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  1. #1
    Senior Member
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    Grrr, trouble inflating tire...

    Hi,

    I am a new bike rider ( Sequoia Comp ). I have a middle of the
    line Specialized floor pump.

    The problem:
    I loosen the lock on the end of my Presta value and tap the
    end and get a little blast of air.

    When press the pump end onto the presta valve I can hear a tiny 'ssss' for an
    instant.

    I pull up the lock lever and try to check the pressure it is
    not uncommon for it to read '0' or some small number say 40 psi.

    If I take a stroke on the pump the pressure gauge will jump
    way high ( over 120 psi).

    I suspect that some how the Presta valve is not opening and
    I am putting all of the pressure into the hose

    What am I doing 'wrong'?

    Is it possible to find an excellent hand held pressure gauge?
    It seems like every one I look at on Amazon either has no
    reviews or terrible reviews.

    Thanks

    Jerry

  2. #2
    Dances With Cars TRaffic Jammer's Avatar
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    It's just jumping because all the pressure is still in the pump and pressed up against the valve. Give 'er a bit more and the valve will drop and air will enter the tube. If not, open the valve more and try again.

  3. #3
    Senior Member
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    Hmm,

    I have the presta valve all of the way open...

    I would have thought that attaching the pump head
    to the valve would cause the pump to show the
    pressure in the tire...

    Jerry

  4. #4
    Senior Member triplebutted's Avatar
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    This happens to me when I stick the pump head too far into the valve. Maybe pull back on the pump head a tiny bit.

  5. #5
    Rat Bastard mcoomer's Avatar
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    I've had similar trouble with my Specialized pump sometimes. With the pump locked on the valve stem press on it to make sure that it's centered on the stem and completely bottomed out. If you feel a lot of resistance on the pump downstroke you're probably not seated properly on the valve stem.

    Mike
    It's better to burn out than fade away...or slip out of your pedal and face plant on the side of the road!!!

    '06 Cannondale Prophet
    '08 Specialized S-Works Stumpjumper
    '09 Specialized S-Works Tarmac SL2

  6. #6
    Surf Bum
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    I'm not familiar with that bike so I don't know what size tires it has and what pressure you are aiming for. But if it's a road bike and you're going for over 100psi and it's already up at, say, 80psi, you might have to let more air out first before you go to pump it. The pressure inside the tube is holding the valve closed and it's hard for the pump to overcome that pressure and put more air in the tube. If you start from like 20psi you can go all the way up to over 100psi more easily. Just an fyi.

  7. #7
    Evil Genius capsicum's Avatar
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    Your probably pushing the head on too hard or too far, or not enough, before lifting the lock lever. I had this problem when I first started using my topeak joeblow pro(universal chuck) on shrader valves. A quick hiss is normal though when the tire pressurizes the hose.
    The guage should show pressure as soon as the chuck is fully connected to the valve stem.
    "Data is not the plural form of annecdote."
    "yuo ned to be deadurcated"

  8. #8
    DRF aka Thrifty Bill wrk101's Avatar
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    +1 Try adjusting pump head position. There is a sweet spot where the pump head needs to be positioned.

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