Presta and Schraeder Valves

[Graeme]

JohnB <[email protected]> wrote in news:[email protected]:

> The whole idea is academic anyway, as don't teh baggage handlers let the aircraft tyres down
> before take off?
>
> John B

No, you're thinking of Glasgow airport where the baggage handlers stick bricks under the
undercarriage and nick the wheels ;-)

Graeme

 

[Pete Biggs]

Just zis Guy, you know? wrote:

>> Ok but you haven't confirmed the INNER TUBES were/are of the exactly same material, width and
>> thickness. This really can make quite a difference even when used within the same tyres.
>
> They are all Michelin Airstop. That's all I know about it.

There are different sizes and versions of Airstops so there's a chance that you're not comparing
like with like.

>> I still believe most if not all air loss from tubes with any type of valves (except perhaps
>> Woods*) is from the tube itself not through the valve.
>
> It's kind of hard to get the tube up to pressure without a carcass around it, and that in turn
> makes it hard to fit in the sink ;-)

There's always the bath: stick a wheel with inflated tyre in it. In fact I'll have to try that
some time.

~PB

 

[Pete Biggs]

John Everett wrote:
> BTW, with a Schrader valve it's dead easy to check for a leak. A film of soapy water, or even
> saliva, across the end of the valve will quickly reveal any leakage.

Of course. That'll save me dunking a wheel in the bath!

~PB

 

[Dave Larrington]

pmailkeey wrote:

> Got prestas on your car too ? Mine on the car match the bike. I like standards.

No. But since a car tyre pump is of limited use for inflating high-pressure bicycle tyres, and vice-
versa, I think I can live with this apparent discrepancy.

--

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================

 

[Just Zis Guy]

"Dave Larrington" <[email protected]> wrote in message
news:[email protected]...

> > Got prestas on your car too ? Mine on the car match the bike. I like standards.

> No. But since a car tyre pump is of limited use for inflating
high-pressure
> bicycle tyres, and vice-versa, I think I can live with this apparent discrepancy.

If it please the Court, I regularly use my track pump to inflate the tyres of my mobile death
greenhouse.

It has a dual head, Schrader and Presta, as does my Topeak Road Morph.

--
Guy
===

WARNING: may contain traces of irony. Contents may settle after posting.
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[Just Zis Guy]

"John Everett" <[email protected]> wrote in message
news:[email protected]...

> >An air tank the same volume as a cycle tyre?

> As if that makes any difference. Air pressure is air pressure, independent of the containment
> vessel. A valve either leaks or it doesn't.

OK, let's say the valve leaks 1cc per hour at 120psi. Pump up a bike tyre and an aircraft tyre to
120psi. Leave for ten hours. Measure the pressure. Think about it. Remember your O level physics.

> BTW, with a Schrader valve it's dead easy to check for a leak. A film of soapy water, or even
> saliva, across the end of the valve will quickly reveal any leakage.

Unless it's very slow, in which case it will very slowly reveal any leakage.

--
Guy
===

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[Dave Larrington]

Public Biggs Announcement.

Mr. Biggs has gone mad.

First we read that he fries patches, now he wants to teach his wheels to swim...

Normal Pete Biggs will be resumed as soon as possible.

That is all.

--

The Sanity Inspector
Friern Barnet

 

[Just Zis Guy]

"Pete Biggs" <ptangerine{remove_fruit}@biggs.tc> wrote in message
news:[email protected]...

> There's always the bath: stick a wheel with inflated tyre in it. In fact I'll have to try that
> some time.

Last time I did that (and it was a Very Long Time Ago) the Schrader would, after half an hour or so,
show a distinct shiny air bubble inside the valve stem. I never saw one rise to the surface, it grew
extremely slowly, and it might have been due to the age of the tube. Prestas, from more recent (but
still a Long Time Ago) experience, don't do this.

The point being that a very slight leakage from the valve is negligible in any large system.

--
Guy
===

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[Dave Larrington]

Just zis Guy, you know? wrote:

> If it please the Court, I regularly use my track pump to inflate the tyres of my mobile death
> greenhouse.
>
> It has a dual head, Schrader and Presta, as does my Topeak Road Morph.

While this may be the case, Your Honour, motorcar tyres contain lots of air at comparatively low
pressures, while road bicycle tyres contain little air, at high pressure. Track pumps, as the name
suggests, are primarily intended to inflate skinny tyres to high pressures. M'lud will no doubt be
aware of the difference between the Mountain and Road Morph pumps. I personally have a foot-operated
pump for inflating the tyres of my motorcar, purchased for some derisory sum from Halfnords many
moons ago.

Anecdotal evidence may not be acceptable to the Court; however after Young Master Robert stuffed
Mummy English's Fraud Siesta into an oncoming motorcar while heading for Castle Combe a couple of
years ago, he was obliged to inflate the spare tyre or said motorcar with his track pump, and
maintained afterwards that this was not an exercise that he should wish to repeat any time soon.

One does not wish to ponder what might have happened had Mummy English been alone in her motorcar,
rather than accompanied by bicycle-mad #1 son, and obliged to change a tyre...

Also, Schraeder valves are /ugly/.

--

Dave Larrington - http://www.legslarry.beerdrinkers.co.uk/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================

 

[John Everett]

On Fri, 30 Jan 2004 11:37:34 -0000, "Just zis Guy, you know?"
<[email protected]> wrote:

>"John Everett" <[email protected]> wrote in message
>news:[email protected]...
>
>> >An air tank the same volume as a cycle tyre?
>
>> As if that makes any difference. Air pressure is air pressure, independent of the containment
>> vessel. A valve either leaks or it doesn't.
>
>OK, let's say the valve leaks 1cc per hour at 120psi. Pump up a bike tyre and an aircraft tyre to
>120psi. Leave for ten hours. Measure the pressure. Think about it. Remember your O level physics.

Duh!! Look at your first assumption: "let's say the valve leaks 1cc per hour at 120psi". Why should
we assume the valve is leaking? The claim in this thread is that Schrader valve are inherently leak
prone. I've seen no proof that they are.

>> BTW, with a Schrader valve it's dead easy to check for a leak. A film of soapy water, or even
>> saliva, across the end of the valve will quickly reveal any leakage.
>
>Unless it's very slow, in which case it will very slowly reveal any leakage.

Even a very slow leak will be quickly revealed by the above method.

jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

 

[Pmailkeey]

On Wed, 28 Jan 2004 00:24:14 +0000, Dave Kahn <[email protected]>
wrote:

On Tue, 27 Jan 2004 01:00:18 GMT, [email protected] )(pmailkeey) wrote: ) )> )>OT:
:they're also used on heating systems ! ) )That's why heating systems are so hard to inflate with a
:bicycle pump. )

I guess you've never tried
--
Comm again, Mike.

 

[Pmailkeey]

On Wed, 28 Jan 2004 23:03:14 +0100, "Mark South"
<[email protected]> wrote:

"Just zis Guy, you know?" <[email protected]> wrote in message
news:[email protected]... )> "pmailkeey" <[email protected]>
:wrote in message )> news:[email protected]... )> )> > All four of my bikes use
:Schrader valves. I like standards. ) )Not a flame, but: the standard is to spell it as "Schraeder"
:in ASCII, )or use \umlaut{a}.

Some time ago, I checked the web on this and Schrader was the more popular spelling. And that's how
it's spelled on the box a spare tube is in !
--
Comm again, Mike.

 

[Pmailkeey]

On Wed, 28 Jan 2004 23:03:28 +0000, "Just zis Guy, you know?"
<[email protected]> wrote:

)My experience: at 85psi a tyre fitted with Presta valves will need )re-inflating at most once
:every two weeks, one fitted with Schraeder )needs topping up at least once midweek - about three
:days before it is )down to 70psi or less. )

I have Schrader equipped 16" wheel bike tyres at~75psi. I don't need to re-inflate them as often as
every two weeks.

One thing I will say though, is that for some really odd reason bike tube manufacturers fill the
tubes with chalk dust and this gets under the valve seat preventing sealing. After about 6 months of
regular inflating, it's more or less blown out. One was so bad I put water in the pump to flush the
valve out ! That helped a lot.
--
Comm again, Mike.

 

[Pmailkeey]

On Thu, 29 Jan 2004 10:06:32 GMT, Graeme
<[email protected]> wrote:

One other possible reason for not going Presta in industrial applications )(other than ease of use
:and "why fix it if it ain't broke") is that you can )push air into a Shraeder valve a hell of a lot
:quicker than a Presta. Speed )is of the essence in many applications.

Have any of you guys seen truck places put air into truck tyres after just putting the tyre on
the wheel ?

They possibly get 10psi into a very leaky situation in less than a split second by blowing it in
between the tyre and the wheel !
--
Comm again, Mike.

 

[Pmailkeey]

On 29 Jan 2004 04:53:52 -0800, [email protected] (Guy
Chapman) wrote:

I estimate that bicycle tyre contains less than half a litre of air.

Depends how much air you pump in them

)Also consider the possibility that aircraft grade valves are better )than bicycle grade ones.

No point in doing that !

)Tourists use Presta on rims which will easily acommodate Schraeder. )Why?

Tradition ?

The obvious convenience of being able to pump your tyres up at
garages would be a strong incentive to use Schraeder if they were as )good. But tourists'
:experience is that Schraeder are *not* as good. )Schraeder tubes are cheaper, but tourists (who are
:notoriously )parsimonious) fit rims which take more expensive Presta-valved tubes.

Now there's another reason for using Schrader !
--
Comm again, Mike.

 

[Just Zis Guy]

"John Everett" <[email protected]> wrote in message
news:[email protected]...

> >OK, let's say the valve leaks 1cc per hour at 120psi. Pump up a bike
tyre
> >and an aircraft tyre to 120psi. Leave for ten hours. Measure the
pressure.
> >Think about it. Remember your O level physics.

> Duh!! Look at your first assumption: "let's say the valve leaks 1cc per hour at 120psi". Why
> should we assume the valve is leaking? The claim in this thread is that Schrader valve are
> inherently leak prone. I've seen no proof that they are.

OK, so we deal with the question of why valve leakage would be an issue on bike tyres but not on
truck or aircraft tyres by the simple expedient of pretending that valves don't leak. That has the
advantage of simplicity, I suppose...

--
Guy
===

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[Dave Kahn]

"Just zis Guy, you know?" <[email protected]> wrote in message news:<[email protected]>...
> "John Everett" <[email protected]> wrote in message
> news:[email protected]...
>
> > >An air tank the same volume as a cycle tyre?
>
> > As if that makes any difference. Air pressure is air pressure, independent of the containment
> > vessel. A valve either leaks or it doesn't.
>
> OK, let's say the valve leaks 1cc per hour at 120psi. Pump up a bike tyre and an aircraft tyre to
> 120psi. Leave for ten hours. Measure the pressure. Think about it. Remember your O level physics.

Do you really think Schraders leak at higher pressures? I thought the only disadvantage of using
them for high pressure applications was that they were a bit harder to inflate.

--
Dave...

 

[Danny Colyer]

"pmailkeey" wrote:
> Some time ago, I checked the web on this and Schrader was the more popular spelling. And that's
> how it's spelled on the box a spare tube is in !

That reminds me that I've got a couple of said tubes downstairs (not for any of my machines, you
understand, but bought as spares in case of punctures when riding with the neighbours' kids in
the summer). The boxes that these Specialized tubes came in have "Schraeder Valve Tube" written
on the sides.

So nyaa

(Also, when spellchecking this post, the Microsoft spellchecker suggested replacing "Schraeder" with
"Schrader". Which suggests to me that "Schraeder" is a better spelling).

--
Danny Colyer (the UK company has been laughed out of my reply address)
http://www.speedy5.freeserve.co.uk/danny/
"He who dares not offend cannot be honest." - Thomas Paine

 

[Dave Kahn]

On Fri, 30 Jan 2004 10:47:42 -0000, "Dave Larrington"
<[email protected]> wrote:

>Normal Pete Biggs will be resumed as soon as possible.

Woss one of them, then?

--
Dave...

Get a bicycle. You will not regret it. If you live. Mark Twain

 

[Just Zis Guy]

On 30 Jan 2004 11:29:51 -0800, [email protected] (Dave Kahn) wrote:

>Do you really think Schraders leak at higher pressures? I thought the only disadvantage of using
>them for high pressure applications was that they were a bit harder to inflate.

Looking at the web I found quite a lot of sites describing how to *stop* them leaking, so that does
tend to suggest that leaks are not uncommon.

Schraders are used in high pressure applications (e.g. aircraft tyres). One strength of Schraders is
that you can feed a lot of air through them very fast. Not an issue for bike tyres, obviously.

There are a couple of things in this thread which I don't understand: one is the "standards"
argument which would , after all, indicate that we should all standardise on heavy steel bikes with
no gears, over a million of which are turned out by one factory in India alone and which outnumber
all other bike types in the world. The other is the assertion that use of a Schrader valve on an
aircraft tyre automatically implies fitness for use on a bike tyre. The volume of air is orders of
magnitude different.

I have superficially similar tyres and tubes fitted with both Presta and Schrader valves. The
Prestas all hold pressure better. Maybe Tony is right and the Michelin Airstop tube with Prestas is
better made than the *identically priced* tube with Schraders. On the other hand, maybe others are
right and the design of the Schrader valve seat is such that it is more easily degraded by French
chalk or dust. Maybe if I cleaned the Schraders really thoroughly they would hold pressure better -
and maybe it is rather easier just to use a valve which doesn't *need* to be cleaned ;-)

Guy
===
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