What am I doing wrong???

GRRRR!!! Ok, I'm still learning about all this bike stuff. I recently got a flat, first of many I am
sure, and went to patch it. Got the rear wheel off just fine, found the hole, patched it, got wheel
back on just fine. Started pumping up the tire and everything went well. Right about 105psi, I heard
the dreaded "psssssssst." DANGIT!!! Take everything off, undo the tire off the wheel, take tube out,
look for hole. Lo and behold, the problem is that where the stem meets the tube, it looks like has
been cut by the metal of the wheel. DANGIT!!! I chalk it up to the fact that I have hand tightened
the collet (I think that's what it is called) on the stem too much. As I was pumping up the tire,
the collet seemed to pull away from the rim so I would tighten it down progressively. So off to the
LBS I go looking for a new tube. Get tube, bring it home. Get it on wheel. Put on tire. Inflate
away. While I am inflating it, things are going well. When I am about 2 strokes from stopping, I
hear the same dreaded "psssssst"!!!! Did I mention I was 2 stokes from stopping?!?!? Commence with
the expletives. Finish expletives. Apologize to mothers with children playing around neighborhood,
including wife. Take wheel off, take tire off, take tube out. Examine tube. Find SAME, EXACT cut on
tube where stem meets tube. At this point, I am thinking I am doing something wrong. Am I pushing
down too hard on the pump to keep it from popping off stem? Am I too vigorous in my pumping? I've
never had that problem before. So after I cool down, I start looking at the wheel again. I find that
the wheel has some tape along the inside of it. It's like very heavy athletic tape or something all
along the wheel. I think it is rim tape? Well its nice all along the rim EXCEPT right around the
hole that the stem fits through. I think I have found my culprit. Is this rim tape a necessity? I
think it is at this point. Is this my problem? The lack of rim tape around the hole for the stem?
ANY advice/info is greatly appreciated.

 

<[email protected]> wrote in message news:[email protected]...
> GRRRR!!! Ok, I'm still learning about all this bike stuff. I recently got a flat, first of many I
> am sure, and went to patch it. Got the rear wheel off just fine, found the hole, patched it, got
> wheel back on just fine. Started pumping up the tire and everything went well. Right about 105psi,
> I heard the dreaded "psssssssst." DANGIT!!! Take everything off, undo the tire off the wheel, take
> tube out, look for hole. Lo and behold, the problem is that where the stem meets the tube, it
> looks like has been cut by the metal of the wheel. DANGIT!!! I chalk it up to the fact that I have
> hand tightened the collet (I think that's what it
is
> called) on the stem too much. As I was pumping up the tire, the collet seemed to pull away from
> the rim so I would tighten it down progressively. So off to the LBS I go looking for a new tube.
> Get tube, bring it home.
Get
> it on wheel. Put on tire. Inflate away. While I am inflating it, things
are
> going well. When I am about 2 strokes from stopping, I hear the same
dreaded
> "psssssst"!!!! Did I mention I was 2 stokes from stopping?!?!? Commence with the expletives.
> Finish expletives. Apologize to mothers with children playing around neighborhood, including wife.
> Take wheel off, take tire off, take tube out. Examine tube. Find SAME,
EXACT
> cut on tube where stem meets tube. At this point, I am thinking I am doing something wrong. Am I
> pushing down too hard on the pump to keep it from popping off stem? Am I too vigorous
in
> my pumping? I've never had that problem before. So after I cool down, I start looking at the wheel
> again. I find that the wheel has some tape along the inside of it. It's like very heavy athletic
> tape or something all along the wheel. I think it is rim tape? Well its
nice
> all along the rim EXCEPT right around the hole that the stem fits through.
I
> think I have found my culprit. Is this rim tape a necessity? I think it is at this point. Is this
> my problem? The lack of rim tape around the hole for the stem? ANY advice/info is greatly
> appreciated.
>
>

Rim tape is pretty much a necessity. Package strapping tape or electrical will work fine as well.
And loose the presta nut "collet". Pinch the tire there to keep the presta fitting from pushing into
the rim when you attach your pump.

Mike - BTDT

 

anonymous writes anonymously:

> OK, I'm still learning about all this bike stuff. I recently got a flat, first of many I am sure,
> and went to patch it. Got the rear wheel off just fine, found the hole, patched it, got wheel back
> on just fine. Started pumping up the tire and everything went well. Right about 105psi, I heard
> the dreaded "psssssssst." DANGIT!!!

It's not OK. Just be civil and admit who you are. Spammers do not read signature lines so that
excuse for anonymity doesn't hold.

> When I am about 2 strokes from stopping, I hear the same dreaded "psssssst"!!!!

> Did I mention I was 2 stokes from stopping?!?!?

No, but so what?

> Take wheel off, take tire off, take tube out. Examine tube. Find SAME, EXACT cut on tube where
> stem meets tube.

You have a manufacturing defect in the tube, the common stem separation effect that cannot be easily
fixed. You should take it to your bicycle shop and demand a new one. This has been going on for a
few years and everyone chastises himself for having done something wrong. It is a faulty tube.
That's it!

> At this point, I am thinking I am doing something wrong. Am I pushing down too hard on the
> pump to keep it from popping off stem? Am I too vigorous in my pumping? I've never had that
> problem before.

A classic response, that will be reinforced by others responding to you posting who also believe it
can only be operator error. These are faulty tubes and should be recognized as such.

> So after I cool down, I start looking at the wheel again. I find that the wheel has some tape
> along the inside of it. It's like very heavy athletic tape or something all along the wheel. I
> think it is rim tape? Well its nice all along the rim EXCEPT right around the hole that the stem
> fits through. I think I have found my culprit.

Rim tape prevents the inflated tube from stretching into the spoke holes in the rim and being
punctured by tips of spokes protruding from spoke nipples. It is an essential part of a clincher
wheel. It has no effect around the stem, there being no recess into which the tube can expand. That
is also why tubes have a reinforced section surrounding the stem.

You might want to read about patching procedures and how to avoid leaky patches at:

http://draco.acs.uci.edu/rbfaq/FAQ/8b.1.html

Jobst Brandt [email protected] Palo Alto CA

 

In article <[email protected]>, <[email protected]> writes:

snip
>Take wheel off, take tire off, take tube out. Examine tube. Find SAME, EXACT cut on tube where stem
>meets tube. At this point, I am thinking I am doing something wrong. Am I pushing down too hard on
>the pump to keep it from popping off stem? Am I too vigorous in my pumping? I've never had that
>problem before. So after I cool down, I start looking at the wheel again. I find that the wheel has
>some tape along the inside of it. It's like very heavy athletic tape or something all along the
>wheel. I think it is rim tape? Well its nice all along the rim EXCEPT right around the hole that
>the stem fits through. I think I have found my culprit. Is this rim tape a necessity? I think it is
>at this point. Is this my problem? The lack of rim tape around the hole for the stem? ANY
>advice/info is greatly appreciated.

I just make the lock ring on the valve stem finger tight, I do not continue to tighten it. It sounds
like you could have an edge on the valve stem hole in the rim that is cutting the tube. Check for
burrs and sharp edges and deal with them.

That rim tape is essential. It covers the holes that spoke nipples go through.
If you take that off you won't get to within two strokes of full pressure.

Tom Gibb <[email protected]

 

<[email protected]> wrote in message news:[email protected]...
> GRRRR!!! Ok, I'm still learning about all this bike stuff. I recently got a flat, first of many I
> am sure, and went to patch it. Got the rear wheel off just fine, found the hole, patched it, got
> wheel back on just fine. Started pumping up the tire and everything went well. Right about 105psi,
> I heard the dreaded "psssssssst." DANGIT!!! Take everything off, undo the tire off the wheel, take
> tube out, look for hole. Lo and behold, the problem is that where the stem meets the tube, it
> looks like has been cut by the metal of the wheel. DANGIT!!! I chalk it up to the fact that I have
> hand tightened the collet (I think that's what it
is
> called) on the stem too much. As I was pumping up the tire, the collet seemed to pull away from
> the rim so I would tighten it down progressively. So off to the LBS I go looking for a new tube.
> Get tube, bring it home.
Get
> it on wheel. Put on tire. Inflate away. While I am inflating it, things
are
> going well. When I am about 2 strokes from stopping, I hear the same
dreaded
> "psssssst"!!!! Did I mention I was 2 stokes from stopping?!?!? Commence with the expletives.
> Finish expletives. Apologize to mothers with children playing around neighborhood, including wife.
> Take wheel off, take tire off, take tube out. Examine tube. Find SAME,
EXACT
> cut on tube where stem meets tube. At this point, I am thinking I am doing something wrong. Am I
> pushing down too hard on the pump to keep it from popping off stem? Am I too vigorous
in
> my pumping? I've never had that problem before. So after I cool down, I start looking at the wheel
> again. I find that the wheel has some tape along the inside of it. It's like very heavy athletic
> tape or something all along the wheel. I think it is rim tape? Well its
nice
> all along the rim EXCEPT right around the hole that the stem fits through.
I
> think I have found my culprit. Is this rim tape a necessity? I think it is at this point. Is this
> my problem? The lack of rim tape around the hole for the stem? ANY advice/info is greatly
> appreciated.
>
>

The usual pattern is to punch a hole about 60mm from the end of the tape for the valve and then wrap
the rim, cutting the end with a 20-30m overlap. That way there's no gap in the tape near the valve.

That being said I doubt it is the problem. It just looks neater done that way.

We do not use valve rings here ( At least on valves - we have a box of them for use as washers. They
are nice for keeping a rack mount bolt out of the chain). I haven't ever seen a need for them
although mountain bike riders sometimes claim their valves fall into the rim without a ring. I don't
know about that.

At any rate, for today dump the valve ring.

When you inflate the tube, are you careful to press between your hands, cupping the rim/valve with
one hand so you do not press against the side of the valve stem? ( I am assuming you're using an
express pump without a hose. If your pump has a hose, none of that is relevant)

If there is some sharp edge inside your rim unprotected by the tape, correct that. Briefly reviewing
rim liners, solid-section rims in which the nipples stick up inside the tire channel require a
rubber rim liner. Make sure it is skinny enough to stay off the tire bead seat. Cotton tapes in that
style rim will cut through from the nipple slots when truing. Hollow-section rims which have
recesses for the nipples require a polyurethane or cotton cloth liner to prevent the tube from
herniating into those recesses. Pull the cotton tape tight when you wrap it so it doesn't fall into
the nipple recesses itself. Ensure the tape covers the entire width of the nipple recess without
occluding the tire bead seat. (There are several widths available in all three materials.) On some
rims this is not possible as the holes extend all the way to the edge, in which event you're screwed
and must settle for an overly wide tape which ,makes tire mounting difficult..

It sounds, though, as if you have simply overtightened the valve ring which pinches the valve base
to the rim. No valve ring = no valve ring problems.

In deepest sympathy, Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

"Michael Dart" <[email protected]> wrote in message news:[email protected]...
> Rim tape is pretty much a necessity. Package strapping tape or electrical will work fine as well.

Strapping tape works but electrical will not. It will stretch over the course of a few
weeks and fail.

JT

 

"John Forrest Tomlinson" <[email protected]> wrote in message
news:[email protected]...
> "Michael Dart" <[email protected]> wrote in message
news:[email protected]...
> > Rim tape is pretty much a necessity. Package strapping tape or electrical will work fine
> > as well.
>
> Strapping tape works but electrical will not. It will stretch over the course of a few weeks
> and fail.
>
> JT

Sorry, I forgot road tires use higher pressure. I use it on my downhill bike rims but only run 19
psi. in them. It works in that application.

Mike

 

On 29 May 2003 04:06:31 -0700, [email protected] (John Forrest Tomlinson) wrote:

>"Michael Dart" <[email protected]> wrote in message news:[email protected]...
>> Rim tape is pretty much a necessity. Package strapping tape or electrical will work fine as well.
>
>Strapping tape works but electrical will not. It will stretch over the course of a few weeks
>and fail.
>
>JT

if you are using a presta valve in a shraeder (sp) hole without a grommet, the valve base may not be
getting the support it needs to avoid being extruded out the hole. As Alex notes, some valves are
worse than others - Ъ×

 

1st are you using a floor pump if not get one .For fixing flats at home they are worth the few
dollars .It help keeping you from putting to much stress on the valve stem . If you are using a
floor pump then you should try inflating with out the nut on till u get the knack of it . you can
put them pump head on by pushing the tire till it seats . after inflating put nut on. I was having
trouble on my road bike with hand pumps by the time I got enough air in I was pumping like a mad man
not a good thing . just a idea .

--
J/O Trailblazer At large !!

 

> It's not OK. Just be civil and admit who you are. Spammers do not read signature lines so that
> excuse for anonymity doesn't hold.
Ever thought about a person being anon for reasons other than anti-spam? I might be a celebrity
looking to stay out of the spotlight. You never know. If I am not being civil to this NG or any
member of it, I expect to be called on it. I think people should always be civil to each other, if
not, people tend to start deviating from the true topic and start to degrade into attacking each
other personally. That doesn't get anyone anywhere.

> You have a manufacturing defect in the tube, the common stem separation effect that cannot be
> easily fixed. You should take it to your bicycle shop and demand a new one. This has been going on
> for a few years and everyone chastises himself for having done something wrong. It is a faulty
> tube. That's it!
If it's a manuf defect, does it carry from one manuf to another? I bought a Bontrager brand tube.
Regular tube for road bike. Nothing special or anything. Would I have better luck with a diff manuf?

> spoke nipples. It is an essential part of a clincher wheel. It has
What's a clincher wheel? Sheldon Brown's glossary has a "Clincher Tire" listed. This describes my
wheel. I hope that's the same thing.

> You might want to read about patching procedures and how to avoid leaky patches at:
>
> http://draco.acs.uci.edu/rbfaq/FAQ/8b.1.html
I read it. Thanks for taking the time to setup FAQ's like this. It really helps us newbies out! I
didn't read anything in there that exactly pertained to my particular problem though. If it has been
going on for a few years like you said, do you want to include something in your FAQ about this
particular issue? The other patch I did on the tire has held successfully for sometime now, even up
until this cut stem issue.

Thanks again for the GREAT info!

 

Ok, I talked to a friend of mine and she had this same kind of problem for a while. Apparently, her
issue was that her tube had too much play in it when it was in the rim. The LBS replaced the tubes
and looked at the rim, then tried a tube that was a bit more snug than the one she had been using.
My rim, actually the tire says Continental Ultra 2000 (700x23c). The LBS sold me a Bontrager tube
that said for sizes 700x18-25. I'm assuming this is Bontrager's closest sized tube. Should I look
for a diff manuf that has a closer size? This might alleviate Jobst Brandt's issue about it being a
manuf defect.

Any thoughts about this? Thanks in advance.

 

> At any rate, for today dump the valve ring.
It would seem to me that the valve ring should actually be on the INSIDE of the rim. It seems to me
that as the tube gets inflated, the stem gets pressed OUT the hole. If this is the case, shouldn't
the ring be INSIDE the rim to prevent the stem from getting forced out the hole so much? Has anyone
tried this?

> When you inflate the tube, are you careful to press between your hands, cupping the rim/valve with
> one hand so you do not press against the side
of
> the valve stem? ( I am assuming you're using an express pump without a hose. If your pump has a
> hose, none of that is relevant)
As best as I can. I am using a Specialized brand hand pump. I figured I wouldn't need 2 diff types
of pumps to do the same job, but I may rethink this idea.

> If there is some sharp edge inside your rim unprotected by the tape,
correct
> that. Briefly reviewing rim liners, solid-section rims in which the
nipples
> stick up inside the tire channel require a rubber rim liner. Make sure it
is
> skinny enough to stay off the tire bead seat. Cotton tapes in that style rim will cut through from
> the nipple slots when truing. Hollow-section
rims
> which have recesses for the nipples require a polyurethane or cotton cloth liner to prevent the
> tube from herniating into those recesses. Pull the cotton tape tight when you wrap it so it
> doesn't fall into the nipple recesses itself. Ensure the tape covers the entire width of the
> nipple recess without occluding the tire bead seat. (There are several widths available in all
> three materials.) On some rims this is not possible as
the
> holes extend all the way to the edge, in which event you're screwed and
must
> settle for an overly wide tape which ,makes tire mounting difficult..
The rim is a Mavic Open Pro. When I look at it, there is no kind of liner or sleeve that goes
between layers of the rim. There is the tape, but like I said, it is worn away right at the hole
part. This is all that is necessary for this rim correct?

> In deepest sympathy,
LOL!!! Hey, I'll learn. ;-) Thanks again for the advice!

 

After you re-mount the tube and tire, and before you put the collar back on (if you choose to use
it at all) pump up the tire to about 10 to 20 psi. Then, remove the pump and push the valve all the
way in, release it and continue filling. You must be sure that the rubber flange of the valve is
seated above the tire beads, not between the beads and the rim or it will blow off. I think that is
your problem.

Also, it does not hurt to de-burr the inner and outer edge of the valve hole in the rim as many rim
makers neglect to do this.

But I'd guess that either Jobst is correct or I am or both.

Steve Shapiro [email protected]

 

[email protected] wrote:
> Spammers do not read signature lines so that excuse for anonymity doesn't hold.

I'd like to believe you - do you have any evidence for this claim? I get too much junk to accept
this without evidence.

(FWIW, I think this fuss over anonymity is really silly, in both directions.)
--
Mark Janeba remove antispam phrase in address to reply (and no, I won't be putting my email address
here either)

 

In article <[email protected]>, nospam <[email protected]> wrote:
>> At any rate, for today dump the valve ring.
>It would seem to me that the valve ring should actually be on the INSIDE of the rim.

No, don't do this.

> It seems to me that as the tube gets inflated, the stem gets pressed OUT the hole.

The valve should be a close fit in the hole. If it's not, then you have rims drilled for schrader
valves and you need an adapter grommet.

The valve collar is useful for holding the valve in place when there is little or no air in the
tube. Once it's aired up it is no longer needed. You can do without it entirely-- when there is no
air in the tube, you can push the tire in where the valve is to keep the pump head from poking it
inside the tire.

>As best as I can. I am using a Specialized brand hand pump. I figured I wouldn't need 2 diff types
>of pumps to do the same job, but I may rethink this idea.

Get a floor pump. They work a lot better. Some hand pumps tend to stress the valve with sideways
force-- ok for roadside flat fixing but not daily airing up.

>The rim is a Mavic Open Pro. When I look at it, there is no kind of liner or sleeve that goes
>between layers of the rim. There is the tape, but like I said, it is worn away right at the hole
>part. This is all that is necessary for this rim correct?

The rim tape is there to block off the spoke nipple holes. Otherwise the tube protudes into them and
chafes on the edges of the holes and you flat. Pretty quickly I might add.

Make sure the valve hole doesn't have any sharp edges. I have had this problem and used a file on
the hole to smooth it off.

>LOL!!! Hey, I'll learn. ;-) Thanks again for the advice!

BTW, Jobst was baiting you.

Eric

 

> a burr on the rim hole. I remove the stem, that leaves a small hole the size of the stem diameter,
> and insert a stem from a latex tubular and continue using the tube. This type stem is shown at:
>
> http://www.yellowjersey.org/NUVALVE.JPG

Ok, I get the diff valve. It actaully has some substance where it meets the tube. Do you then apply
some form of adhesive to make it stay in place or does the air pressure in the tube keep it there?
If' I go to my LBS, and ask them for a latex tubular stem will they know what I am talking about?

Also, what does the dice have to do with tires/valves/biking? Do you roll it before your ride to
predict if you will get a flat or not? ;-)

 

[email protected]<[email protected]>[email protected]<[email protected]>[email protected]<[email protected]
spam.com>[email protected]<[email protected]>[email protected]<[email protected]>[email protected]<no-
[email protected]>[email protected]<[email protected]>[email protected]<[email protected]>[email protected]
llspam<[email protected]> writes:

>> I remove the stem, that leaves a small hole the size of the stem diameter, and insert a stem from
>> a latex tubular and continue using the tube. This type stem is shown at:

http://www.yellowjersey.org/NUVALVE.JPG

> Ok, I get the diff valve. It actaully has some substance where it meets the tube. Do you then
> apply some form of adhesive to make it stay in place or does the air pressure in the tube keep
> it there? If' I go to my LBS, and ask them for a latex tubular stem will they know what I am
> talking about?

THe tube fits between the mushroom end and the dished washer with the retaining nut screwed down
tightly. THat makes an air seal and holds the stem in place. You still need a knurled nut on the
outside to steady thhe stem for pumping.

Jobst Brandt [email protected] Palo Alto CA

 

"Mark Janeba" <[email protected]> wrote in message news:[email protected]...
> [email protected] wrote:
> > Spammers do not read signature lines so that excuse for anonymity doesn't hold.
>
> I'd like to believe you - do you have any evidence for this claim? I get too much junk to accept
> this without evidence.
>
> (FWIW, I think this fuss over anonymity is really silly, in both directions.)

What he is saying is that spammers are not reading your name, they are just harvesting your address.
So whether you disclose your true identity or write anonymously as Dirk Diggler does not matter so
long as your e-mail address is ripe for the picking.

The more compelling argument is stalkers, but that risk already exists for everyone who discloses
their name in public by whatever means. I find it amusing that some people who post anonymously for
privacy reasons also give out links to their personal web-sites which reveal the most intimate
details of their lives from where they live to the names of their pets and relatives -- with
pictures, no less. -- Jay Beattie.

 

"nospam" <[email protected]> wrote in message news:[email protected]...
> > At any rate, for today dump the valve ring.
> It would seem to me that the valve ring should actually be on the INSIDE
of
> the rim. It seems to me that as the tube gets inflated, the stem gets pressed OUT the hole. If
> this is the case, shouldn't the ring be INSIDE
the
> rim to prevent the stem from getting forced out the hole so much? Has
anyone
> tried this?
>
> > When you inflate the tube, are you careful to press between your hands, cupping the rim/valve
> > with one hand so you do not press against the side
> of
> > the valve stem? ( I am assuming you're using an express pump without a hose. If your pump has a
> > hose, none of that is relevant)
> As best as I can. I am using a Specialized brand hand pump. I figured I wouldn't need 2 diff types
> of pumps to do the same job, but I may rethink this idea.
>
> > If there is some sharp edge inside your rim unprotected by the tape,
> correct
> > that. Briefly reviewing rim liners, solid-section rims in which the
> nipples
> > stick up inside the tire channel require a rubber rim liner. Make sure
it
> is
> > skinny enough to stay off the tire bead seat. Cotton tapes in that
style
> > rim will cut through from the nipple slots when truing. Hollow-section
> rims
> > which have recesses for the nipples require a polyurethane or cotton
cloth
> > liner to prevent the tube from herniating into those recesses. Pull the cotton tape tight when
> > you wrap it so it doesn't fall into the nipple recesses itself. Ensure the tape covers the
> > entire width of the nipple recess without occluding the tire bead seat. (There are several
> > widths available in all three materials.) On some rims this is not possible as
> the
> > holes extend all the way to the edge, in which event you're screwed and
> must
> > settle for an overly wide tape which ,makes tire mounting difficult..
> The rim is a Mavic Open Pro. When I look at it, there is no kind of liner
or
> sleeve that goes between layers of the rim. There is the tape, but like I said, it is worn away
> right at the hole part. This is all that is
necessary
> for this rim correct?
>
> > In deepest sympathy,
> LOL!!! Hey, I'll learn. ;-) Thanks again for the advice!

When you add a valve ring inside the rim, the tube tries to fill the space next to the ring and
distends, sometimes enough to fail. Nothing positive is gained by pushing the base of the valve up
inside the rim ( the effect of adding a valve ring there).

Unless there is sharp edge or an open hole, the rim and rim liner are not the problem. I have read
here before of a defective presta valve as Jobst suggests, one in which the valve assembly is not
properly bonded to the tube. Anyone care to offer a brand where that's been the case? Here, I use
Michelins and Kenda and have not seen that although it seems a plausible explanation.

Did your valve indeed separate from the tube or was there some other failure mode?
--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

 

"[email protected]" <[email protected]> wrote in message news:[email protected]...
> Ok, I talked to a friend of mine and she had this same kind of problem for
a
> while. Apparently, her issue was that her tube had too much play in it when it
was
> in the rim. The LBS replaced the tubes and looked at the rim, then tried a tube that was a bit
> more snug than the one she had been using. My rim, actually the tire says Continental Ultra 2000
> (700x23c). The LBS sold me a Bontrager tube that said for sizes 700x18-25. I'm assuming this is
> Bontrager's closest sized tube. Should I look for a diff manuf that has a closer size? This might
alleviate
> Jobst Brandt's issue about it being a manuf defect.
>
> Any thoughts about this? Thanks in advance.
>
>

Yes, tires and tubes experience "size creep", wherein any given product gets smaller every time it
is retooled. Last summer, I came across a case of vintage 27x1-1/4" IRC tubes from a distributor,
made in 1983. They were significantly larger than our current 700-38 tubes. Thicker, too!

Our current mountain bike tubes for 26x1.95 measure 42mm folded flat in the box. A vintage Carlisle
USA tube new-in-the-box from about 1975 ( I just happen to have one right here) measures 63mm folded
flat in the box. That's only mildly annoying for a fat tire. When you drop 1/3 the width from a
700-23 and take a little off the wall thickness as well you get a tube that's siginificantly more
prone to failure. Note that on the other side of the equation, wholesale prices for tubes have
barely moved in over 25 years. Something had to give.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971