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Once again, I spent some quality time debugging a slow leak and found out it was a loose valve core. I tightened it with pliers, but it raises the question, is there a situation where it is useful to be able to remove the valve core? Also, have replacement valve cores been available at some point, and do the cores have a standard thread or is it manufacturer-specific?

  • I've never had need to remove the core, and don't know if any of the tires I have use removable cores. I have dealt indirectly with "slime" in tubes, though, and consider it the devil's spawn. It's as often a cause for tire failure as it is a puncture preventative. If the purpose for removable cores is to allow sliming tubes, it's a needless purpose. – Daniel R Hicks Aug 31 '15 at 0:41
  • On a sidenote: Use loctite on the valve core and be careful with the pliers. – Michael Aug 31 '15 at 8:02
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As others have mentioned one reason is to make it easier to installed slime/sealant into a tube or tire. Typically you'll take the valve off, and use an injector to put the slime into the tire.

For tubeless tire setups, removing the valve core allows a higher volume of air to quickly get into the tire when you are first blowing it onto the rim.

Some types of valve extenders used by people with deep profile rims thread into the valve core threads.

Another reason to have removable Presta valves is they tend to be somewhat fragile so being able to replace a busted valve vs. having to replace the whole tube could potentially save a little bit of money (or allot of money if we are talking about breaking the valve core on a $150 tubular tire.)

The valve cores should be consistent from maker to maker.

  • Actually, being able to repair a tubular makes sense. And it explains why Michelin tubes don't have the removable cores: they don't make tubulars. – ojs Aug 31 '15 at 16:43
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    First, a disclosure: Michelin is one of the sponsors of my race team. While the normal Michelin Airstop tubes don't have removal cores, their latex tubes do. And Michelin does make tubular road tires, the Pro 4 Tubular which has a latex tube sewn in. – Glenn Stevens Sep 1 '15 at 2:51
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    also useful for deep-dish rims that need valve extenders. – tedder42 Sep 2 '15 at 5:44
  • I thought they'd attach to valve cap threads. But yes, valve core threads make more sense. – ojs Sep 3 '15 at 20:39
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    @ojs there are two different types of valve extenders. One threads into the valve core and the other threads onto the valve cap threads.... – Glenn Stevens Sep 7 '15 at 5:09
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I think the big benefit of a removable core is that it makes it possible to add "self-patching slime" to the tube. With a core in place the slime would likely foul the valve and make it inoperable. Otherwise, I think the removability is more an artifact of the manufacturing process – and as you've noted, not necessarily a feature.

  • Good point about slime. I doubt the theory about manufacturing process, since Michelin tubes don't have the removable core or fixing nut. – ojs Aug 30 '15 at 20:08
  • Ah, but there is surely more than one way to make the valves… I didn't mean to suggest that that was the only way. – dlu Aug 30 '15 at 20:11
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Serviceable:

  • Can get clogged with debris and can go bad
  • Install Slime

I pull the core and save it when I throw away flats.

On a new tube tighten it down before you install and if it does come loose I use just a tiny drop of Loctite.

  • Are the valve cores consistent from maker to maker? Or do you need to stick to one (or a few) kinds of tubes? – dlu Aug 30 '15 at 20:17
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    @dlu I have never had a problem. That would just be silly to have a proprietary core. – paparazzo Aug 30 '15 at 20:18
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    On the other hand, when there is no standard, manufacturers tend to come up with slightly different threads. Just try to make sense of older bottom bracket and headset standards... – ojs Aug 31 '15 at 16:45
  • @ojs On the other hand this is not a bottom bracket. You you have ANY evidence of non standard presta valve cores? – paparazzo Aug 31 '15 at 19:39
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    Not really. That's why I asked. – ojs Aug 31 '15 at 20:50

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