Tubular tire question

[bob prohaska]

Do tubular tires get tighter, or looser, as they're inflated
on a rim? I've never so much as seen one, much less handled
or ridden on one, but I'm curious anyway. Given uniform stretch
in the casing, it seems likely they'd get bigger in all directions.

Is that what motivated the invention of wired-on clinchers?

Thanks for reading, and apologies if I'm overlooking the obvious.

bob prohaska

[AMuzi]

Marginally looser in that the cross section becomes more
round and the seam lays flat. It's a small effect.

Mythical 'tubular pre stretch' as in 'inflate overnight' is
not an actual thing IME. Like 'cable stretch', it's mostly
a misidentified secondary effect unrelated to fabric
structure itself.

Used (ridden) tubulars are as 'seated in' as a used cable
with no actual material stretch in either case.



--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[John B.]

Tubular's are glued onto the rim which is a different shape then that
used for a conventional tire and tube.
https://tinyurl.com/5n6smdzs

While I have never weighed them I "think" a tubular wheel and tire is
probably a bit lighter then a conventional tire and inner tube wheel
and tire.
--
Cheers,

John B.

[funkma...@hotmail.com]

As Andrew notes, they tend to loosen up a bit. Prestretching does help in some cases but as Andrew notes it doesn't happen overnight. You have to leave it inflated for several weeks, but even then unless you're dealing with a natural fiber casing or very cheap man-made fiber casing it's marginal. I have over 30 years experience with continental Sprinter 250s. They only way they seem to be easy to get on and off is by riding them for several seasons. No amount of pre-stretching has any effect whatsoever. I also vividly remember remember an experience with a low-end Michelin sew-up in the 80's. I removed the tire to repair it (yes, I used to repair sew-ups way back when). When I put it back on the rim it was so loose I wasn't comfortable using it.

[Tom Kunich]

I rode tubular road tires for several years when I first started riding because clincher tires were crap. I don't remember much about them than it only taking 5 minutes to pull off of the flatted old tubular, pull on the spare and pump it up. The spares were always pre-used and glued. I can't remember them getting looser on the rims but that was a hell of a long time ago. In 2024 I pulled a crate of tubulars off of the shelf and threw them away. I can't remember what I was doing but there were green knobbies in the crate. So I guess I started racing cyclocross for awhile.

[AMuzi]

On 8/11/2023 8:04 AM, funkma...@hotmail.com wrote:

Michelin Nibbio?
Low thread count casing, much like a Pirelli Gran Premio.

[funkma...@hotmail.com]

I don't recall the model. I do remember it was recommended as a training tire.

[Frank Krygowski]

Bob may want to clear this up a bit, but:

ISTM that what Bob's asking is akin to the old questions "If you heat up
a ring or tube made of metal so it expands, will the hole get bigger or
smaller?" Some people think the expanding wall will make the hole
smaller, but it doesn't. Anyone who's ever assembled a shrink fit knows
the hole gets bigger as the metal expands.

And anyone who's purposely over-inflated a loose inner tube to find a
tiny leak knows the tube gets bigger everywhere - cross section, outer
diameter, inner diameter.

So _IF_ inflating a tubular tire were analogous to that, it seems
inflating it would make it looser on the rim. It seems the inside
diameter would increase.

But I don't think the analogy works. The tire's fabric is nearly
inextensible. And the base tape is another layer of different material
that greatly restricts its own increase in length. I'd expect that the
inner circumference and inner diameter of the tire would be almost
independent of tire pressure, as would the tightness on the rim.

But I have only a few hours experience with tubular tires, so I'd go
with what Andrew says. Especially since his answer sort of corroborates
mine!

--
- Frank Krygowski

[Tom Kunich]

You didn't say you used tubulars, but you're telling us what they did?

[AMuzi]

On 8/11/2023 3:46 PM, Frank Krygowski wrote:
> On 8/10/2023 10:40 PM, AMuzi wrote:
>> On 8/10/2023 9:16 PM, bob prohaska wrote:
>>> Do tubular tires get tighter, or looser, as they're inflated
>>> on a rim? I've never so much as seen one, much less handled
>>> or ridden on one, but I'm curious anyway. Given uniform
>>> stretch
>>> in the casing, it seems likely they'd get bigger in all
>>> directions.
>>>
>>> Is that what motivated the invention of wired-on clinchers?
>>>
>>> Thanks for reading, and apologies if I'm overlooking the
>>> obvious.
>>>
>>> bob prohaska
>>>
>>
>> Marginally looser in that the cross section becomes more
>> round and the seam lays flat. It's a small effect.
>>
>> Mythical 'tubular pre stretch' as in 'inflate overnight'

>> is not an actual thing IME. Like 'cable stretch', it'sÂ

Yes nice explanation.
Further, as Jobst noted regularly, the bias cut of the
fabric makes a tubular tighter on the rim inflated than when
not.

[Tom Kunich]

I would like to know why they would make tubular rims on which the tire would loosen up and the only thing holding it on the rim would be glue. The underside of a tubular is cloth whereas the upper side is hard rubber. The tire is FORCED to tighten on the rim upon inflation.

[Catrike Rider]

So is the tubular tire tighter on the rim when inflated, or loser?

[AMuzi]

Under pressure a tubular fits tightly on the rim. This is
readily observed.

Our [RBT} FAQ from Mr Brandt himself:

http://www.faqs.org/faqs/bicycles-faq/part3/

See the penultimate paragraph of section 8b.19 (or the whole
section - reading Brandt generally is a joy)

[Catrike Rider]

On Fri, 11 Aug 2023 16:57:54 -0500, AMuzi <a...@yellowjersey.org> wrote:

>On 8/11/2023 4:26 PM, Catrike Rider wrote:
>> On Fri, 11 Aug 2023 16:12:37 -0500, AMuzi <a...@yellowjersey.org> wrote:
>>
>>> On 8/11/2023 3:46 PM, Frank Krygowski wrote:
>>>> On 8/10/2023 10:40 PM, AMuzi wrote:
>>>>> On 8/10/2023 9:16 PM, bob prohaska wrote:
>>>>>> Do tubular tires get tighter, or looser, as they're inflated
>>>>>> on a rim? I've never so much as seen one, much less handled
>>>>>> or ridden on one, but I'm curious anyway. Given uniform
>>>>>> stretch
>>>>>> in the casing, it seems likely they'd get bigger in all
>>>>>> directions.
>>>>>>
>>>>>> Is that what motivated the invention of wired-on clinchers?
>>>>>>
>>>>>> Thanks for reading, and apologies if I'm overlooking the
>>>>>> obvious.
>>>>>>
>>>>>> bob prohaska
>>>>>>
>>>>>
>>>>> Marginally looser in that the cross section becomes more
>>>>> round and the seam lays flat. It's a small effect.
>>>>>
>>>>> Mythical 'tubular pre stretch' as in 'inflate overnight'

>>>>> is not an actual thing IME. Like 'cable stretch', it'sĀ

I read a good deal of that. Very interesting. I'd heard the term
"tubular" many times, but never looked it up, so I was totally
ignorant about them.

As for me, one of my primary concerns is to prevent a flat tire. My
choice in tires reflects that, given that I have to guide three wheel
tracks through debri, rather than just one.

I was a bit curious about the changing a tubular faster than a
clincher, thing, but no, I'll never be building a tubular wheel for my
Catrike. The lateral force the trycle exerts on the tire is very
different from a two wheeler. It appears to be the same kind of force
one uses to remove the tubular from the rim.

[bob prohaska]

Frank Krygowski <frkr...@sbcglobal.net> wrote:
>
> And anyone who's purposely over-inflated a loose inner tube to find a
> tiny leak knows the tube gets bigger everywhere - cross section, outer
> diameter, inner diameter.
>
> So _IF_ inflating a tubular tire were analogous to that, it seems
> inflating it would make it looser on the rim. It seems the inside
> diameter would increase.
>
> But I don't think the analogy works. The tire's fabric is nearly
> inextensible.

Key here being "nearly".

> And the base tape is another layer of different material
> that greatly restricts its own increase in length. I'd expect that the
> inner circumference and inner diameter of the tire would be almost
> independent of tire pressure, as would the tightness on the rim.

If I'm understanding the replies so far it's up to the tire
builder to set the ply angle in a way that makes the major
and minor circumferences expand to keep the tire fitted to
the rim. Presumably one wants a little less growth in the
major circumference and a little more growth in the minor.

It sounds like the base tape would thus see a little compression,
which it can't control and would result in wrinkles if excessive.
That leaves me wondering what the base tape's job is.

Thanks to all who've replied!

bob prohaska

[John B.]

On Fri, 11 Aug 2023 16:12:37 -0500, AMuzi <a...@yellowjersey.org> wrote:

Way back when I first started using tubulars, knowing very little
about them and worried that the glue might not hold them securely, I
mounted a new clean tire on a clean rim with no glue and inflated
it... Yup! the inflated tire IS tight on the wheel :-)

--
Cheers,

John B.

[Frank Krygowski]

That's an interesting point about the bias and its clamping effect.
It makes sense.

- Frank Krygowski

[Frank Krygowski]

On Friday, August 11, 2023 at 5:59:09 PM UTC-4, AMuzi wrote:
>
> Our [RBT} FAQ from Mr Brandt himself:
>
> http://www.faqs.org/faqs/bicycles-faq/part3/
>
> See the penultimate paragraph of section 8b.19 (or the whole
> section - reading Brandt generally is a joy)

Agreed! I learned a lot from Jobst.

- Frank Krygowski

[Catrike Rider]

On Sat, 12 Aug 2023 07:37:51 +0700, John B. <sloc...@gmail.com>
wrote:

I still don't see the advantages of using tubular tires, except
perhaps weight. It seems to me that patching one of them out on the
road is a giant pain in the ass compared to patching an innertube, or
simply simply popping a new tube into my clinchers.

[John B.]

You don't "patch" them on the road. You do that at home at your
leisure :-)
You can fold a deflated tubular small enough that you can easily carry
3 under the rear of the seat, tied on with an old toe strap. Certainly
you will have pre-glued the underseaters so if you get a flat you
stop, pop the wheel off, rip off the flat and replace it with one of
the spares, inflate, pop the wheel back on - quick releases of course
- and you are on your way.

--
Cheers,

John B.

[Catrike Rider]

On Sat, 12 Aug 2023 16:21:39 +0700, John B. <sloc...@gmail.com>

Ahhhh, I didn't realize that you could preglue them. Though, correct
me, if I'm wrong, wouldn't the glue make folding and stashing them a
problem? Again, I'm not arguing, just curious, and trying to
understand.

[John B.]

On Sat, 12 Aug 2023 05:37:36 -0400, Catrike Rider

The glue, or at least the glue that I used, never hardened. It was
always "tacky" so the inner portion of the tire had a layer of "sticky
stuff" and when you put it on the wheel which had previously been
coated with "glue", and was sticky, the tire adhered to the wheel but
as the glue never actually hardened you could pull the tire off the
wheel with a little effort. The "spare tires" were pre glued and while
the glued surfaces did stick together as the glue never actually
hardened you could pull them apart with little effort.,
--
Cheers,

John B.

[Catrike Rider]

On Sat, 12 Aug 2023 18:25:05 +0700, John B. <sloc...@gmail.com>

Thanks. Now that I know a little about them, they do not seem as
"awful" as I had originally imagined. I am, however, going to stick to
my big heavy clinchers. I'm pretty quick at changing out a tube, and
although I seldom do it any more, I'm also good at patching a tube out
on a ride.

[AMuzi]

Two different things.

On the road tubular repair would indeed be daunting, likely
more difficult than patching an inner tube in rain or cold.

But as you note a tube replacement is straightforward. As is
a tubular change:
https://biografieonline.it/img/bio/Gino_Bartali_1.jpg

[AMuzi]

Tubular cement is a mastic temperature-dependent solution,
similar to contact cement; not at all like cyanoacrylate
which crystallizes rock-hard.

[Tom Kunich]

Frank, when you so clearly have never used tubulars WHY are you commenting on them? All it would take if for you to put a tubular on its unglued rim and inflate it and feel it for you to know that the tire expands inward and bias has nothing to do with it. For crying out loud - why do you think that they are called "sew-ups"?

[Tom Kunich]

I still have at least one tube of it down in the garage.

[Frank Krygowski]

Hmm. Jobst Brandt says the bias has something definite to do with it.
Andrew Musi seems to agree with Jobst. Visualizing the effect of the
bias fabric during inflation tells me the same thing.

Your claim that "bias has nothing to do with it" seems like your typical
uninformed spouting.

--
- Frank Krygowski

[John B.]

On Sat, 12 Aug 2023 07:44:52 -0400, Catrike Rider

"Horses for courses" as they say.
--
Cheers,

John B.

[John B.]

On Sat, 12 Aug 2023 08:13:31 -0500, AMuzi <a...@yellowjersey.org> wrote:

>On 8/12/2023 3:12 AM, Catrike Rider wrote:
>> On Sat, 12 Aug 2023 07:37:51 +0700, John B. <sloc...@gmail.com>
>> wrote:
>>
>>> On Fri, 11 Aug 2023 16:12:37 -0500, AMuzi <a...@yellowjersey.org> wrote:
>>>
>>>> On 8/11/2023 3:46 PM, Frank Krygowski wrote:
>>>>> On 8/10/2023 10:40 PM, AMuzi wrote:
>>>>>> On 8/10/2023 9:16 PM, bob prohaska wrote:
>>>>>>> Do tubular tires get tighter, or looser, as they're inflated
>>>>>>> on a rim? I've never so much as seen one, much less handled
>>>>>>> or ridden on one, but I'm curious anyway. Given uniform
>>>>>>> stretch
>>>>>>> in the casing, it seems likely they'd get bigger in all
>>>>>>> directions.
>>>>>>>
>>>>>>> Is that what motivated the invention of wired-on clinchers?
>>>>>>>
>>>>>>> Thanks for reading, and apologies if I'm overlooking the
>>>>>>> obvious.
>>>>>>>
>>>>>>> bob prohaska
>>>>>>>
>>>>>>
>>>>>> Marginally looser in that the cross section becomes more
>>>>>> round and the seam lays flat. It's a small effect.
>>>>>>
>>>>>> Mythical 'tubular pre stretch' as in 'inflate overnight'

>>>>>> is not an actual thing IME. Like 'cable stretch', it'sĀ

It's strange. I never thought that carrying spare inner tubes might be
better then "fixing a flat" nor have I ever seen anyone doing such a
thing. But when you think about it does seem a logical thing to do.

Rather then the alternate, to be setting in the mud on the side of the
road trying to get a patch to stick to a wet tube when it is
thundering down rain :-(

--
Cheers,

John B.

[Catrike Rider]

On Sun, 13 Aug 2023 05:54:58 +0700, John B. <sloc...@gmail.com>

Once I found the leak, slapping on a patch was a snap.

[Sir Ridesalot]

The base tape covers and thereby protects the stitching of the tire casing, and also serves as the surface you apply the cement to in order to mount the tire securely.

Cheers

[funkma...@hotmail.com]

They're called sew-ups because of the construction technique, you idiot. It has nothing to do with mounting the tire.

[Tom Kunich]

The base tape is glued onto the stitching and the stitching EXPANDS downwards as it takes up the slack in the stitches. Since you raced I assume that you put unglued sewups on a tubular rim and pumped them up to "expand" them? Did you ever find a tubular getting looser on the rim? That is what triggered that discussion.

Did you ever repair a sewup by pulling the base tape free, cutting the threads on the sewup, pulling the leaky tube out enough to patch it and then putting everything back the way it was?

I don't have the slightest idea where some of these discussions come from - outer space it seems. Or the work of the Devil.

[funkma...@hotmail.com]

On Sunday, August 13, 2023 at 6:07:14 PM UTC-4, Tom Kunich wrote:
> On Sunday, August 13, 2023 at 6:26:13 AM UTC-7, funkma...@hotmail.com wrote:
> >
> > > Frank, when you so clearly have never used tubulars WHY are you commenting on them? All it would take if for you to put a tubular on its unglued rim and inflate it and feel it for you to know that the tire expands inward and bias has nothing to do with it. For crying out loud - why do you think that they are called "sew-ups"?
> >
> > They're called sew-ups because of the construction technique, you idiot. It has nothing to do with mounting the tire.
>
> The base tape is glued onto the stitching and the stitching EXPANDS downwards as it takes up the slack in the stitches.

And the reason they're called sew-ups is because they are sewn together, not because of the way they are mounted.
https://www.sheldonbrown.com/gloss_tp-z.html#tubular
"A tubular tire has no beads; instead, the two edges of the carcass are sewn together (hence the term "sew-up") with the inner tube inside. "

> Since you raced I assume that you put unglued sewups on a tubular rim and pumped them up to "expand" them? Did you ever find a tubular getting looser on the rim? That is what triggered that discussion.

Yes, I noted that above.

> Did you ever repair a sewup by pulling the base tape free, cutting the threads on the sewup, pulling the leaky tube out enough to patch it and then putting everything back the way it was?

Yes, I noted that above as well. I still have my old Velox repair kit in the orange steel box: Needle, thimble, and thread.

> I don't have the slightest idea where some of these discussions come from - outer space it seems. Or the work of the Devil.

They're usually fine until you get involved.

[Tom Kunich]

You stupid idiot, you agreed with Andrew when you had no idea what he meant.

"As Andrew notes, they tend to loosen up a bit. Prestretching does help in some cases but as Andrew notes it doesn't happen overnight. You have to leave it inflated for several weeks, but even then unless you're dealing with a natural fiber casing or very cheap man-made fiber casing it's marginal. I have over 30 years experience with continental Sprinter 250s. They only way they seem to be easy to get on and off is by riding them for several seasons. No amount of pre-stretching has any effect whatsoever. I also vividly remember remember an experience with a low-end Michelin sew-up in the 80's. I removed the tire to repair it (yes, I used to repair sew-ups way back when). When I put it back on the rim it was so loose I wasn't comfortable using it."

He was talking about the installation of the tire on the rim and you like the idiot with everything you do meant that the tire EXPANDS outward when you inflate it making it looser on the rim.

It's one thing when you're commenting about things you're familiar with but that seems to be getting more and more rare with you.

When you inflate a tubular on a rim it gets tighter on the rim. The glue keeps the tire from rotating on the rim and tearing the filler out. I suppose that it also keeps fatter tires from rolling off of the rim as well since my CX tubulars were 32 mm but I can't recall that. I do remember that the glue would harden and I had a special tool to use to scrap the old glue off of the rim. The Clement glue I have down in the garage doesn't harden all the way if I remember correctly.

Comment all you like but try to stick to things you know something about. Your comments about using a power meter at your age is ridiculous. If you're curious about the changes over time at least be man enough to say so.

[funkma...@hotmail.com]

On Monday, August 14, 2023 at 7:28:12 PM UTC-4, Tom Kunich wrote:
> On Sunday, August 13, 2023 at 5:29:31 PM UTC-7, funkma...@hotmail.com wrote:
> > On Sunday, August 13, 2023 at 6:07:14 PM UTC-4, Tom Kunich wrote:
> > > On Sunday, August 13, 2023 at 6:26:13 AM UTC-7, funkma...@hotmail.com wrote:
> > > >
> > > > > Frank, when you so clearly have never used tubulars WHY are you commenting on them? All it would take if for you to put a tubular on its unglued rim and inflate it and feel it for you to know that the tire expands inward and bias has nothing to do with it. For crying out loud - why do you think that they are called "sew-ups"?
> > > >
> > > > They're called sew-ups because of the construction technique, you idiot. It has nothing to do with mounting the tire.
> > >
> > > The base tape is glued onto the stitching and the stitching EXPANDS downwards as it takes up the slack in the stitches.
> > And the reason they're called sew-ups is because they are sewn together, not because of the way they are mounted.
> > https://www.sheldonbrown.com/gloss_tp-z.html#tubular
> > "A tubular tire has no beads; instead, the two edges of the carcass are sewn together (hence the term "sew-up") with the inner tube inside. "
> > > Since you raced I assume that you put unglued sewups on a tubular rim and pumped them up to "expand" them? Did you ever find a tubular getting looser on the rim? That is what triggered that discussion.
> > Yes, I noted that above.
> > > Did you ever repair a sewup by pulling the base tape free, cutting the threads on the sewup, pulling the leaky tube out enough to patch it and then putting everything back the way it was?
> > Yes, I noted that above as well. I still have my old Velox repair kit in the orange steel box: Needle, thimble, and thread.
> > > I don't have the slightest idea where some of these discussions come from - outer space it seems. Or the work of the Devil.
> > They're usually fine until you get involved.
> You stupid idiot, you agreed with Andrew when you had no idea what he meant.
>
> "As Andrew notes, they tend to loosen up a bit. Prestretching does help in some cases but as Andrew notes it doesn't happen overnight. You have to leave it inflated for several weeks, but even then unless you're dealing with a natural fiber casing or very cheap man-made fiber casing it's marginal. I have over 30 years experience with continental Sprinter 250s. They only way they seem to be easy to get on and off is by riding them for several seasons. No amount of pre-stretching has any effect whatsoever. I also vividly remember remember an experience with a low-end Michelin sew-up in the 80's. I removed the tire to repair it (yes, I used to repair sew-ups way back when). When I put it back on the rim it was so loose I wasn't comfortable using it."
>
> He was talking about the installation of the tire on the rim and you like the idiot with everything you do meant that the tire EXPANDS outward when you inflate it making it looser on the rim.

No, that's not what I wrote. Try some reading comprehension. The question was 'do tubulars loosen up when mounted?" the answer from andrew and me was 'yes, but not much'. I related an anecdote with a cheap tire that actually loosened up quite a bit because it stretched over time- FWIW, Andrew didn't call me out for being wrong (like he does often with you) he asked what brand an model of tire it was. I suspect he's experienced this as well.

Dip shit, the contest here was your question "why do you think that they are called "sew-ups"?

IT's because of the way they are built, not because of the way they are mounted. Who's word on cycling expertise do you think we're going to take, Sheldon brown ("A tubular tire has no beads; instead, the two edges of the carcass are sewn together (hence the term "sew-up") with the inner tube inside. " or you, who can't build a bike without something falling off?

> It's one thing when you're commenting about things you're familiar with but that seems to be getting more and more rare with you.

I've been racing on sew-ups for nearly 40 years. I probably know more about sew-up mounting, remounting and repair than any one here with the possible exception of Andrew.

>
> When you inflate a tubular on a rim it gets tighter on the rim. The glue keeps the tire from rotating on the rim and tearing the filler out. I suppose that it also keeps fatter tires from rolling off of the rim as well since my CX tubulars were 32 mm but I can't recall that. I do remember that the glue would harden and I had a special tool to use to scrap the old glue off of the rim. The Clement glue I have down in the garage doesn't harden all the way if I remember correctly.

None of which has anything to do with why they are called sew-up, idiot.

>
> Comment all you like but try to stick to things you know something about.

I have three wheelsets with sew-ups installed - A older set of Zipp 303's with Tufo Elites, a set of Zipp 303 Firecrest with Tufo Chicanes for Cx, and a Mavic Rear Disc with a Continental Sprinter 250
You have an old tube of glue lying around in the basement somewhere.....take your own advice jackass....

> Your comments about using a power meter at your age is ridiculous. If you're curious about the changes over time at least be man enough to say so.

I use it to train to stay competitive. There is a sizable group of riders up here all in our 50's and 60's who have been racing together for well over 20 years....I've been lining up with a few of them since the early 90's. We all have training programs and use powermeters. Just because you were never able to handle a corner at more than 15 mph with any rider closer the ten feet doesn't mean no one else here has any racing experience.

You're a loudmouth arrogant old asshole who's wrong 90% of the time on every subject. How about you be a man and admit you're wrong.

[Tom Kunich]

You know more than anyone here about sewups and yet agreed that they got looser on the rims when inflated. If that is your sort of knowledge you can keep it. The very fact that they ARE sewn together makes the idea that they expand on both the inside and outside diameter nothing more than someone's wild eyed theory.

But I'm sure that you can still think that the looser end of the tires do not expand outwards which is a reduction of inside diameter. I'm still waiting for your explanation of why an inflated tubular gets tighter on the rim and not looser.

[funkma...@hotmail.com]

For the Second time, you idiot, that is _not_ what I wrote.

> If that is your sort of knowledge you can keep it.

IT only reveals your dismal reading comprehension.

> The very fact that they ARE sewn together makes the idea that they expand on both the inside and outside diameter nothing more than someone's wild eyed theory.

No one wrote that.

> But I'm sure that you can still think that the looser end of the tires do not expand outwards which is a reduction of inside diameter. I'm still waiting for your explanation of why an inflated tubular gets tighter on the rim and not looser.

The mechanism was already aptly explained by Frank and agreed with by Andrew, who further linked to Jobst's explanation. I'm not contradicting any of it. The only person seeming to have an issue with it is you.

And none of this has anything to do with why it's called a sew-up:

[bob prohaska]

Sir Ridesalot <i_am_cyc...@yahoo.ca> wrote:
>
> The base tape covers and thereby protects the stitching of the tire casing, and also serves as the surface you apply the cement to in order to mount the tire securely.
>

I'm having trouble visualizing the setup. The tire casing needs one
seam to close it, leaving two flaps of fabric. Are those each sewn
to the base tape? Is there glue between base tape and casing, or
only between base tape and rim?

I looked for a good illustration and didn't find one, if somebody
has better luck please post a link!

Thanks very much,

bob prohaska

[John B.]

https://www.challengetires.com/technology
https://www.youtube.com/watch?v=BuosST7TiZE

Forget the fact that it is a circle and think of wrapping your
handkerchief around a broomstick. Where the edges meet sew them
together. You now have a tube. To protect your stitches glue a strip
of fabric lengthwise along the tube to cover the stitches.


--
Cheers,

John B.

[funkma...@hotmail.com]

On Thursday, August 17, 2023 at 12:20:26 AM UTC-4, bob prohaska wrote:
> Sir Ridesalot <i_am_cyc...@yahoo.ca> wrote:
> >
> > The base tape covers and thereby protects the stitching of the tire casing, and also serves as the surface you apply the cement to in order to mount the tire securely.
> >
> I'm having trouble visualizing the setup. The tire casing needs one
> seam to close it, leaving two flaps of fabric. Are those each sewn
> to the base tape?

No, they are stitched together, think about what a surgeon would do when he closes you after surgery.

>Is there glue between base tape and casing, or
> only between base tape and rim?

After the seam is sewn shut, the tape is applied over the stitching with glue (mastik) at the factory. That ends up being the tire you buy. When you're ready to mount the tire, you apply a layer of glue to each surface, let it cure to become tacky, then apply another layer to each surface, then mount the tire.

Another solution is rim tape, double-sided adhesive that is used in place of the second glue application. Long ago this wasn't considered reliable, these days the technology has advanced such that it's the more common method. It's the way most CX racers I know (including me) mount tires on their CX rigs.

[AMuzi]

Tubulars are a bias-cut tubular strip of fabric sewn at the
rim side. The casing is coated with latex which is also
used to adhere the tread. Latex solution also adheres the
base tape. Some photos here:

http://www.yellowjersey.org/frontwheel.html
and here:
http://www.yellowjersey.org/tubfix.html

Nice drawings of cross section:
https://www.velo-pages.com/main.php?g2_itemId=40539

Le Cycle had a very nice photo series of a visit to the
Dourdoigne factory in 1976 (?) but it seems to have escaped
the Inter Webs

[Tom Kunich]

You know, I never glued a tubular on like that but I must have. My tubular glue was black mastic sort of stuff. After installing the tubular you had to inflate the tire and let it sit overnight.

[AMuzi]

Hmmm I never say black tubular cement. White, red, brown,
amber but not black. Who made that?

[bob prohaska]

John B. <sloc...@gmail.com> wrote:
> https://www.challengetires.com/technology
> https://www.youtube.com/watch?v=BuosST7TiZE
>
> Forget the fact that it is a circle and think of wrapping your
> handkerchief around a broomstick. Where the edges meet sew them
> together. You now have a tube. To protect your stitches glue a strip
> of fabric lengthwise along the tube to cover the stitches.

I've watched the video twice now, with limited comprehension 8-(

It seems like there are a total of five layers stiched together:
Two edges of two casing plies makes four, plus an intermediate
strip. It isn't clear to me if the intermediate strip is a loaded
member (resisting inflation pressure) or just a cover. Then one
more strip of fabric is added, with glue only, between casing and
rim mounting surface.

Thanks to everybody who has responded to my questions! I've been
trying for some time now to understand the chain of reasoning that
led to the invention of practical pneumatic tires. They've been
a world-changing development, likely on par with railroads. There
remain some weak links in the chain, but fewer now.

bob prohaska

[AMuzi]

The original Dr Dunlop tubular was substantially like the
tires I rode this morning. His were wider and heavier but
same basic design.