Why Nutrak Schraeder Valves Leaking?

On 27 Feb, 19:17, Chalo wrote:
Leo Lichtman wrote:

My understanding is that the main purpose of the valve core is to
hold air while you screw on the valve cap.

If that were the case, then valve caps would be strong, with effective
gaskets. *All the valve caps I've seen on bicycle tubes lately are
just for keeping filth off the valve, nothing more. *Their threads
strip before they are tight enough to seal anything.

Chalo

So you fit the plastic car valve caps with the rubber ring.
TJ

On 27 Feb, 18:58, "Leo Lichtman" wrote:
"Davy" wrote:
(clip) *I removed the inner tube and put it under water. *No
punctures but a bubble of air was released from the valve
centre every 30 seconds. *The LBS replaced it but the
replacement is worse - it leaks a bubble every 5 seconds. (clip)

^^^^^^^^^^^^^^^^^^^^
A little spit on your finger tip would have shown you the problem without
even removing the wheel from the bike. *A new valve core is an obvious fix.
I'm surprised the LBS didn't do that, rather than replacing the tube.
Furthermore, a valve cap would fix it, and also keep dirt out of the valve
stem. *Dirt in the stem gets blown in when you add air, which can cause
leakage. *My understanding is that the main purpose of the valve core is to
hold air while you screw on the valve cap.

I agree. With a shrader, the cap is the seal. With a presta, the
cap keeps the valve clean so that the valve seals.
TJ

Nick L Plate wrote:
On 27 Feb, 18:58, "Leo Lichtman" wrote:
"Davy" wrote:
(clip) I removed the inner tube and put it under water. No
punctures but a bubble of air was released from the valve
centre every 30 seconds. The LBS replaced it but the
replacement is worse - it leaks a bubble every 5 seconds. (clip)
^^^^^^^^^^^^^^^^^^^^
A little spit on your finger tip would have shown you the problem without
even removing the wheel from the bike. A new valve core is an obvious fix.
I'm surprised the LBS didn't do that, rather than replacing the tube.
Furthermore, a valve cap would fix it, and also keep dirt out of the valve
stem. Dirt in the stem gets blown in when you add air, which can cause
leakage. My understanding is that the main purpose of the valve core is to
hold air while you screw on the valve cap.

I agree. With a shrader, the cap is the seal. With a presta, the
cap keeps the valve clean so that the valve seals.
TJ

I disagree. there are good caps and bad caps but a schrader valve
should seal with no cap at all (not that you'd leave it like that.)

nate

--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

"Davy" wrote:
(clip) I removed the inner tube and put it under water. No
punctures but a bubble of air was released from the valve
centre every 30 seconds. The LBS replaced it but the
replacement is worse - it leaks a bubble every 5 seconds. (clip)

"Leo Lichtman" wrote:
^^^^^^^^^^^^^^^^^^^^
A little spit on your finger tip would have shown you the problem without
even removing the wheel from the bike. A new valve core is an obvious fix.
I'm surprised the LBS didn't do that, rather than replacing the tube.
Furthermore, a valve cap would fix it, and also keep dirt out of the valve
stem. Dirt in the stem gets blown in when you add air, which can cause
leakage. My understanding is that the main purpose of the valve core is to
hold air while you screw on the valve cap.

Nick L Plate wrote:
I agree. With a shrader, the cap is the seal. With a presta, the
cap keeps the valve clean so that the valve seals.

I'm sorry, that doesn't make any sense to me at all.
Have you ever taken a valve apart?

See also:
http://www.yellowjersey.org/PV_SECT.JPG
http://www.bikegoo.co.uk/product.php...placement_core

early version:
http://patentpending.blogs.com/paten...hrader_va.html
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On 1 Mar, 23:19, Phil W Lee phil(at)lee-family(dot)me(dot)uk wrote:


I think the major point here is that while a schraeder valves seals
perfecly ok on it's own, it's worth thinking of the dustcap as the
main seal, as it gains greater significance in your mind and helps you
remember to replace it.

Here, here.

TJ

On Sat, 28 Feb 2009 19:24:59 -0800, Nick L Plate wrote:


I agree. With a shrader, the cap is the seal. With a presta, the cap
keeps the valve clean so that the valve seals. TJ

The purpose of the presta cap is to prevent the valve from puncturing the
tube in shipping. It serves no purpose, once the tube is mounted on the
rim.

A shraeder cap's functionality varies with the type of cap. The old metal
caps provided both a seal and a valve core remover. However, they would
scratch the tube in shipping. That's why they also had put a piece of
rubber on top of the cap to protect the tube. The plastic caps still
protect the tubes in shipping and do very little else when the tube is on
the rim.

Stephen Bauman