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This morning I went to put air into my son's MTB tyres and found that I struggled to pump the front tyre up and couldn't get any air in the rear tyre at all.

The pump is fine - I successfully used it on my bike a few minutes prior to this.

From inspecting the valve, it looks like there's a blank plastic ring blocking it. I can press the pin in to let air out (albeit slowly):

enter image description here

I've not noticed this before. I'm guessing the inner tube's age (4 years) combined with the bike having not been used for months as meant that this ring has slipped out of place from lower down the valve stem. I've tried poking it back down (hence the marks on the wring) but have had no luck. I'm off to buy replacement tubes now.

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  • Did someone vandalise the bike by shoving chewing gum into the valve ? How does the other valve look?
    – Criggie ♦
    Commented Jun 30 at 19:31
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    That was my first thought @Criggie! The front valve was a bit clogged but I was able to get air into it. In the picture above, the surface of the black part is mottled as I've been poking at it. It was smooth originally.
    – GrandMasterFlush
    Commented Jun 30 at 21:23
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    Is that o-ring from the pump that worked earlier? Does that pump still work?
    – Paul H
    Commented Jul 1 at 17:46
  • @PaulH - I don't think so, the pump seems to be working fine and I inflated the new tube with it without any problems.
    – GrandMasterFlush
    Commented Jul 2 at 7:05

2 Answers 2

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It looks like there is black stuff in your valve.

For reference here is the anatomy of a schrader valve.
enter image description here

The valve core threads into the stem.
Here is a cutaway view
enter image description here

In the question the pictured valve has black rubbery looking stuff surrounding the pin.

Using a small nail try picking out the black stuff and see if the valve works normally.

If the valve does not work normally the valve may be damaged. The valve core can be removed and replaced by using a valve core remover or needle nose pliers if you have the right size. The goal is to grasp the flats of the valve core and turn counter clockwise.
This is a valve removal tool built into a valve cap. There are many types of valve removal tools.

enter image description here

Once the valve is working again the tube should be fine.

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UPDATE: I went out and bought a replacement tube as I didn't want to miss a day's riding, without fixing the other one and then have it fail when we were out. This morning, I followed the advice that David D gave in his answer I poked at the black object with a nail and managed to extract it. Lo and behold, it seems that it was the black o-ring that can be seen in the second image of David D's answer:

enter image description here

What I suspect has happened is that the ring has aged a bit and dislodged. I couldn't poke it back the other day, but I probably wasn't using something small enough. The valve on the front tyre looked the same, so I'll try and push that in next time I have to put air in and replace the tube if I can't. I can only image that this has happened as it's a cheap 4 year old tube. Thanks for all your suggestions and comments.

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3
  • If you can get this valve working you will have a replacement tube, handy for getting away faster after a flat.
    – Willeke ♦
    Commented Jul 2 at 8:47
  • Do you have any idea where that O-ring came from? It's definitely not a part of the valve assembly. You said your pump is ok, but have you used different pumps recently? Maybe it's from another one.
    – Torben
    Commented Jul 2 at 11:09
  • @Torben - I've just checked and the front tube valve is exactly the same. I did have another pump last year, though I think it was the barrel seal on it that failed, not the valve connector.
    – GrandMasterFlush
    Commented Jul 2 at 11:29

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