Presta valve stems keep blowing

"Newsgroups" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve.

Question:

Am I inserting the valve stem incorrectly? I try to align the stem perfectly centered and
perpendicular to the rim.

Also, I asked my lbs how tight to turn the ring over the stem threads, and they said "not tight at
all: leave it a little loose".

Am I missing something here, or am I just unlucky with blowouts at that spot?

TIA

Howard

If it is a wheel that you've used without any valve problems in the past, the problem must be poorly
manufactured tubes. If it is a new wheel, the problem still is probably due to poorly made tubes,
but do check for sharp edges and burrs in the rim's valve hole.

I think well made tubes should have valves that can withstand the rigors of being pumped up with
frame pumps or mini pumps and, of course floor pumps. It is very unlikely that you are doing
anything way wrong in pumping up your tires, but if not sure, review your technique with your LBS.
Perhaps you could see if your LBS has another brand of tube for you to try. If the tubes that give
problems are made in Asia, then try German Continental tubes or visa versa.

Regarding the rings, since everything stays together and works fine without them, I leave them off.
My wife, however, likes them for some reason and that's good enough for me, so I put them on her
bike, screwed on snuggly enough so they don't come off.

Steve Shapiro [email hidden]

<[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Peter Cole said:

My bet is that you have a bad batch of tubes, unless they're different brands. If they're the
same brand & lot, try something else, and throw those silly rings away.

I'm for that analysis. I find odd that people ask this question here often and always seem to
believe it is their own fault when in fact it is a manufacturing flaw. Take the tubes back to the
store and demand replacements.

I'm for this analysis too. Furthermore, the half-dozen or so failures I've had have been with a
single brand -- Specialized.

Unfortunately, it's the only brand most shops seem to sell, and they become indignant when you
suggest that such a revered brand name would sell an inferior product.

These Specialized tubes that fail with such frequency may all be from the same batch, which has been
lying around for years on bike shop shelves.

Look for "no-name" tubes, the ones with Chinese lettering on the box. They're cheaper, and
likely better.

Quoted message said:

There are always smarty responses that place the blame with the use of knurled stem retaining nuts
that come with the tube. Considering that the manufacturer offers these as useful attachments and
how many thousands of tubes, with jam nuts. have served many thousands of miles, this suggestion
is preposterous. Beyond that, I suggest those who believe this story, apply a jam nut to a stem
when the tire is completely flat, pump the tire to the usual pressure and see where the lock nut
is. It will be about 2-3mm away from the rim. 100psi does more to extend the stem than you can
reasonably do with your fingers.

Test, schmest, everyone knows you're doing it wrong... ;-)

Matt O.

From "Various"

Stem rings? Quit using them after a long cold walk home one winter @20 years ago, front flat and
could *not* get the ring off ("frozen" on?), which had been installed "barely finger tight", due to
other torque experiments to failure. Fingers cold also, removal attempts didn't warm them up any.
Presta stems need gentle treatment, just ruined my first one in about as many (20) years, my fault
due to impatience. Since it was one from a pair (or more) of like tubes that have worked fine, doubt
"defect" theory on this one at least. Or maybe that shows that even marginal ones will work fine up
to about my usual 110-5 lbs. if handled with care.

I keep the caps and rings on new tubes until I use them (easy ID), and have had people ask for them
when they see I'm not installing them. To each their own. --Tom Paterson

<< Stem rings? Quit using them after a long cold walk home one winter @20 years ago, front flat and
could *not* get the ring off ("frozen" on?), which had been installed "barely finger tight", due to
other torque experiments to failure. Fingers cold also, removal attempts didn't warm them up
any...>> <snip> --Tom Paterson

Quoted message said:

Quoted message said:

Tom if you had a patch kit along you could've easily patched the tube without removing the stem
from the rim.

Robert too late now eh

Quoted message said:

From: [email hidden] (R15757)

Quoted message said:

Tom if you had a patch kit along you could've easily patched the tube without removing the stem
from the rim.

Robert too late now eh

Ouch (a distant, faint ouch). Much, much too late, but thanks for the idea...

It was around 20-25 degrees F. outside, getting dark, maybe that's why I never thought of trying, if
indeed I was even carrying a patch kit in that weather.

Anyone ever try a patch "in the cold" and get it to stick? --TP

"Tom Paterson" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Quoted message said:

From: [email hidden] (R15757)

Quoted message said:

Tom if you had a patch kit along you could've easily patched the tube

without

Quoted message said:

Quoted message said:

removing the stem from the rim.

Robert too late now eh

Ouch (a distant, faint ouch). Much, much too late, but thanks for the

idea...

Quoted message said:

It was around 20-25 degrees F. outside, getting dark, maybe that's why I

never

Quoted message said:

thought of trying, if indeed I was even carrying a patch kit in that

weather.

Quoted message said:

Anyone ever try a patch "in the cold" and get it to stick? --TP

Sure, both on & off road. A lot of us cycle year 'round here in Boston, I've patched flats in single
digits (F), not a pleasant experience, but I think patching in the rain is worse. I have managed to
patch without removing the tube (or even the wheel) also.

Matt O'Toole said:

I'm for this analysis too. Furthermore, the half-dozen or so failures I've had have been with a
single brand -- Specialized.

Unfortunately, it's the only brand most shops seem to sell, and they

My LBS has a variety of brands of tubes (possibly the only thing of which he has a variety!). I've
been happy with Bontrager Superlight tubes (they come in a pretty silver box). Regardless of weight
(reported as 65g on the box for 700x18c-25c), they fold up very small and are easy to stuff spares
into a small space, and are as robust as anything else I've used (or maybe even better).

That's my unscientific opinion on tubes. 🙂

Quoted message said:

Matt O.

--
Rick Onanian

"Newsgroups" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve.

Question:

Am I inserting the valve stem incorrectly? I try to align the stem perfectly centered and
perpendicular to the rim.

Also, I asked my lbs how tight to turn the ring over the stem threads, and they said "not tight at
all: leave it a little loose".

Am I missing something here, or am I just unlucky with blowouts at that spot?

Are you using a floor pump or a portable pump? If it's a portable pump (except for pumps like the
topeak morph that mimics a floor pump), then your pumping technique could be to blame. If a floor
pump, then it's more likely to be a defective batch of tubes.

Andrew Muzi said:

Quoted message said:

I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve.

Quoted message said:

Quoted message said:

Question:

Quoted message said:

Quoted message said:

Am I inserting the valve stem incorrectly? I try to align the stem perfectly centered and
perpendicular to the rim.

Quoted message said:

Quoted message said:

Also, I asked my lbs how tight to turn the ring over the stem threads, and they said "not tight
at all: leave it a little loose".

Quoted message said:

Quoted message said:

Am I missing something here, or am I just unlucky with blowouts at that spot?

Quoted message said:

Why do you add the outer lockring? We don't, as we see no useful purpose.

The lock ring prevents the stem from being pushed into the wheel when pushing on many of the common
pump heads and while manually pumping with a hose-less hand pump (typically a Silca Impero of old).

Jobst Brandt [email hidden]

Rick Onanian said:

Quoted message said:

I'm for that analysis. I find odd that people ask this question here often and always seem to
believe it is their own fault when in fact it is a manufacturing flaw. Take the tubes back to the
store and demand replacements.

Quoted message said:

While it's most likely usually a manufacturing defect, Presta valves do seem to be more
breakage-prone. I've never had a Schrader valve break, nor have I seen it happen. I have had a
Presta valve break; and I rode with a group where a rider got a flat; broke the valve while
attempting to inflate; was given a tube by another rider; that valve broke; given another tube
from yet a different rider, and finally was able to inflate.

That's a bit off subject. The problem here is a stem separating from the tube rubber, not a stem
breaking off. These stem separations are all manufacturing failures.

Jobst Brandt [email hidden]

David Damerell said:

Quoted message said:

miles, this suggestion is preposterous. Beyond that, I suggest those who believe this story,
apply a jam nut to a stem when the tire is completely flat, pump the tire to the usual pressure
and see where the lock nut is. It will be about 2-3mm away from the rim. 100psi does more to
extend the stem than you can reasonably do with your fingers.

Quoted message said:

Some people then continue to do up the nut, of course.

The point is that with your fingers, you cannot exert any significant force on the stem as is
evident from the initial tightening before inflation. Therefore, this is as always an urban legend.
If it were the source of stem separations, that is the first part that would no longer be offered
with new tubes.

Jobst Brandt [email hidden]

I'm glad to see voodoo is still well and alive on wreck.bike.tech. Tossing Presta stem nuts away,
preferably over the left shoulder under a full moon will prevent leaky stems. This is a classic
interpretation of misplaced cause and effect, there being no linkage between stem separations and
jam nuts. Since the voodoo has progressed as far as it has, many people who have tossed their jam
nuts are still having stem separations while not realizing the irony of the practice.

Jobst Brandt [email hidden]

<[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I'm glad to see voodoo is still well and alive on wreck.bike.tech. Tossing Presta stem nuts away,
preferably over the left shoulder under a full moon will prevent leaky stems.

No need to throw them away if you just buy tubes without nuts. Means the pump head seals better,
too, as there's no thread.

All the stem seperations I've witnessed have been while big burly guys put new tubes in on the road,
then brace the bike against something so they can push harder on the pump (all the while bending the
poor stem out of shape).

Regards,

Suzy

Quoted message said:

Quoted message said:

Quoted message said:

I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve.

Quoted message said:

Quoted message said:

Question:

Quoted message said:

Quoted message said:

Am I inserting the valve stem incorrectly? I try to align the stem perfectly centered and
perpendicular to the rim.

Quoted message said:

Quoted message said:

Also, I asked my lbs how tight to turn the ring over the stem threads, and they said "not tight
at all: leave it a little loose".

Quoted message said:

Quoted message said:

Am I missing something here, or am I just unlucky with blowouts at that spot?

Quoted message said:

Why do you add the outer lockring? We don't, as we see no useful purpose.

The lock ring prevents the stem from being pushed into the wheel when pushing on many of the
common pump heads and while manually pumping with a hose-less hand pump (typically a Silca Impero
of old).

I've never experienced this. I always chuck the ring.

When installing a tube and inflating, I just mash on the tire opposite the stem with my thumb and
the pump head goes on fine.

Andrew Muzi said:

Why do you add the outer lockring? We don't, as we see no useful purpose.

[email hidden] replies:

Quoted message said:

The lock ring prevents the stem from being pushed into the wheel when pushing on many of the
common pump heads and while manually pumping with a hose-less hand pump (typically a Silca Impero
of old).

I haven't used lock rings on presta valves in years and haven't had a problem pressing a pump head
over the end of a valve. If the tire is flat or nearly so before attaching the pump head, I just
press down on the outside of the tire at the valve to keep the stem from disappearing into the rim.
This works the same way with Shrader valves.

--
Bill Bushnell

"R15757" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

howard wrote:

<< I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve. >>

Not quite the thread I thought it was... A couple weeks ago, after topping off the pressure, I had a
presta valve core go shooting out of the stem, bounce off the ground and leave for parts unknown!
That was the first time in about 30 years of using presta values that I had a core leave the stem...

John

Floor pump.

Tubes that have broken: Performance "Thorn-resistant" (2) Specialized (1) Schwinn
"Thorn-resistant" (1)

Am in the process of checking the hole (presta hole) for burrs or sharp edges. Will only push on the
(inner) valve stem from the outside of the tire.

Thanks all.

Howard Levinger

"Gary Young" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Newsgroups" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

I keep getting holes at the juncture of the tube and the perpendicular rubber attachment to the
threaded metal sleeve.

Question:

Am I inserting the valve stem incorrectly? I try to align the stem perfectly centered and
perpendicular to the rim.

Also, I asked my lbs how tight to turn the ring over the stem threads,

and

Quoted message said:

Quoted message said:

they said "not tight at all: leave it a little loose".

Am I missing something here, or am I just unlucky with blowouts at that spot?

Are you using a floor pump or a portable pump? If it's a portable pump (except for pumps like the
topeak morph that mimics a floor pump), then your pumping technique could be to blame. If a floor
pump, then it's more likely to be a defective batch of tubes.

In article said:

Why do you add the outer lockring? We don't, as we see no useful purpose.

Helpful when your pump is a Silca with Campy head...

In article said:

I'm for this analysis too. Furthermore, the half-dozen or so failures I've had have been with a
single brand -- Specialized.

That is exactly my experience as well!

<[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I'm glad to see voodoo is still well and alive on wreck.bike.tech. Tossing Presta stem nuts away,
preferably over the left shoulder under a full moon will prevent leaky stems. This is a classic
interpretation of misplaced cause and effect, there being no linkage between stem separations and
jam nuts. Since the voodoo has progressed as far as it has, many people who have tossed their jam
nuts are still having stem separations while not realizing the irony of the practice.

The real question is, what is the value of jam nuts for tubes?

--
Robin Hubert <[email hidden]