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  1. #1
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    Air pressure for rear suspension

    How do you put correct air pressure (psi) to a rear suspension?
    After pumping air to desire psi (200 for me), I loose all air pressure while unscrewing the pump from the rear shock, Fox DHX Air 5.0. I tried pumping air to 300 psi then disconnecting but again looses most of the air pressure. Do you guys have this problem? This is my first full suspension bike. Thanks for your help.

  2. #2
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    Hmmm, that sounds kind of fishy to me. I have a Fox Float and I pump to 150 psi (my desired level) and when I disconnect the hose, I'll get a slight PFFT but thats it, no lose in pressure.

    You might have an issue with your shock, I'd recommend taking it in to your LBS, maybe they would know what to do with it/set up something with Fox to get it fixed.

    Are you using a proper suspension pump?

  3. #3
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    What kind of pump are you using? It's not unusual to loose a little air at the disconnect as judd97 said, also when you reconect the pump the air has to fill the hose to trigger the pump & that can take about 60 lbs or more.

  4. #4
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    I've fallen for that, when pumping up my shock, I thought the pump gague wasn't working properly - one pump & pressure went way up and press the bleed button, heaps of pressure out. Next time I hook the pump up, the gague isn't reading same as before.
    First make sure that you screw your pump on properly - not too tight but as finger tight as you can. Then with each pump it should let in about 3psi and with each press of the bleed button it should let out about 3psi. If it's doing that then the reading on the gague should be correct.
    That's the only little piece of advice I can offer, hopefully it solves your problem. And like others have said the little psst when taking it off is normal & just air going out of the pump hose.
    energetix



  5. #5
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    The pump came with the shock. When I pump, the air pressure gauge jumps to 50 psi for each stroke not 3 psi like you said. So this is what happens. I pumped to 200 psi. When I disconnect, hear sound of pfft. So I immediately reconnect the pump to check the air pressure. It registers at 0 psi. I don't know why. Maybe the pump is broken.

  6. #6
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    Doubble check the shrader valve inside it may not be all the way in. Otherwise like you say when you push the pump it goes to 50psi possible is not filling the shock at all, creating a preasure in the pump its self.

  7. #7
    The Machine Is Forever
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    Quote Originally Posted by toCrusher
    How do you put correct air pressure (psi) to a rear suspension?
    After pumping air to desire psi (200 for me), I loose all air pressure while unscrewing the pump from the rear shock, Fox DHX Air 5.0. I tried pumping air to 300 psi then disconnecting but again looses most of the air pressure. Do you guys have this problem? This is my first full suspension bike. Thanks for your help.
    I have a Manitou Swinger 3-Way Air on my bike. The pressures I use are as follows (I weigh 240):

    Main chamber - 165psi
    SPV Chamber - 125psi

    Using these pressures, it gives me the recommended 25% sag

    As for your shock, I think that 300psi maybe be at the limit of that shock's capabilities.

    Try looking through this manual first...

    http://www.foxracingshox.com/website...Shock_OMen.pdf

    If following those instructions doesn't help, then take it back to your LBS and have them check it out.

  8. #8
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    Quote Originally Posted by toCrusher
    The pump came with the shock. When I pump, the air pressure gauge jumps to 50 psi for each stroke not 3 psi like you said. So this is what happens. I pumped to 200 psi. When I disconnect, hear sound of pfft. So I immediately reconnect the pump to check the air pressure. It registers at 0 psi. I don't know why. Maybe the pump is broken.
    Sounds like the pump may not be connected properly - I found with my pump I even have to rotate the whole pump towards the end when I'm screwing it on to get it properly connected. After heering the pssfft when connecting the pump I've found that it needs to screw on that bit more to work properly.
    Or like Dogonfr mentioned it could be the shrader valve.
    And yes the only other possibility is that you've got a dodgy pump - if in doubt see if you can borrow one or get the LBS to try theirs.


    I've got a Giant brand pump, but I imagine they're all pretty similar anyway.
    energetix



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