1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
mtn. biking 101
2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
3. Don't belive the hype. Just because your favorite rider or best friend rides a certain bike, that doesn't mean that's the best one for you. Have an open mind and be realistic about your needs and ability.
Results 1 to 5 of 5
  1. #1
    mtbr member
    Reputation:
    Join Date
    Apr 2008
    Posts
    32

    The FOX HP pump and Float problems

    I did post this in the suspension forum, but am not sure if that would get read as much as I think it might in the beginner's forum. So...

    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
    mtbr member
    Reputation: vk45de's Avatar
    Join Date
    Feb 2009
    Posts
    1,084
    Yes your pump will read the shock's pressure when you first connect it. I never knew about the 6 full turns either, I just turned the valve until the gauge gets air, shows pressure, and doesn't go up anymore when I turn some more. That said, you should be fine b/c there was some pressure in the shock to begin with so you're not riding w/o pressure. Assuming there was no air loss when you pump; even if you don't connect it far enough to open the schrader valve, if your pressure between valve and pump is high enough, it will open it enough to let some air in. Your shock pressure will not be the 180psi your pump shows but it will be getting air.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Apr 2008
    Posts
    32
    Quote Originally Posted by vk45de
    Yes your pump will read the shock's pressure when you first connect it. I never knew about the 6 full turns either, I just turned the valve until the gauge gets air, shows pressure, and doesn't go up anymore when I turn some more. That said, you should be fine b/c there was some pressure in the shock to begin with so you're not riding w/o pressure. Assuming there was no air loss when you pump; even if you don't connect it far enough to open the schrader valve, if your pressure between valve and pump is high enough, it will open it enough to let some air in. Your shock pressure will not be the 180psi your pump shows but it will be getting air.
    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
    mtbr member
    Reputation: Fuel_81's Avatar
    Join Date
    Aug 2007
    Posts
    65
    That can happen. The air pressure they give you is a starting point. To achieve the correct amount of sag you may have to add more or less air. Correct sag is ultimately what your trying to achieve.

  5. #5
    *****************
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,379
    If your sag is supposed to be 10-15 mm then what's so wrong with .625 of an inch, which is only 15.9 mm? Probably be easier just to use a metric measure, too. Sounds pretty good to me unless you want a firmer ride or bottom it out too much with that setting. Guidelines are just that, finding what works for you best takes a little experimentation (and I'd say in small increments of say 5 lbs at a time).

    As far as screwing on a pump to a shock valve, generally you want to screw on the pump head until you get air pressure registered and a partial turn past that for a firm connection but without overtightening it. Your pressure reading will likely be lower than where you last set it at is it takes some air pressure to make the gauge register.
    "...the people get the government they deserve..."
    suum quique

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •