Fragile presta valves?

Per David Damerell:
They increase the volume between the end of the piston stroke and the
valve, which decreases the maximum attainable pressure.

Thanks!
--
PeteCresswell

Per :
Besides, Schrader valves are commonly used for industrial use
where they hold more than 200psi.

Not to mention rear shocks on MTBs. I run mine at about 220-250 psi.
--
PeteCresswell

noname wrote:
LOL.. dude give them a shoot really... u can buy the punture sealant and ur
done... no flats whats so ever hehehe.... trust me.. tubular clincher is so
nice... get one and try it... really...

i've tried them, and while they are a nice ride, tufo's are /massively/
susceptible to punctures. i was cleaning sprayed latex off my bike
virtually every ride. tufo need to discover puncture resistant belting
like most everyone else.








"Chalo" wrote in
ups.com:


noname wrote:

I have only one thing to say.....

Clinchers SUCKKKKKKKKKKKKKKKKKKKKKKKK!!!!!!!!!!!!!!!!!!!! BIG
TIME!...

Man put a set of tufo tubular clinchers... your problems will go away
for ever!......

Yeah, that'll make fixing flats *so* much easier. Just throw them
away at $50 a pop. What a great solution!

Chalo Colina

No problems around here so far so good..





jim beam wrote in
:

noname wrote:
LOL.. dude give them a shoot really... u can buy the punture sealant
and ur done... no flats whats so ever hehehe.... trust me.. tubular
clincher is so nice... get one and try it... really...

i've tried them, and while they are a nice ride, tufo's are
/massively/ susceptible to punctures. i was cleaning sprayed latex
off my bike virtually every ride. tufo need to discover puncture
resistant belting like most everyone else.








"Chalo" wrote in
ups.com:


noname wrote:

I have only one thing to say.....

Clinchers SUCKKKKKKKKKKKKKKKKKKKKKKKK!!!!!!!!!!!!!!!!!!!! BIG
TIME!...

Man put a set of tufo tubular clinchers... your problems will go
away for ever!......

Yeah, that'll make fixing flats *so* much easier. Just throw them
away at $50 a pop. What a great solution!

Chalo Colina

leak. Besides, Schrader valves are commonly used for industrial use
where they hold more than 200psi. Neither of these valve types are
averse to holding pressures higher than found in bicycling.

I have no problem with the valve, but the attachment to the tube is
failing and causing them to blow. Essentially, the tube runs right up
the stem and if the glue lets go, the tube blows open on the stem.
Prestas may suffer other types of failure, but not THAT one, which
happens to be impossible to repair. The biggest problem with
schraders is getting a pump head onto them. The stem disappears into
the tire when you try to push the pump head over them. Prestas, being
bolted in place, do not suffer from THAT problem.

A disadvantage of the Presta valve is that it has a conical seal that
jams and prevents it from releasing. For this reason it must usually
be manually forced open before it can be pumped. For this reason,
many bicycle pumps have ruined gauges that were forced beyond their
limit when a Presta valve did not open. In contrast, Schrader valves
have a flat seal that is closed by a spring. The spring force acts
even at low pressures and makes pumping more difficult without a
special valve opener in the pump head.

A simple tap with a finger after loosening the valve lock nut is
sufficient to prevent any damage to a pump's pressure gauge.

wrote:

leak. Besides, Schrader valves are commonly used for industrial use
where they hold more than 200psi. Neither of these valve types are
averse to holding pressures higher than found in bicycling.

I have no problem with the valve, but the attachment to the tube is
failing and causing them to blow. Essentially, the tube runs right up
the stem and if the glue lets go, the tube blows open on the stem.
Prestas may suffer other types of failure, but not THAT one, which
happens to be impossible to repair.

Yes they do (if I understand you right). Poorly made Presta tubes suffer
the problem of valve debonding from tube.

The biggest problem with
schraders is getting a pump head onto them. The stem disappears into
the tire when you try to push the pump head over them. Prestas, being
bolted in place, do not suffer from THAT problem.

Bolted in place? Do you mean by the lockring (AKA jam nut)? Both types can
have or not have a lockring if the stem is threaded, as most are (some
Michelin's aren't). It's not much of a problem anyway if you press the
valve down through the tyre with your thumb, and then not a problem at all
once a decent amount of air is in.

~PB

wrote:
I have no problem with the valve, but the attachment to the tube is
failing and causing them to blow. Essentially, the tube runs right up
the stem and if the glue lets go, the tube blows open on the stem.
Prestas may suffer other types of failure, but not THAT one, which
happens to be impossible to repair. The biggest problem with

I've had plenty of Presta valves pull outta their tubes when removing the
pump from them. All different brands, too.
---
Splat

wrote:
leak. Besides, Schrader valves are commonly used for industrial use
where they hold more than 200psi. Neither of these valve types are
averse to holding pressures higher than found in bicycling.


I have no problem with the valve, but the attachment to the tube is
failing and causing them to blow. Essentially, the tube runs right up
the stem and if the glue lets go, the tube blows open on the stem.

you're over-tightening the stem keeper. tubes like michelin don't even
have threaded stems. either disgard that thing completely or make sure
it's only /barely/ tight. if you're worried about pushing the stem up
into the tire, press down on the tire where the valve is, like you
/have/ to do with the michelins.

Prestas may suffer other types of failure, but not THAT one, which
happens to be impossible to repair. The biggest problem with
schraders is getting a pump head onto them. The stem disappears into
the tire when you try to push the pump head over them. Prestas, being
bolted in place, do not suffer from THAT problem.


A disadvantage of the Presta valve is that it has a conical seal that
jams and prevents it from releasing. For this reason it must usually
be manually forced open before it can be pumped. For this reason,
many bicycle pumps have ruined gauges that were forced beyond their
limit when a Presta valve did not open. In contrast, Schrader valves
have a flat seal that is closed by a spring. The spring force acts
even at low pressures and makes pumping more difficult without a
special valve opener in the pump head.


A simple tap with a finger after loosening the valve lock nut is
sufficient to prevent any damage to a pump's pressure gauge.

I have no problem with the valve, but the attachment to the tube is
failing and causing them to blow. Essentially, the tube runs right up
the stem and if the glue lets go, the tube blows open on the stem.

you're over-tightening the stem keeper. tubes like michelin don't even
have threaded stems. either disgard that thing completely or make sure
it's only /barely/ tight. if you're worried about pushing the stem up
into the tire, press down on the tire where the valve is, like you
/have/ to do with the michelins.

What is a stem keeper? There is no such thing on my tubes that blow
on the stem. Just a plain, black rubber stem.

teschman wrote:
I had a number of these failures and I am an experienced cyclist for
many years. All failures were in the same place, at the base of the
valve stem I used floor pump to inflate, careful not to wiggle the
valve stem while inflating, checked the hole in the rim for any
burrs(there were none) and generally went crazy trying to understand
what was happening. After posting the problem to this group, I found a
number of people had the same problem with the same tubes -- light
weight road tubes by Performance Bicycle. Changed brands and not had a
problem since.
Try searching this group for previous postings by me.


Went to the LBS today (1 minute walk from my work) and they said they'd
change the inner tyre for free, as this "wasn't a normal thing, and it
ought not to have happened".
Finally a bit of luck then.

By the way, I'm not sure what the brand is but it's probably not
Performance Bicycle.

Robin.