Tire Pressure/ Innertube Question

cameronb
cameronb Posts: 102
edited June 2012 in MTB workshop & tech
I have been using continental innertubes lately due to getting them at a cheap price. I ride about 2 miles on road to get to where ive currently been sessioning, and on the road run them at 50 psi. Everytime I've done the two miles, and let some air out, the psi is 40 as soon as i connect the pump. Ive been messing with them to see if this always happens, pumped them to 55 psi at the trial and after 10 minutes back to 40 psi? Is this just the innertubes that are poor? Or the presta valves?

Comments

  • nicklouse
    nicklouse Posts: 50,675
    It will be the pump being empty.

    Pump them up and the check them immediately. You will have the same loss.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Greer_
    Greer_ Posts: 1,716
    You may have yourself a slow puncture. I use the same tubes and mine are fine.

    Stick your inner tube in a bucket of water and look for air bubbles.
    Orbea Alma Team Carbon - Strava -Specialized Allez Sport
  • Greer_
    Greer_ Posts: 1,716
    nicklouse wrote:
    It will be the pump being empty.

    Pump them up and the check them immediately. You will have the same loss.

    Or that! Shock pumps do the same.
    Orbea Alma Team Carbon - Strava -Specialized Allez Sport
  • cameronb
    cameronb Posts: 102
    Nicklouse, do you mean that as soon as I take the head off the valve theyre at 40?
  • nicklouse
    nicklouse Posts: 50,675
    cameronb wrote:
    Nicklouse, do you mean that as soon as I take the head off the valve theyre at 40?
    No.

    When you reattach the pump.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • cameronb
    cameronb Posts: 102
    So air fills the pump when you reattach it, for example if it was 50, it goes to 40, the other 10 is in the pump? And you'd have to put that 10 back in to get it back to 50? I think I've understood it ha, thanks for your help.

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