Sticking tube valve

When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

--
Joe Riel

On 2/23/2016 8:34 PM, Joe Riel wrote:
When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

Just a guess, but I'd suspect some interference inside the head of the pump.

I'm sure it's possible, because at the start of a club ride last summer,
one woman was having trouble inflating her tires using the floor pump
she brought along. When she popped the head off to see what was wrong,
the little nut on the end of the presta valve stem had broken loose,
along with a portion of the valve stem. She installed a fresh inner
tube and tried again, and once again broke off the end of the new valve
stem.

The third tube did the trick, but probably only because I used my Zefal
HPX to pump up her tire for her.

It's hard to look inside a pump head to see what might go wrong. But
I'm sure things can go wrong in there.

--
- Frank Krygowski

On 24/02/16 11:34, Joe Riel wrote:
When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.


I use a floor pump with a head that just pushes on, so if anything it
might accidentally push the valve end in rather than cause it to stick
closed. I experience the same as you.

Maybe try a squirt of silicon lubricant into the valve body?

It has never bothered me enough to do something about it.

--
JS

On Tue, 23 Feb 2016 17:34:42 -0800, Joe Riel wrote:

When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

I've noticed the same thing and think it is the rubber valve seat
sticking. I think the "significantly higher" is at least partly a
matter of areas. A 100 PSI pressure applied to a tiny little valve is
a very little force.
--
cheers,

John B.

On Tuesday, February 23, 2016 at 8:34:45 PM UTC-5, JoeRiel wrote:
When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

--
Joe Riel

try CRC electronics cleaner as seen at Walmart auto

Joe Riel wrote in :

When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

I get that when I use my wife's Joe Blow floor pump. I will get pressure at
teh vale up to around 150 psi and the valve still will not open. I jostle
the hose a tiny bit and that will usually let air into the tube.
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO
(If you're going to e-mail me, you'll have to get "yourfinger." out.)

Andrew Chaplin writes:

Joe Riel wrote in :

When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.

I get that when I use my wife's Joe Blow floor pump. I will get pressure at
teh vale up to around 150 psi and the valve still will not open. I jostle
the hose a tiny bit and that will usually let air into the tube.

That's the pump I'm using. Coincidentally, it is my wife's.

--
Joe Riel

"James" wrote in message
...
On 24/02/16 11:34, Joe Riel wrote:
When pumping air into a presta valve, I first unscrew it completely
then depress it momentarily. The expectation is that reseating it
will prevent it from sticking closed. Alas, that is not always
effective. Too often the valve won't accept pressure until the
pressure in the pump is significantly higher than that in the tube.
What causes this sticking? Friction in the valve itself? Sometimes
I wonder if the valve somehow gets stuck on the head of the pump.


I use a floor pump with a head that just pushes on, so if anything it
might accidentally push the valve end in rather than cause it to stick
closed. I experience the same as you.

Maybe try a squirt of silicon lubricant into the valve body?

It has never bothered me enough to do something about it.

I've never used a Presta valve, so its never bothered me enough to do
something about it.