I am new to bikes and I realized the back tire valve is missing the top part of the valve , I inflated it but when I unscrew the pump it completely deflates. Can I buy that "screw" or I have to change the entire tube. How are they called ? Or where to buy them. If I add an adapter for for Schrader will solve the problem

  • This has happened to me once. The threaded bit broke off after over-enthusiastic pumping and the other bit subsequently disappeared into the tube. With a Presta valve, I don't know of a way to change the valve core. An adapter won't add any air keeping capability and the valve caps are intended to keep dirt out of the valve, not air in the tyre. Just buy a new inner tube.
    – DanS
    Commented Jun 18, 2015 at 9:17
  • You can typically buy them (valve) separate. I save them from blown out tubes I am throwing away.
    – paparazzo
    Commented Jun 18, 2015 at 12:34
  • Tubes are cheap. Just replace the tube and be done with it. Commented Jun 20, 2015 at 12:21

1 Answer 1


What you need is a valve core (provided the stem is threaded to take a removable valve core) [The question is, what happened to the original one?]

The cheapest option and easiest option is to just buy a new tube.

  • 1
    The schrader valve adapter requires the core to function. It uses the presta pin. Without a core, it would be a wasted 99 cents. Commented Jun 18, 2015 at 19:17
  • Right, deleted that -- must have been tired.
    – Batman
    Commented Jun 18, 2015 at 20:33
  • 1
    Too many late nights capturing thieves and recovering bicycles for the good citizens of Gotham. Commented Jun 18, 2015 at 21:31
  • Sometimes the valve core can be removed by mistake when you remove the protective plastic cap, probably if it's tightened too much.
    – Bibz
    Commented Jun 24, 2015 at 21:50

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