and needs clearing. Pumping them to max and also cycling them up and down will usually clear it, if not then they need a service. Mine did this thing some months ago but have been fine since.

Bump. . I’m having the same isue. Should I try the cable tie thing? How far a strip down is required to unbloch the hole?