Servicing An Air Shaft In Real Time | Mountain Bike Suspension Fork Service

– Hello, and welcome to
another realtime service video. This time we’re focusing on air springs. (whooshing sounds) In the past, we’ve done
really in-depth videos on lower leg services. So if this is all a bit
of a dark art to you, click here for Doddy’s video. It’s a really in-depth
how-to and a great way to familiarize yourself with what is quite a basic service. Today, though, we’re going to
be focusing on our air springs. Now, air springs are basically to replace what you might think inside your fork, the spring itself, with
just an air chamber that’s pressurized. This is not only very
light very adjustable, so it’s perfect for mountain biking. Now, a couple of things
you’re going to need before we even start this service. Big thing you’ll need
is some circlip pliers. These are to basically
remove the air spring from the lower of the fork. Also you can use a valve tool here, which is very useful. And some bits that we
don’t technically need, but they are very useful if you want to do the extra layer, and
that is a 12mm spanner and an 8mm Allen key. In regards to grease, you can use the dynamic seal grease from SRAM, or just something like
the butter or similar. They do recommend this
for the inner workings of their shocks and
forks, but to be honest, both will do a perfectly decent job. And, as always, Mr. Blue Towel,
just to keep things clean. So first thing’s first
is we need to remove our valve core from the top of the fork, let all the pressure out, make a note, take it out and away you go,
and put it somewhere safe. You can probably get away with doing it by just holding it down,
et cetera et cetera, but I think it’s not only easier but safer to do it removed entirely, out the way. You’re taking apart
some stuff that can hold really high pressures of air, and yeah, it’s not to be messed around with. That stuff can be pretty sketchy if you take something apart
that is even remotely charged, so yeah, be careful. Now, first thing’s
first, we’re going to get our circlip pliers,
which might not be part of the bread and butter
of a lot of toolboxes, but they’re certainly useful,
especially for suspension. You can use two picks, I suppose, but this will make it far, far easier. Now, at the bottom of our air spring, we have this retaining clip here which we’re going to get at with these. So forcing down nice and evenly, and it comes up like so. Now, this service we’re doing
is a great little add-on for a lower leg and will really help increase the performance of your fork. A lot of focus is on these seals here, these wiper seals and how
they might reduce friction, but the in diameter is quite large too, and having that big air spring, it needs to be lubed, it needs to be sure it’s nice and light in terms of action. Also, this is the part that you replace if you want to change
the travel of your forks, so it’s worth bearing in mind. Now, what we’ve got to do
here, and we’ve emptied the positive air chamber,
and it definitely is empty because there’s the valve core, but the negative might still be charged. So as we’re going to pull this off, there might indeed be
a little bit of a pop, so please don’t do it. It’s like in the cold cartoon, the guy looking down
the barrel of the gun. Maybe do it away from you. (pop) Pop. Hey presto, and there we have it. If you took out this top assembly here, where your volume spacers sit, you would be able to see
straight down the fork there. It’s really as simple as that. So the way it sits is here, is where your positive air chamber is. It equalizes, as the fork’s got
a little notch inside there, to fill your negative. Now, negative air chambers
are a real big buzzword in mountain biking at the moment, and here isn’t the stock assembly. Normally, it comes with
this spacer just inside. Now this is a topout spacer. It means that as your fork
reaches full extension, it doesn’t make any noise,
it’s nice and smooth. However, if you want
to, a nice little trick you can do if you’re
wanting Pike, such as these, or even later generations of
RockShox forks in general, is you can remove this, which increases the volume of your negative air, which will help a more fluttery stroke all through the travel. So that’s a nice little tip, and it’s not something you have to do,
but I mean, to be honest, the forks are very active
anywhere in their stroke anyway, but yeah, it’s
a nice little trick, and if you want to
remove that, you can just put the 8 mil in there, a
spanner on the end there, and away you go. That does take a small
amount of retaining compound on what is a very finely-pitched thread, but yeah, it’s worth doing. I’m just going to… Pinch that off. And that whole assembly
can slide off there. This is where you would then
remove the bottom out spacer or install it, depending how you’re going. What I’m going to do, ’cause why not, why not make it as good as it can be? And I’m just going to use SRAM butter just for simplicity’s sake. Just a little bit of
grease, make sure it’s clean before you go in, and
you can get special tools that will allow you to
grease this more effectively. It’s like a little, almost like a bullet that’s shaped on the end,
which is absolutely lovely, but you can do this at home very easily, just like I’m doing here. Just going to make sure my
finger’s nice and clean. Slide that on with the
obviously correct orientation. The writing should be at the bottom, and this is going to be really similar no matter if you’re
wanting Fox or whatever. It’s a very similar thing. Like I said, this is the
piece that you need to change should you want to change
the travel of your fork in the latest kind of generations. Yeah, so just bear in mind,
it’s real, real simple service, like I said, and on some
forks, like Suntours, they use spacers which clip onto this leg that are largely the same thing. Now… I was also saying earlier
on, sometimes they do use retaining compounds on there. I kind of get my forks
apart quite regularly, so for me it’s not such an issue, but if you’re a set and
forget sort of person, then maybe that’s worth doing. Nipped up nice and firmly there. If you’ve got a torque
wrench, may want to check the manufacturer’s guide on the website, but I think we’ll be pretty good there. And there we have it, so that’s that nice, sealed, lubed up there. It definitely feels pretty light, and we’re going to just
then lube up this seal here. I go quite firm. Sometimes these come so over-lubed, like a very generous helping
of grease from brand new, and what that means is
sometimes the equaloi– Equalizing port, the equaloizing port? The equalizing port, which
sits in the fork there, gets blocked by grease, and that means that sometimes the negative air chamber can become overcharged
and it can’t get back into the positive. That’s when your forks stick down, so if that’s the case,
then this is the service you need to do, although
when you’re pulling that out, sometimes there can be a real big pop, so it’s worth maybe covering
with a bit of rag or similar. Next, right, I’m just going to hold this up to the light here, shine it down. Light is a really useful tool as a way of inspecting to make sure
there are no nicks or scratches. From there, there
shouldn’t be anything much, but it’s a good habit to get into. Always inspect your stuff for wear. As you do that, you’re going
to become more familiar with what it should
look like, more familiar with tolerances and things like that, so it is definitely worth doing. And then, holding it nice
and firm, try to get it in. There we go. Then this bit is really important, because if this circlip
isn’t installed correctly, then you’re going to be in
a world of bother really, aren’t you? So we’re going to make sure
that’s nice and seated, there’s a definite snap. We’re just going to remove
the excess grease there. This will aid us in terms
of visual inspection, and there’s definitely a defined slot for this circlip to fit into. So we get it there. We’re going to come up with
our fingers, hold it in place, hold it down, and as simple as that. That’s installed very nicely, and make sure it’s all
the way seated around, it’s nice and flat, it’s
parallel with the top there. If it’s at a slant, it’s not in properly, and like I said, that
could go a bit wrong. So then very simply, we’re going
to reinstall this valve core, making sure it’s clean. I’m just going to be a bit naughty. It’s like almost at a dinner
party, double dipping. (whistles) Politics, man. So we’re going to put that in there. The reason I actually
like to lube those seals is it just reduces any sort
of micro tears it could get, and it’s just covering the bases, really. So there we have it. Now as we inflate this
positive air chamber, it’s going to make this leg come out back to where it was. Now a really good guide for air springs, there is a thing called bushing overlap, which is basically how far your lowers and your fork legs kind of mesh together and how deep they sit within there, which is obviously really important, but another visual guide you can do is if your air leg is
longer than your damper, so it’s way out here, then what happens is as it comes to the top of its stroke, it’s actually going to be
pulling apart that damper, so it can cause some
serious damage to your bike, and when we do change
the length of our forks, that’s one thing we really, really need to watch out for. So we always want to make sure even when they’re at full extension that the damper is just a little bit longer
than the air leg there, the air shaft. But that’s pretty much
it, and you’ll be amazed at how much difference that will make, and it only takes just
a few minutes to do. Now, is this something
you do all the time? Let us know in the comments below. As always, please don’t
forget to like and subscribe, and if you want to see the other
realtime service we’ve done, which is where we took
apart a rear RockShox shock, then click down here. It’s a bit of good fun, bit of waffle, just kind of me just yabbering on, and hopefully able to
include some tips and tricks that maybe you didn’t think of. Awesome, thanks for watching, guys.

61 Replies to “Servicing An Air Shaft In Real Time | Mountain Bike Suspension Fork Service”

  1. Does removing the topout spacer really give that much more volume? Going by the drawings in the RS service manuals, the negative chamber looks to be quite big and it also uses the volume of the air shaft itself. Removing a tiny spacer doesn't seem like it would make that big of a difference when the negative chamber is already massive.

  2. Great vid – can you do one on replacing / upgrading the damper ? Also, thought had seen that you are supposed to clean / re-grease the inside of the fork tube ?

  3. Really good tip with the bottom out bumper, will try that.
    Sometimes the shafts get stuck when pulling on the sliders when doing a lower leg service. If the damper shaft get stuck and you pull on it too hard, over extending it it, can the damper get damaged?

  4. Is anyone tried to put Fox Fluid or gearbox oil at the top of air spring? I think that Fox is doing that in thier maintenance manuals. I think it should help in constant lubrication because butter simply sticks to inner tube.
    And I don't know why but for me idea with removing this piece of rubber will increse a stroke? For like 10mm or hopefully I am wrong.

  5. I had a lot of fun taking my 2012 Reba's apart when I got them used this spring. I learned a lot about the duel air system. Problem is my Bike cave / workshop was my front porch and it's now 5 degrees out…

  6. Just had to get the air out of the neg chamber on my new lyric 170's. Scat a satisfying sound THAT makes 🔊👌😁

  7. Great vid Henry, thanks! Quick question, I did a lower leg service on my Manitou m30's, and with the new sus oil the air spring side bolt just doesn't want to tighten up. I can hear it spinning on the inside which is frustrating. Tried to pump it up to 120psi, but still no joy. Any suggestions?

  8. Some important steps missing there from the rockshox service Henry.
    Especially the orientation of the circlip, MASSIVELY important, one side has smooth edge, one sharp. Sharp MUST go outwards/down.
    Didnt look like u checked, hope by chance u got it right!

  9. You Missed cleaning out all the old grease from inside the stanchion, and clean with isopropyl, and then lightly regreasing 15cm around inside again. Key, certainly on RS. That tiny bit on the seal head is insufficient, will lead to binding later…make the fork worse after a few rides.
    Really need to be careful what gmbn recommends different to manufacturer stated steps, as will lead to problems for your average joe giving it a go. + Exposes psn.

  10. I owe pike 2020 for a week. It feels like upper legs are not slippery enough to slide in lower legs and that gives me weird sensation of having loose head set. It's like knocking sensation. My headset is definitely ok and tight.
    Is that normal on new pikes ?

  11. 8:48 – IMPORTANT Be sure to reinstall this Circlip/C-Clip in the same orientation as stock – with sharper edges facing out.

  12. Great content. Can your team service a Fox/Specialized Brain rear shock or Sram/Specialized Brain rear shock? Also, it would be very valuable to make a how-to-video on making a homemade vacuum bleeder like the one on This would be of very valuable content for the home mechanic DIY enthusiast.

  13. Great work Henry! Never done this service but your video gives me the confidence to give it a go. Great tip regarding removing the bottom out spacer.

  14. How often should forks be serviced as I’ve never bothered with it before and mine still feel fine, but yes newly serviced would probably feel very plush and nice

  15. this henry is the real GOAT, the newest shaman. He talks with chris porter, he do an everesting with no padding and an enduro, now he takes apart a fork like a master. This is the man.

  16. Worth pointing out for anyone with the pre Debonair airshaft the circlip needs to be twisted onto the raised bit. The new design on the debonair is much easier and Henry has obviously done this a few times, don’t despair if it’s more fiddly. If you change travel at the same time the new airshaft is easily worth the extra £/$/€ 10

  17. A spanner is a British wrench. I'm learning English
    watching GCN and GMBN. I'm an American, I don't speak English, but one day soon!

  18. Can you please. Please. Make a video for manitou m30 airfork. Mine is loosing air. Ill pump 85psi but the next day it only ratains around 20-25psi

  19. question, how would removing that top out bumper increase your negative air chamber size. wouldn't it reduce it because you are removing a spacer on that shaft and by doing so you effectively will allow the fork to extend further into the negative air?

  20. I literally just received my pike spring upgrade just like this one, great timing! One question: won't removing the top-out bumper make all top-outs harsh? Or does the air pressure prevent the parts from hitting anyway?

  21. I cannot see how removing the bumper increases (!) the volume of the air chamber!? The length of the chamber shrinks by the height of the bumper which will affect the chambers volume, too. Second, Iam guessing it will increase travel as more of the airshaft is exposed out of the stanchion towards the bottom of the fork.

  22. Great video – Can you please do a service on the damper side of the Pike fork, or is that not really necessary?

  23. PLEASE wear eye protection when dealing with circlips. It only takes one to ping off the end of the pliers and you'll be monocular in a second.

  24. Should you do a damper side service every time you do an airspring service? Or should one be more frequent?
    Great vid by the way, I wish I had watched this when I did my fork service.

  25. Wondering about the bit where you remove the top out bumper. I know my Luftkappe does not have one and never had any issues … but not so sure about a stock standard airspring … please give us more details on this removal ?

  26. #AskGMBNTech #AskHenry the compression adjustments on my RS revelation charger don't seem to have any effect on the fork. Doesn't seem to make it softer or harder like my revelation MoCo

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