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  1. #1
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    New question here. Using the Fox HP pump and getting air into the Float

    I *thought* I pumped up the Float shock to 180psi when I got it on Thursday. Went out riding today, and in the parking lot, it seemed like something was wrong. *Thought* I pumped it up again to 180psi. Hit the trail. Rode 2.5hrs.

    Am now home and on the FOXHelp site, it states that it takes 6 turns to engage the pump to the schrader valve.

    First question...6 FULL turns? Maybe that seems obvious, but whatever.

    Next, the help site states that the gauge will register an air pressure in the shock when connected. I am pretty sure that this never occurred either time I went to pump it up. I didn't think it was a big deal, because I thought (and tend to still believe) that there is a check valve in the pump with the gauge being on the upstream side of it. SO...when connected, air would back fill up to the check but not register on the valve.

    Second question, am I somehow being very "dunce-ical" and not even connecting the pump right to register the initial shock pressure on the gauge, OR are FOX's instructions somehow wrong/different than what actually happens? Are you seeing shock pressure register on your gauges???

    I'm now worried that I rode around for 2.5hrs with little or no pressure back there. My friend that I rode with doesn't know a thing about FS or air shocks, so he was no help to me in the parking lot. Yes, when I set it up the SAG measurement looked to be about 1/2" (10-15mm for my weight) and @ what I *thought* I had pumped up to 180psi. I know it needs to be measured and not just what it "looked to be", but I couldn't find my tape measure the other day and I'm confident that I wasn't underestimating. Next, if I did, in fact, pump it up to 180psi and then somehow lost pressure, I guess that means the shock is pretty much F'd to start with, or is it somehow common for them to need a wearing in period where they will leak air initially but then effectively maintain seal over the life time?

    Still, my main questions are revolving around the actuall pump connection. Will greatly appreciate the help.

    Cheers.

  2. #2
    Nightriding rules SuperModerator
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    there is no check valve.... there should be a reading on the gauge (unless the pressure is too low for the gauge to read anything)

    Even on a shock the "loses no air", the initial reading after connecting the pump will be lower than the last time you pumped it, since the canister pressure equalizes with the hose pressure up to the gauge and therefore the pressure readint at the gauge is lower than the last time it was measured.

    as you had done, sag is the more reliable method for setting the shock up....it could be that the seals are damaged, or maybe just something (dirt, a hair, etc) is between the seal and shaft and the shock loses air...

  3. #3
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    Quote Originally Posted by crisillo
    there is no check valve.... there should be a reading on the gauge (unless the pressure is too low for the gauge to read anything)

    Even on a shock the "loses no air", the initial reading after connecting the pump will be lower than the last time you pumped it, since the canister pressure equalizes with the hose pressure up to the gauge and therefore the pressure readint at the gauge is lower than the last time it was measured.

    as you had done, sag is the more reliable method for setting the shock up....it could be that the seals are damaged, or maybe just something (dirt, a hair, etc) is between the seal and shaft and the shock loses air...
    Thanks for the reply. So, now...

    Ok. Took the bike out of my car this morning. Schrader cap off. Pressed in the valve stem. Got air to come out of the shock. Emptied it. Put the pump on. 6 turns. Definitely putting air into the shock just due to the sheer number of strokes it took to get it up to pressure...correlation to the amount of volume of air. Pumped it up to 185. Got on the bike. Measured with my tape measure.

    5/8" sag. Sag for me is supposed to be 10-15mm. So, my 5/8" is out of spec, but close. I weigh between 185-190. With a cameback and shoes??? Add another 10lbs?

    So, 195lbs...need to pump up to somewhere around 200psi. But, now my question becomes this...if I pumped to the pressure per the guideline, do you find that you actually have to pump more pressure than what is called for to achieve the proper sag measurement???

  4. #4
    Nightriding rules SuperModerator
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    the pressure/sag relation depends on your weight and on the leverage ratio of your frame and the guideline is only that...nothing wrong on deviating a bit from it

    I would suggest that you just adjust the pressure until you get your desired sag and write it down every time you adjust it. That way it will be easier to reproduce the settings later.

  5. #5
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    Good job!

    Quote Originally Posted by crisillo
    the pressure/sag relation depends on your weight and on the leverage ratio of your frame and the guideline is only that...nothing wrong on deviating a bit from it

    I would suggest that you just adjust the pressure until you get your desired sag and write it down every time you adjust it. That way it will be easier to reproduce the settings later.
    Cheers. Thanks for the response.

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