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-   -   Tubes losing air tip (https://www.bikeforums.net/showthread.php?t=1234864)

rydabent 07-17-21 07:45 AM

Tubes losing air tip
 
Sometimes presta tubes lose air pressure and you simply cannot find a puncture. Be aware that some presta tubes have a screw in valve like schrader tubes do. Check the stem closely, and if you find flats, simply tighten the core back down.

GlennR 07-17-21 07:51 AM


Originally Posted by rydabent (Post 22145411)
Sometimes presta tubes lose air pressure and you simply cannot fine a puncture. Be aware that some presta tubes have a screw in valve like schrader tubes do. Check the stem closely, and if you find flats, simply tighten the core back down.

Thanks
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Iride01 07-17-21 08:43 AM

While I hear and read about presta valves with removable stems, I've never been aware of any that passed through my hands. What brands use removable stems? Is it something they use as a marketing tactic and have displayed on their box?

And why? Other than those using tubeless setups with the valve stem mounted on the rim, I'm not certain I see their reason for being. For tubeless, I can see why one might need to change a core if the sealant gums up the valve.

While I had a valve core remover for Schrader valves, the only use for it was to let air out quicker and more completely from larger tires and tubes that would take longer to empty of air to change the tire. My 25 mm tube doesn't need much time to empty.

Just curious. I'm not hating on those with removable presta cores!

GlennR 07-17-21 08:47 AM

If you have deep rims then you might need a valve extender and then you move the core from the tube stem to the extender.

ThermionicScott 07-17-21 09:04 AM


Originally Posted by Iride01 (Post 22145468)
While I hear and read about presta valves with removable stems, I've never been aware of any that passed through my hands. What brands use removable stems? Is it something they use as a marketing tactic and have displayed on their box?

And why? Other than those using tubeless setups with the valve stem mounted on the rim, I'm not certain I see their reason for being. For tubeless, I can see why one might need to change a core if the sealant gums up the valve.

Schwalbe is one brand that uses removable valve cores. Now I'm in the practice of making sure it's screwed on tight whenever I get a new one.

Gyro 07-17-21 09:05 AM


Originally Posted by rydabent (Post 22145411)
Sometimes presta tubes lose air pressure and you simply cannot fine a puncture. Be aware that some presta tubes have a screw in valve like schrader tubes do. Check the stem closely, and if you find flats, simply tighten the core back down.

I have one that that came unscrewed when I unscrewed my presta to schrader adapter from the tube. Thread sealant has stopped it from coming back out. The bike shop I bought the tub from warned me it might happen. I guess his last supply of tubes had a few in that had this problem.

tempocyclist 07-18-21 11:49 PM


Originally Posted by Iride01 (Post 22145468)
While I hear and read about presta valves with removable stems, I've never been aware of any that passed through my hands. What brands use removable stems? Is it something they use as a marketing tactic and have displayed on their box?

And why? Other than those using tubeless setups with the valve stem mounted on the rim, I'm not certain I see their reason for being.


Continental tubes also have removable valve cores. I've had one or two come loose over the years and slowly leak air. Also had one unscrew while taking off a screw-down pump head.

They're useful if you need to use a valve extender for deeper section wheels. I've got some 40mm stemmed tubes that I pop a 40mm extension on so I can use them with my 60mm deep wheels. Sure I could just buy longer stem tubes I guess....

Milton Keynes 07-19-21 08:30 AM

I had a Presta valve core unscrew out when I tried unscrewing the cap to put air in it. That just about made me want to scrap my caps.

GhostRider62 07-19-21 08:42 AM

Schwalbe, Continental, Michelin, Vittoria, Silca, Challenge have removable cores. I carry a core replacement in my bag, it is rare but they go bad.


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