I had a set of 2012 Fox Float RLC forks. Initially they seemed pretty good, but over time they seemed to get more harsh and I could never set them up how I wanted them. So, I replaced them with a set of Pikes. Initally I was really impressed with these. Great small bump sensitivity, good support and they used all the travel once every few rides (and 95% on every ride). I noted down my preferred settings and all was good. But over time they’ve also started to feel more harsh and (despite the pressure being the same) they use less and less travel (never more than 75% no matter how hard I try).

I think I’ve tracked the problem down to air being trapped in the lowers. Basically the air and dust seals are totally air tight.

Now, (after all that rambling) to the question. Could this have been caused by the enthusiastic use of fork juice?

It’s just something that happens with solo air forks, I think the negative spring leaks over time. An easy solution is this, but use a small thin zip tie to avoid damaging wipers
[video]https://www.youtube.com/watch?v=blHaC1mMiWM[/video]

Bigjim, interesting video cheers!…i’ve got some solo air Revs that have never given me any grief but little nuggets like that are invaluable for future trouble shooting.

Thanks. Yes, that video demonstrates the issue pretty well. Although I have to do both sides as they both trap air, which suggests that it’s not simply air leaking from the air spring.

Also, although they suggest this is a cure for the problem it isn’t really as it just brings a different problem. Releasing all the air in the lowers with the forks fully compressed like that means that you have a low pressure (semi-vacuum if you like) in the lowers, which causes the forks to suck down a bit (although the small bump sensitivity is great 🙂 ). The real problem seems to be the air tight seal and I still wonder whether using fork juice has contributed to that.

That video is utter crap!

It solves nothing, the method demonstrated leaves a vacuum in the lowers when the forks are reinflated.

If your forks are leaking air into the lowers and need burping then do it whilst at full extension, not in a semi compressed state.

Last time I saw that video someone in the know pointed out that the zip tie can do more harm than good….

If your forks are leaking air into the lowers and need burping then do it whilst at full extension, not in a semi compressed state.

If I burp them at full compression then I can’t compress them (even with no air in the air spring). Also, I don’t think it is a leak from the air spring as the same thing happens on the damper side.

I just used to slide a zip tie down without bothering with the full compression, or deflating the air spring etc, just enough to let the zip tie slide in enough. Has to be a little one though or yes you will damage the wiper. I don’t see how the damping leg can build up pressure, certainly mine never did.

To me it sounds like the real problem is that they badly need a service.

Surely the bigger problem would be lower pressure inside the fork sucking a load crap inside?

To me it sounds like the real problem is that they badly need a service.

Exactly, service and clean. Some RS forks have a little breather hole to re balance the air at full travel, this can get full of grease/crap and stop that working. When did you last do a lowers service.

Spraying the stantions with fork juice or any other similar lubricant won’t effect the anything within the fork legs if the seals are in good condition. If they’re not then as already suggested a full service is required.

when was the last time they were fully serviced?

Right, I stripped the forks down this morning (lowers and air spring, left the damper alone as it seemed to be working fine). To be honest I couldn’t see anything wrong, but gave them a good clean, put them back together and a quick spin down the track suggests that they feel a bit better. Wont know for sure until I get a chance for a proper outing later in the week though.

By the way, I discovered a way of checking whether the little groove that balances the positive and negative chambers is blocked. I’m sure I’m not the first person to think of this, but I’ll pass it on in case it’s of interest.

1. Pump the fork up to pressure (e.g. 70psi)
2. Check that the fork is fully extended. If the slot is clear then both chambers are now at 70psi
3. Sit or lean on the bike enough to compress the forks a couple of cm. The plunger is now clear of the slot and the air is trapped in the negative chamber.
4. Press the valve to release all the pressure in the positive chamber. The forks will compress and resist extending as there is now a higher pressure in the negative chamber.
5. Pull on the wheel/bridge and stem to fully extend the fork. If the slot is clear you’ll hear a short hiss as the fork reaches full extension and the air rushes out of the negative side through the slot.

If you don’t hear the hiss then either the slot is blocked or one of the seals has failed. Either way you are going to need to take it apart. Mine hissed just fine by the way, so I don’t think the problem was a blocked slot or faulty seals. In fact I’m no closer to finding out what it was really.

when was the last time they were fully serviced?

Forks have had 50 hours use since new and this was the first service.

I asked because in both cases you mention that both forks ‘over time’ became harsher. Slow degredation of performance typicaly indicates they need a full service, replace the lube, seals etc etc

Thanks. I’ll be interested to see whether just giving them a clean and some fresh oil makes any difference. If not I’ll order a set of seals and give that a go.

Your wiper seals on your Pike fork just have foam rings below them. They are just dust wipers and not designed to be an air seal. If you had air leaking from the bottom of the stanchion into the lower leg you would find that your wiper seal would pop out.

roverpig – Member

when was the last time they were fully serviced?

Forks have had 50 hours use since new and this was the first service.[/quote]

The assumption that the forks are right at the start is a big leap sometimes, there can be excess grease etc. in the forks. Sometimes doing an early first service is a good idea especially if the performance drops.

” If you had air leaking from the bottom of the stanchion into the lower leg you would find that your wiper seal would pop out”
It takes a fair bit bigger hit than you’d think for it do actually do so though

I had one o-ring out in a set of Dual Air Revs, it popped the wiper seal out just by inflating it.

Your wiper seals on your Pike fork just have foam rings below them. They are just dust wipers and not designed to be an air seal.

I think that’s the problem. They aren’t designed to be air tight, but they were and that made it impossible to set the fork up properly. Too much air in the lowers and they were harsh and only used 75% of the travel at most, too little and they sucked down. I take your point about the seals blowing off, so maybe they weren’t a perfect seal, but they were good enough to mess up the fork.

By the way, I said that I couldn’t see anything wrong when I took them apart. That’s not quite right. There was a build up of something white in the concave part below the lip of the wiper seals. I wiped it off and it felt like a thick grease. I still wonder (back to my original question) whether it was a build up of silicone grease from over enthusiastic use of fork juice, but that’s just a guess. What I do know is that the forks felt like crap on Saturday and I’m interested to see what they feel like next time I get to ride.

There was a build up of something white in the concave part below the lip of the wiper seals. I wiped it off and it felt like a thick grease

Yes this is the lubricating fork grease that you should replace when you service the fork, if it is white it is probably turning into an emulsion with water coming through the wiper. You should replace it anyway.

Yes this is the lubricating fork grease that you should replace when you service the fork, if it is white it is probably turning into an emulsion with water coming through the wiper.

That’s an interesting idea. Thanks. It’s certainly pretty wet up here. I ride this bike all year round and maybe hose it down more often than I should. So, water getting in and forming an emulsion with the grease under the wiper seal makes sense. More sense than my Fork Juice hypothesis anyway 🙂 I cleaned it off and applied some Stendec fork grease when I put the forks back together so we’ll see how it goes.