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I recently bought a new bike and the rear tire deflates quickly every time I inflate the tube.

Now here's the thing: I inflate it fully and start to ride and the tire only deflates a bit. It seems as though when it gets to a certain pressure it doesn't deflate any further.

My tube has never deflated completely. It only loses about 60%, then stays at a consistent pressure. Could it be the valve or is it something else entirely?

  • What type of valve: Schrader (car-type) or Presta? The Presta type should not leak when correctly closes i.e. the little screw head is tight. With Schrader valves you may need to to remove the core (special tool) and replace it. Or the core might just be not screwed in tightly enough. – Carel Aug 5 '15 at 10:06
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Your insight about the pressure is interesting, but it doesn't tell us where the leak is.

Remove the tube from the bicycle.

Inflate the tube, and listen for the leak. Check the valve by sticking it in your ear.

If you can't pinpoint it's location that way, put the tube underwater and watch for a bubble stream.

If the leak is coming from the valve, you may need a new tube, or the valve core may be loose (depending on the valve type). Otherwise, it can probably be patched.

  • Don't even need to remove the tube to test the valve. – paparazzo Aug 4 '15 at 22:29
  • @Frisbee Can you describe what to do to test the valve? – dlu Aug 5 '15 at 5:14
  • I personally just apply a some spit on to the valve and if I can see small bubbles then its leaking – Code Uniquely Aug 5 '15 at 6:23
  • If you submerge the tube in water, a few drops of dish soap can make bubbles more apparent. – Benzo Aug 5 '15 at 14:43
  • @dlu Put it in water and look for bubbles. The valve is exposed. – paparazzo Aug 5 '15 at 16:40

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