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  • Pike burping
  • Premier Icon the00
    Free Member

    I have some 29er Pikes RCT3, 2018.5 model with Charge 2 damper, 140mm travel. These have been pretty sweet for the last year or so. It’s had a couple of lower leg services, and I’ve experimented a bit with air pressures, tokens and damping adjustments etc. I currently run quite low pressures for my weight (85psi at 85kg), and 2 tokens.

    However last weekend at CYB I noticed mid ride that the fork was very sticky – requiring a large force to get it moving. It wasn’t so bad ‘off the top’, but mid-travel was awful. In desperation I tried the fork ‘burping’ technique of sticking a zip tie down past the fork seal to remove air pressure build up form the lower leg. I was hoping for a hiss of air, but there was nothing. However the fork performance was immediately restored, so I presume that my intervention had been necessary.

    My next ride on the bike last night and immediately the forks needed the same thing. Is this something I will have to do before every ride now? What has changed that makes it necessary now, when it wasn’t an issue before? Or should I just do another lower leg service, despite the last one being only about a month ago. I don’t think the air spring is loosing pressure, so what is the cause?

    Premier Icon qwerty
    Free Member

    Isn’t this the blocked transfer port issue that can plague solo airs?

    A lower leg service making sure to clean any excess grease from the top of the air shaft head and then a liberal relube should sort. This worked for me on an old set of Revelations.

    The burping was only ever a temporary measure, the cause is still underlying.

    Premier Icon enigmas
    Free Member

    If burping the wiper seal resolves the issue temporarily then air’s migrating to the lowers on that side and acting as an additional air chamber.

    Are you experiencing any loss of pressure on the air spring? If so it’s likely the seal around the air shaft needs replacing.

    Premier Icon the00
    Free Member

    Enigmas…. that was my thought, but I can’t detect any pressure loss from the air spring.

    The ‘burping’ procedure I have heard about a lot, but I haven’t heard anything about why it might be necessary.

    Premier Icon Beagleboy
    Full Member

    I thought this was going to be like the Octopus Sex thread. Disappointed now.

    Premier Icon calv145
    Full Member

    My Pikes do this periodically. I notice straight away on the trail as the fork feels very harsh and my hands hurt. Let air out, see if forks suck up, if they do just put foot on the wheel and pull up on the bars to forcefully so extend the forks. This should clear the transfer port but to make sure, pump up to max pressure, cycle the fork enough to pass the transfer port and then set your normal pressure. Job done. I have recently serviced my air shaft and am trying what they do in the new Rockshox forks, which is to use dynamic seal grease on the air shaft and 3ml of oil on top. So far I haven’t had the same problem. I think the oil maybe stops the grease blocking the port

    Premier Icon ndthornton
    Free Member

    Isn’t this the blocked transfer port issue that can plague solo airs?

    A lower leg service making sure to clean any excess grease from the top of the air shaft head and then a liberal relube should sort. This worked for me on an old set of Revelations.

    Its a myth. how can grease that is almost liquid and meant to be there hold back tens of PSI of air pressure that exists between the positive and negative chambers. If you get a leaky tyre you don’t fix it with a light grease. Even if it were possible how does cleaning the lube off and then liberally reapplying it help.

    Dynamic air seals in the air spring however rely on grease to create a good seal and if there isn’t enough you will get air leaking from the negative spring into the lowers as the fork compresses (I have seen this in action when I forgot to grease the air shaft – eventually it pops the dust seal out if you don’t relieve the pressure). This will cause the harsh feeling forks and is remedied by a correct air spring service. I should think that this is the effect people are attributing to the transfer port issue.

    Premier Icon the00
    Free Member

    ndthornton – I think I agree with that assessment.

    I doubt my issue is between positive and negative spring chamber, because ‘burping’ at the dust seal would have no effect if that were the case.

    I have done another lower leg service this evening, but an air spring service will be by next step if necessary.

    Premier Icon Yak
    Full Member

    +1 for an airspring service with new seals. It takes only a bit more time than a lower leg service and if you are needing to burp air from the lowers it sounds like it needs doing.

    Premier Icon the00
    Free Member

    Any recommendations for where to get the bits?

    Premier Icon Yak
    Full Member

    Tftuned, bike24. Circlip pliers are useful if you haven’t got them already.

    Premier Icon the00
    Free Member

    They’re pricey then… tempted just to send them off for a full service if the seals alone are that expensive.

    Premier Icon simonloco
    Free Member

    Yes above, full service due every 12/18 month service really to keep them tip-top.
    Air seal leaking +ve/-ve chamber/ through the inside seal head into the lowers ( the seals are in contact with dirty ( & small amount of lower lube) & you’re damping oil will be a bit degraded too. They’ll feel great when you get them back.

    Premier Icon ndthornton
    Free Member

    Do you have the 2019 air spring? If not I recommend upgrading to this instead of replacing seals. It’s only £40 I think and makes a noticable difference to performance

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