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I got new Dunlop valves (modern) to replace the damaged Dunlop valves for both the front and rear tires. The valve replacement was easy for the front tire. But for some reason when it comes to rear tire, the valve is just not going into the stem.

I looked for blockage in the stem (swiped the inside of the Dunlop stem with a thin wire) and found nothing. I have searched in many places for answer but found none. Can someone tell me what am I missing?

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    Is the thread the same? Isn't the stem deformed? Sep 9, 2022 at 8:53
  • Just checking - you replaced the valve stem cores in existing tubes? The tubes themselves are okay but both valves are damaged ?
    – Criggie
    Sep 9, 2022 at 11:52
  • any reason to stick to Dunlop?
    – njzk2
    Sep 9, 2022 at 12:02
  • As a tube is not that expensive, why not replace the whole tube instead? I have had a fully metal insert that did not fit in other tubes I owned, so it may be that your tube also had an odd measurement insert. But those are rare.
    – Willeke
    Sep 11, 2022 at 11:42

2 Answers 2

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Not easy to give useful advice without pictures. Perhaps you can include some?

Here is one thought: some inserts expect a slot in the stem to prevent it slipping inside. Maybe the rear stem doesn't have this slot, and your insert does expect it?

Some stem inserts with a nodge

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  • The valves in the photo in this answer are the old fashioned kind, not the modern kind mentioned in the question.
    – Willeke
    Oct 14, 2022 at 18:49
  • Ok. Thanks for pointing out. Oct 16, 2022 at 2:15
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Not all dunlop type valves have the actual same size and minor details.

I have owned a fully metal valve insert (taken out of an old tube which got binned at the bicycle shop which replaced the wheel as well as the tube) which did not fit any of the tubes I tried it on later. (Lost it since.)

And I remember from the time when we changed from the old system, with the little tubes to the modern type with the little balls, that in some tubes you could only use the old version and not the new. The differences were often small, hard to remember after years of not having the problem.

As a tube is only a few $/£/€ why not just replace it, avoiding the mismatch of the old and new valves.

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