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Presta Valve trouble with flat tires

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Presta Valve trouble with flat tires

Old 09-03-12, 05:28 PM
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Stryfe
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Presta Valve trouble with flat tires

I have not ridden in a while and on inspecting my bike my tires were flat. They lost some air over time before which I hear is normal.
I am unscrewing presta valve all the way to proper postition and using a presta floor pump. When i try to inflate the air is not going in the tube, and i can hear it escaping at valve. The valve is also loose and when i put pump on "post" it is pushing valve in. I am locking pump properly.
I do not , and can not prime valve as there is no air in tires. If I push on valve it goes all the way back in "post" it will not stay in "open" position.
I have inflated my tires before so I know I am doing everything right - valve unscrewed to full open position, using presta pump, locking pump properly. Problem seems to be that tires are totally flat so there is no air pressure holding valve open.
Any help would be appreciated.
Thanks
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Old 09-03-12, 05:32 PM
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dddd
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Maybe the valve stem has slightly torn from the tube, creating a leak?

This is expected on bikes from storage. The smog in the air that gets in at the hole in the rim attacks the rubber.

Time for new tube(s) I think.
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Old 09-03-12, 09:18 PM
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Your problem cannot be related to the lack of pressure in the tube. The way Presta valves are designed pressure behind the valve (in the tube) pushes it closed, not open. Pushing on the valve from the outside opens it, pulling or tightening the nut to pull it up closes the valve. If what you're describing were true, the valve would serve to rapidly deflate inflated tubes.

So you need to look elsewhere. Possibly as dddd says, the tube is dried out and pulled away from the base of the valve. Or it's simply split. Usually you can hear a difference between air passing through the valve and leaking at the tube, and air not passing through and instead leaking around the pump gasket.

You summarize by saying you know what you're doing, but your description of the problem seems to indicate that you don't, or cannot explain yourself well.
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Old 09-04-12, 05:48 PM
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Thanks for responses. You and ddd were able to determine that this is a tube issue ( which is the case) from my details so you must have got the just of what I was speaking about. New to presto valves after a return to cycling after 15 years or so and these forums have been a great help. I , and others I am sure , appreciate the help from experienced cyclists as everyone was a noob at some point.
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