[bruce_wayne]

Sorry, no luck searching...
I use a Park framepump. Every now and then when inflating the first "push" seems to take a little extra effort like maybe the valve is a little stuck but once the tube takes that first push of air, it inflates no problem. This would happen very infrequently until now. I have no problems inflating the front tire but now all the sudden the rear tire, every time its low, it's like wrestling with a gorilla trying to get that first push of air to go through. I'll take the pump off and reseat it again but still no luck. Eventually, and i'm not sure why, i'll hear a little click and then the tube will take air no problem.
I'm thinking there's some kind a "airlock" maybe in the valve-I have no idea how these things are put together but it's like something is stuck or a "flap" won't open. I'll take my pump off and use my finger to release a little air to try to "free up" something or other but that doesn't work either. Now, maybe this could be a factor: the lock nut when it's fully unscrewed (opening the valve) points rather crookedly. This was done by me when learning to use a pump by trying to "rip" the pump off with both hands rather than pushing the pump away from the valve with my fingers. Maybe since that locknut is crooked, somehow the pump after it's seated isn't able to force the valve open.
Well, i'm def attributing it to a faulty valve since I'm having no problems when I inflate the front tire. So when it p's me off enough, I'll just replace with another tube.

Anybody got any ideas? Have pity on a noob:cryin:

 

[Mr. Versatile]

That happens with Presta Valves once in a while. When I unscrew the top nut I do it carefully so as not to break or bend it. Before inflating from a too low pressure, I depress the nut momentarily all the way. This almost always works for me.

A couple of more things:
1. Don't pull the pump head off the stem. Grab the rim with both hands and push the pump head off with your thumbs. It will come off much easier, faster, and straighter that way, and as a no cost bonus you won't skin up your knuckles on the spokes.
2. Unless it's an emergency I always use tubes with unthreaded valve stems. They're easier to get the pump on and off, give a better seal, and don't chew up the gasket on the pump head like threaded ones do. My favorites are Michelin, but other manufactures also make threadless stems.
re

 

[XR4Ti]

I know you said you started doing this, but the air pressure in the tire gives a tight and sometimes sticky seal in the valve. So to inflate, always give a quick little push on the valve to free it up. Yes, it shoots out some air but hey, you were pumping it up anyway.

Not sure why you'd still have problems after doing this unless you're not getting the pump on far enough. If the tire is really low and you don't have a threaded valve stem or your stem length is too short for the rim, you can press from the opposite side of the tire to prevent the valve from backing its way into the rim.

To remove the pump from the valve, I found the best way is rotate the tire so the valve is at the top (pump is upside down), release the pump lock, and strike a sharp blow to the pump right next to the tire. I just make a fist and hit the pump with the bottom of my first. Works every time, puts no lateral stress on the valve stem, no twisting, and comes off easily.

 

[bruce_wayne]

thanks, guys...That's interesting. I just looked at my bike and the rear tube, which is giving me problems, has a threaded valve stem while the front tube which inflates with no problem is threadless. huh...
I'll make sure everytime before I inflate to give a quick push on the valve and let out a little air. See if that helps.
And if the threaded valve stems chew up the pump gasket, why not just replace that tube with a threadless spare I've got lying around.

Awright...more flat rear tire repair practice!!!!!

 

[Kerry Irons]

Silicone oil

thanks, guys...That's interesting. I just looked at my bike and the rear tube, which is giving me problems, has a threaded valve stem while the front tube which inflates with no problem is threadless. huh...
I'll make sure everytime before I inflate to give a quick push on the valve and let out a little air. See if that helps.
And if the threaded valve stems chew up the pump gasket, why not just replace that tube with a threadless spare I've got lying around.

Awright...more flat rear tire repair practice!!!!!

It may be that the internals of the Presta valve need a little bit of lube. Shoot some silicone oil in there while working the valve stem up and down. You want to use silicone because regular oil will rot your inner tube.