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I believe with the top Presta valve pressure release nut it should stay in the upwards position to allow the air chuck to depress the Shrader. After installing the Presta-to-Shrader adapter to the stem it is screwing down the Presta pressure release nut to its locked position. Can you tell what I'm doing wrong?

FYI...I have a matching front NOS wood rim that has the same stem and it inflates beautifully with the adapter.

So perhaps it could be an issue with adapter or its improper installation. I have new adapters in stock and they all screw the pressure tip to the locking position.

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  • Welcome to Bicycles SE. Please edit your question so we can clearly understand the specific problem. I think I know what your are asking, but before spending time to formulate an answer, we really need to have a clear understanding of the problem. I do not know what you are referring to by "the top Schrader valve pressure release nut." Is that the Presta valve nut? Schrader valves do not have nuts. Hopefully you can understand where the confusion may be here.
    – Ted Hohl
    Commented Mar 4 at 16:39
  • In short the pressure tip has been screwed up to its limit but, when installing the threaded air chuck adapter it also screws the air release tip to its locking position abd not allowing air to flow to the stem.
    – JD Douglas
    Commented Mar 4 at 16:45
  • The presta stem is a two piece configuration. The base of the stem then a treaded stud the the threaded pressure release tip that allows the shrader to open where air can flow.
    – JD Douglas
    Commented Mar 4 at 16:49
  • 1
    If I could post pictures to assist with the description I'd love to
    – JD Douglas
    Commented Mar 4 at 16:54
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    You can post pictures. On the editing bar above the text box, click the 6th icon from the left. It looks like a picture frame with two mountain peaks and a sun in the top left.
    – Weiwen Ng
    Commented Mar 4 at 17:17

2 Answers 2

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It may be a case of one or a combination of both of the following possibilities:

  • The inside diameter of the Presta (valve) to Schrader (pump head) adapter is machined too small, and therefore when screwing it onto the external thread of the Presta valve, it engages the Presta lock nut, tightening it as the adapter is tightened

  • The nut on the Presta valve is slightly larger than normal and like the first possibility, the adapter engages the larger-than-normal Presta nut, tightening it as the adapter is tightened.

Based on the successful airing up of a different tire using a different Presta valve using the same adapter, at least the second possibility seems plausible in your situation. The only practical solution is to replace the Presta valve or the tube. Some Presta valves are removable/replaceable, but not all.

This is not an uncommon occurrence, as I have experienced this issue in a few cases myself.

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I've had the entire valve assembly come loose with a Presta to Schrader adapter but not this problem you're experiencing. A similar problem to yours happens when the thin, wire shaft attached to the nut is bent, this causes a loosened nut to be misaligned and adapters will catch on this, depressing the valve and let air out when trying to install adapter. There seems to be a wide variance in tolerances of adapters. Some work well while others do not--even within the same batch/brand. One trick I use is to initially press the adapter on past the threads of the valve (ones that engage a valve cap) because the adapter actually mates with the threads of the thicker stem. So, I press the adapter past the valve onto the stem proper before turning the adapter on. This gets the adapters o-ring past the area where it can grab the valve parts and cause trouble when the adapter turns.

Finally, it's common for bike tire pumps, both the ones that are designed to be carried on the bike and the larger type that generally stay in a garage, to have the ability for the head assembly to be switched to accommodate a Presta valve without an adapter. Generally, the pump head is opened by hand and the internal pieces are switched around changing it from Schrader to Presta compatible. This is generally the best solution because you eliminate the adapter and it's problems, and, in my case, I can use my Presta compatible pressure gauge to check pressure without having to jack around with an adapter to add air between checks.

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