Presta Valve ripping out of tube. Replacement valve available?
Bob Gary
I've read the article on improper pumping using a frame pump, I don't
believe this is the reason why the valve is tearing out of the tube. I
tend to do all of my inflation at home, using a floor pump. The tube
is installed with the valve sticking straight out of the rim, and the
jam nut is never tightened against the rim. Still, I just found my
mountain bike with a front flat, and upon inspection, the valve had
partially separated from the tube, at the point where the valve is
molded and enters the tube.
One of the solutions I've used over the years is to install the presta
jam nut onto the tube prior to installing the tube. In this way, the
nut is inside of the rim, and prevents the valve from being stressed
at the point where the valve is molded into the tube. But I just had
a thorn resistant tube fail at the location where the valve is molded
into the tube, because I didn't do the jam nut procedure.
Does anybody know a source where I can purchase a replacement presta
valve, so that I can salvage the tube? Years ago, (20 to be exact), I
used to buy Michelin airstop innertubes, and they used a bolted-on
presta valve. The presta valve wasn't molded into the tube, but
instead used a compression scheme to produce an airtight seal to the
tube. The valve was held in place by a nut. If I could find such a
valve, I could salvage the tube, as it is perfect in every other way.
I haven't seen the part listed in loosescrews, and none of the bike
shops I've visited know what I'm talking about
bobgaryAThotmailREMOVEdotcom
terry morse
> Occasionally, I'll have a Presta valve rip out of an innertube. While
> I've read the article on improper pumping using a frame pump, I don't
> believe this is the reason why the valve is tearing out of the tube. I
> tend to do all of my inflation at home, using a floor pump. The tube
> is installed with the valve sticking straight out of the rim, and the
> jam nut is never tightened against the rim. Still, I just found my
> mountain bike with a front flat, and upon inspection, the valve had
> partially separated from the tube, at the point where the valve is
> molded and enters the tube.
That sounds like your rim's valve hole is too big for presta. Some
shops sell grommets you can put on the valve stem inside the rim that
could solve this problem.
--
terry morse
Palo Alto, CA
Jobst Brandt
> Occasionally, I'll have a Presta valve rip out of an innertube.
> While I've read the article on improper pumping using a frame pump,
> I don't believe this is the reason why the valve is tearing out of
> the tube. I tend to do all of my inflation at home, using a floor
> pump.
These are poorly made tubes whose valve stems are not properly
vulcanized to the reinforcing pad to which they are attached before
being incorporated in the tube. That some work and others don't is
proof that they are not all susceptible.
Jobst Brandt <jbr...@hpl.hp.com>
Bob Gary
valve hole drilled in my rim being too large. The inner tube in
question was a Trek Brand thorn-resistant tube, and the markings on
the tube indicate Kenda Made in Taiwan.
bobgaryAThotmailREMOVEdotcom
kh6...@nospampe.net
Schrader valve tubes. Boy, was that quite annoying. I contacted trek to
complain.
Bob Gary <look...@nospam.com> wrote:
: Yes, this is what I suspected also. I do know it is not a case of the
: bobgaryAThotmailREMOVEdotcom
--------------------------------
Bob Masse' kh6...@PE.NET
--------------------------------
SF
turn pulls the inner tube around with it but because the valve is fixed
through the rim it can not move and seperates from the tube. Try some talcum
powder inside the tyre before you refit the tube. This allows the tyre to
turn without pulling the tube with it. Also deflate and reinflate the tyre
occasionally. A pain I know but it works.
Hope this helps,
Stewart Ferguson
www.cycletyres.co.uk
Bob Gary <look...@nospam.com> wrote in message
news:1rotosgo0ojtvagm7...@4ax.com...
> Occasionally, I'll have a Presta valve rip out of an innertube. While
> I've read the article on improper pumping using a frame pump, I don't
> believe this is the reason why the valve is tearing out of the tube. I
> tend to do all of my inflation at home, using a floor pump. The tube
> is installed with the valve sticking straight out of the rim, and the
> jam nut is never tightened against the rim. Still, I just found my
> mountain bike with a front flat, and upon inspection, the valve had
> partially separated from the tube, at the point where the valve is
> molded and enters the tube.
>
Chris Freeman
just gave me another one and said he'd send the bad one back to the
manufacturer. Works for me!
chris freeman
Jobst Brandt wrote:
> Bob Gary writes:
>
> > Occasionally, I'll have a Presta valve rip out of an innertube.
> > While I've read the article on improper pumping using a frame pump,
> > I don't believe this is the reason why the valve is tearing out of
> > the tube. I tend to do all of my inflation at home, using a floor
> > pump.
>
Jobst Brandt
> This is often caused by the tyre slipping on the rim under braking.
> This in turn pulls the inner tube around with it but because the
> valve is fixed through the rim it can not move and seperates from
> the tube. Try some talcum powder inside the tyre before you refit
> the tube. This allows the tyre to turn without pulling the tube with
> it. Also deflate and reinflate the tyre occasionally. A pain I know
> but it works.
That might coincidentally occur with tire slip, something unheard of
on road bicycles with around 100psi inflation where tubes fail as
often as elsewhere. I don't think you have cause and effect coupled
in your experience. How else do you propose that road tires with high
inflation pressure, that do not move, experience this failure?
Jobst Brandt <jbr...@hpl.hp.com>
SF
will be noticed over a period of time. If you think that your high pressure
tyres do not move gradually on the rim then please let me know what tyres
you use. As Bob stated in his first post his problem can be caused by using
certain pumps or as you state poor quality tubes. I was only giving another
explaination. This problem is more prevelant with kids bikes or poorly
maintained adult bikes where tyre pressure has not been maintained at the
correct level.
Stewart Ferguson
www.cycletyres.co.uk
Jobst Brandt <jbr...@hpl.hp.com> wrote in message
news:8mq1ks$7q5$9...@hplms2.hpl.hp.com...
Jobst Brandt
>> That might coincidentally occur with tire slip, something unheard of
>> on road bicycles with around 100psi inflation where tubes fail as
>> often as elsewhere. I don't think you have cause and effect coupled
>> in your experience. How else do you propose that road tires with high
>> inflation pressure, that do not move, experience this failure?
> As I stated. This is OFTEN caused by tyre slip. It is a gradual
> effect that will be noticed over a period of time. If you think
> that your high pressure tyres do not move gradually on the rim then
> please let me know what tyres you use.
I have not had rotational motion between tire and rim on any road tire
that I have used, and I have ridden many until the tread was gone.
That tires "move" on rims is evident from wear marks on the bead
chafing strip that imprints its image on aluminum rims, but this will
not affect the position of the stem with respect to the stem hole in
the rim. Your "gradually" dodge does not make your contention valid.
> As Bob stated in his first post his problem can be caused by using
> certain pumps or as you state poor quality tubes. I was only giving
> another explaination. This problem is more prevelant with kids
> bikes or poorly maintained adult bikes where tyre pressure has not
> been maintained at the correct level.
Stop squirming. These are faulty tubes whose stems are improperly
attached. I don't understand what interest there is in throwing this
failure at the feet of the user.
Jobst Brandt <jbr...@hpl.hp.com>
SF
has one opinion. Its yours and its right. But here goes anyway. Oh by the
way I will not be posting a respones to you next inevitable rant.
> I have not had rotational motion between tire and rim on any road tire
> that I have used, and I have ridden many until the tread was gone.
Good for you.
> That tires "move" on rims is evident from wear marks on the bead
> chafing strip that imprints its image on aluminum rims, but this will
> not affect the position of the stem with respect to the stem hole in
> the rim.
So let me get this straight. You are now saying that if the tyre does move
(contrary to what you said earlier). Then this will not effect the position
of the stem. I may be mistaken here but I have often change tyres with tubes
stuck to the inside of the tyre. You say that this will not effect the
position of the valve stem. Hmm, interesting.
> Your "gradually" dodge does not make your contention valid.
I do not know what I am trying to dodge!!
> Stop squirming. These are faulty tubes whose stems are improperly
> attached. I don't understand what interest there is in throwing this
> failure at the feet of the user.
Squirm, why would I be squirming. Unless I am mistaken or you are
telepathic, Bob did not state the quality of tube he was having a problem
with. I did agree that it could be faulty or badly made tubes. As I said
before (and I will say it again for your benefit). Now read carefully.
I was only giving another explaination.
jeeeesh, some people,
Stewart Ferguson
www.cycletyres.co.uk
Jobst Brandt
> I do not know if this is worth it, you are obviuosly one of these
> people who has one opinion. Its yours and its right. But here goes
> anyway. Oh by the way I will not be posting a respones to you next
> inevitable rant.
Please, not so petulant. If you want to make technical claims than
you better have some evidence to support your claims and then
participate in the discourse.
>> I have not had rotational motion between tire and rim on any road
>> tire that I have used, and I have ridden many until the tread was
>> gone.
> Good for you.
That doesn't address the question, which is that over long periods of
use no circumferential motion takes place on a conventional road tire
with normal inflation. "Good for you" is not part of this discussion.
>> That tires "move" on rims is evident from wear marks on the bead
>> chafing strip that imprints its image on aluminum rims, but this
>> will not affect the position of the stem with respect to the stem
>> hole in the rim.
> So let me get this straight. You are now saying that if the tyre
> does move (contrary to what you said earlier). Then this will not
> effect the position of the stem. I may be mistaken here but I have
> often change tyres with tubes stuck to the inside of the tyre. You
> say that this will not effect the position of the valve stem. Hmm,
> interesting.
Wear occurs from rotational motion of the tire bead when the casing
ovalizes as the tire bears against the road. If you inspect the bead,
you'll notice that there is a special cloth strip expressly for this
purpose and that it is not structurally connected to the casing
plies. This fretting motion has nothing to do with circumferential
movement and the textured wear marks that it causes in the aluminum
rim verify that it does its motion in place.
>> Your "gradually" dodge does not make your contention valid.
> I do not know what I am trying to dodge!!
That a road tire does not creep, gradually or at all. Don't be coy.
You needn't take the readers of this newsgroup to be unaware of these
ploys.
>> Stop squirming. These are faulty tubes whose stems are improperly
>> attached. I don't understand what interest there is in throwing this
>> failure at the feet of the user.
> Squirm, why would I be squirming. Unless I am mistaken or you are
> telepathic, Bob did not state the quality of tube he was having a
> problem with. I did agree that it could be faulty or badly made
> tubes.
That there are many tubes being sold with faulty stem adhesion has
been established by many occurrences of separations with none of the
supposed reasons you have presented. No tube shifting, inflation with
too much heat from a frame pump, overtightening the jam nut, or
running at low inflation. The opposite, that is that a tube without
this flaw cannot be made to release its stem by pulling off an
inflation chuck or frame pump, or by running it with a canted stem,
can be demonstrated.
> As I said before (and I will say it again for your benefit).
> Now read carefully.
> I was only giving another explaination.
And I ask, why do you make the effort to lay this at the feet of the
user when it is fairly well established that these are faulty tubes.
The remote possibility that the user caused this by faulty use is
presumptuous in light of other people's experience.
Jobst Brandt <jbr...@hpl.hp.com>