Tire-Making - Misguided Ramblings and A Thought Experiment You CanVote On

Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is thin and evenly
applied) do typical bicycle tires all inflate to perfect circular cross
sections, where they are free of the rim edges?


Consider a theoretical clincher tire that is a radial, with the threads
crossing perpendicular to the tire. Each thread (which makes a complete
crossing of the tire casing) cuts a perfect circle around the tube, as
that would be the shortest path. And there are no other threads in other
directions to redistribute stresses, so a radial clincher will inflate
to a 'perfect' circular cross-section.


Now consider a typical bias-ply bicycle clincher, with the bias set at
45°. The threads are perpendicular to each other so it will resist
inflation pressure equally in circumference as well as laterally--but
the path that any single thread follows is not circular. The thread's
path is a slightly-flattened oval, wider than it is taller.... Is the
tire's cross-section still circular, or is it a
slightly-laterally-flattened oval?


Now.... consider a bicycle tire that has a casing with a bias WAY more
than 45°..... say, 75°. The threads are no longer perpendicular to each
other, and are very resistant to circumferential stress, but not lateral
stress. Will this tire inflate to a circular cross-section, or an oval?



Cast your votes

eyeyyehahahha no way Dude ! tires inflate to rim form.

On 11/10/2012 6:13 PM, datakoll wrote:
eyeyyehahahha no way Dude ! tires inflate to rim form.

???

I said cross-section, like this-
http://en.wikipedia.org/wiki/File:Se...bicicletta.svg
-and not including the tire beads. All the casing/tire that is not
touching the beads.

In such diagrams the inflated tire is always drawn circular but I
suspect it is not really, except with a radial tire. And that could
possibly be a good thing....

On Nov 9, 11:24*am, Doug Cimperman wrote:
Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is thin and evenly
applied) do typical bicycle tires all inflate to perfect circular cross
sections, where they are free of the rim edges?

Consider a theoretical clincher tire that is a radial, with the threads
crossing perpendicular to the tire. Each thread (which makes a complete
crossing of the tire casing) cuts a perfect circle around the tube, as
that would be the shortest path. And there are no other threads in other
directions to redistribute stresses, so a radial clincher will inflate
to a 'perfect' circular cross-section.

Now consider a typical bias-ply bicycle clincher, with the bias set at
45 . The threads are perpendicular to each other so it will resist
inflation pressure equally in circumference as well as laterally--but
the path that any single thread follows is not circular. The thread's
path is a slightly-flattened oval, wider than it is taller.... Is the
tire's cross-section still circular, tr is it a
slightly-laterally-flattened oval?

Now.... consider a bicycle tire that has a casing with a bias WAY more
than 45 ..... say, 75 . The threads are no longer perpendicular to each
other, and are very resistant to circumferential stress, but not lateral
stress. Will this tire inflate to a circular cross-section, or an oval?

Cast your votes

To add a point of observation, in a radial casing with (theoretically)
non-elastic circumferential threads, the cross section _could_ be
flattened by constraint of the tire's circumference by the those
threads. Like adding an additional set of "beads" in the center of the
tread. But I don't envision that happening with threads running bead-
to-bead even with a very large longitudinal component.

In others words, I vote circular.
DR
Has your experimentation provided an insight into the has

On 11/11/2012 8:25 AM, DirtRoadie wrote:
On Nov 9, 11:24 am, Doug Cimperman wrote:
Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is thin and evenly
applied) do typical bicycle tires all inflate to perfect circular cross
sections, where they are free of the rim edges?

Consider a theoretical clincher tire that is a radial, with the threads
crossing perpendicular to the tire. Each thread (which makes a complete
crossing of the tire casing) cuts a perfect circle around the tube, as
that would be the shortest path. And there are no other threads in other
directions to redistribute stresses, so a radial clincher will inflate
to a 'perfect' circular cross-section.

Now consider a typical bias-ply bicycle clincher, with the bias set at
45 . The threads are perpendicular to each other so it will resist
inflation pressure equally in circumference as well as laterally--but
the path that any single thread follows is not circular. The thread's
path is a slightly-flattened oval, wider than it is taller.... Is the
tire's cross-section still circular, tr is it a
slightly-laterally-flattened oval?

Now.... consider a bicycle tire that has a casing with a bias WAY more
than 45 ..... say, 75 . The threads are no longer perpendicular to each
other, and are very resistant to circumferential stress, but not lateral
stress. Will this tire inflate to a circular cross-section, or an oval?

Cast your votes

To add a point of observation, in a radial casing with (theoretically)
non-elastic circumferential threads, the cross section _could_ be
flattened by constraint of the tire's circumference by the those
threads. Like adding an additional set of "beads" in the center of the
tread. But I don't envision that happening with threads running bead-
to-bead even with a very large longitudinal component.

In others words, I vote circular.
DR
Has your experimentation provided an insight into the has


Your post is interrupted? ....

On Nov 11, 12:12*pm, Doug Cimperman wrote:
On 11/11/2012 8:25 AM, DirtRoadie wrote:









On Nov 9, 11:24 am, Doug Cimperman wrote:
Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is thin and evenly
applied) do typical bicycle tires all inflate to perfect circular cross
sections, where they are free of the rim edges?

Consider a theoretical clincher tire that is a radial, with the threads
crossing perpendicular to the tire. Each thread (which makes a complete
crossing of the tire casing) cuts a perfect circle around the tube, as
that would be the shortest path. And there are no other threads in other
directions to redistribute stresses, so a radial clincher will inflate
to a 'perfect' circular cross-section.

Now consider a typical bias-ply bicycle clincher, with the bias set at
45 . The threads are perpendicular to each other so it will resist
inflation pressure equally in circumference as well as laterally--but
the path that any single thread follows is not circular. The thread's
path is a slightly-flattened oval, wider than it is taller.... Is the
tire's cross-section still circular, tr is it a
slightly-laterally-flattened oval?

Now.... consider a bicycle tire that has a casing with a bias WAY more
than 45 ..... say, 75 . The threads are no longer perpendicular to each
other, and are very resistant to circumferential stress, but not lateral
stress. Will this tire inflate to a circular cross-section, or an oval?

Cast your votes

To add a point of observation, in a radial casing with (theoretically)
non-elastic circumferential threads, the cross section _could_ be
flattened by constraint of the tire's circumference by the those
threads. Like adding an additional set of "beads" in the center of the
tread. But I don't envision that happening with threads running bead-
to-bead even with a very large longitudinal component.

In others words, I vote circular.
DR
Has *your experimentation provided an insight into the has

Your post is interrupted? ....

Oops. I had intended to delete that.
What I was thinking about was the necessary "scissoring" action of
crossed plies. Or so it would seem.
Envisioning a casing that can be laid flat (a typical "folding" tire)
yet is able to assume an essentially toroidal shape when inflated.
For the flat casing all longitudinal lengths are equal and are the
same as the bead length. But in the inflated tire, any one of those
lengths becomes a circumferential measurement which varies from the
shortest - the length of the bead, to the longest - the center of the
tread.
DR

On 11/11/2012 2:09 PM, DirtRoadie wrote:
On Nov 11, 12:12 pm, Doug Cimperman wrote:
On 11/11/2012 8:25 AM, DirtRoadie wrote:









On Nov 9, 11:24 am, Doug Cimperman wrote:
Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is thin and evenly
applied) do typical bicycle tires all inflate to perfect circular cross
sections, where they are free of the rim edges?

Consider a theoretical clincher tire that is a radial, with the threads
crossing perpendicular to the tire. Each thread (which makes a complete
crossing of the tire casing) cuts a perfect circle around the tube, as
that would be the shortest path. And there are no other threads in other
directions to redistribute stresses, so a radial clincher will inflate
to a 'perfect' circular cross-section.

Now consider a typical bias-ply bicycle clincher, with the bias set at
45 . The threads are perpendicular to each other so it will resist
inflation pressure equally in circumference as well as laterally--but
the path that any single thread follows is not circular. The thread's
path is a slightly-flattened oval, wider than it is taller.... Is the
tire's cross-section still circular, tr is it a
slightly-laterally-flattened oval?

Now.... consider a bicycle tire that has a casing with a bias WAY more
than 45 ..... say, 75 . The threads are no longer perpendicular to each
other, and are very resistant to circumferential stress, but not lateral
stress. Will this tire inflate to a circular cross-section, or an oval?

Cast your votes

To add a point of observation, in a radial casing with (theoretically)
non-elastic circumferential threads, the cross section _could_ be
flattened by constraint of the tire's circumference by the those
threads. Like adding an additional set of "beads" in the center of the
tread. But I don't envision that happening with threads running bead-
to-bead even with a very large longitudinal component.

In others words, I vote circular.
DR
Has your experimentation provided an insight into the has

Your post is interrupted? ....

Oops. I had intended to delete that.
What I was thinking about was the necessary "scissoring" action of
crossed plies. Or so it would seem.
Envisioning a casing that can be laid flat (a typical "folding" tire)
yet is able to assume an essentially toroidal shape when inflated.
For the flat casing all longitudinal lengths are equal and are the
same as the bead length. But in the inflated tire, any one of those
lengths becomes a circumferential measurement which varies from the
shortest - the length of the bead, to the longest - the center of the
tread.
DR


The threads' spacing does increase towards the centerline of the
(inflated) tire, compared to at the bead. This spreading effect is why
woven fabrics cannot be used. They are either woven too tight (too much
friction) to allow this, or they are bonded where there threads cross
(fabrics like leno mesh).


Vintage clincher tires (~100 years ago) were made from flat woven cotton
fabric. I haven't seen it explained what happened to the fabric when
they achieved their final shapes.... The fabric may have been woven
loose to begin with, or maybe the threads just partially
stretched/failed during the final molding stage of manufacturing and
inflation pressures had to be kept low enough not to break what was
left...?

'Cord' tires were universally agreed upon to be a great improvement, and
cord tires were made by hand-winding twine around a former that was
(roughly) in the shape of the desired finished tire. It could well be
that the reason cord tires were more durable was that they didn't start
life with a damaged casing.

On 11/11/2012 3:45 PM, Doug Cimperman wrote:
On 11/11/2012 2:09 PM, DirtRoadie wrote:
On Nov 11, 12:12 pm, Doug Cimperman
wrote:
On 11/11/2012 8:25 AM, DirtRoadie wrote:









On Nov 9, 11:24 am, Doug Cimperman
wrote:
Concerning radials, bias-ply tires and What Lies Beyond
------

The fundamental question here is (assuming the tread is
thin and evenly
applied) do typical bicycle tires all inflate to
perfect circular cross
sections, where they are free of the rim edges?

Consider a theoretical clincher tire that is a radial,
with the threads
crossing perpendicular to the tire. Each thread (which
makes a complete
crossing of the tire casing) cuts a perfect circle
around the tube, as
that would be the shortest path. And there are no other
threads in other
directions to redistribute stresses, so a radial
clincher will inflate
to a 'perfect' circular cross-section.

Now consider a typical bias-ply bicycle clincher, with
the bias set at
45 . The threads are perpendicular to each other so it
will resist
inflation pressure equally in circumference as well as
laterally--but
the path that any single thread follows is not
circular. The thread's
path is a slightly-flattened oval, wider than it is
taller.... Is the
tire's cross-section still circular, tr is it a
slightly-laterally-flattened oval?

Now.... consider a bicycle tire that has a casing with
a bias WAY more
than 45 ..... say, 75 . The threads are no longer
perpendicular to each
other, and are very resistant to circumferential
stress, but not lateral
stress. Will this tire inflate to a circular
cross-section, or an oval?

Cast your votes

To add a point of observation, in a radial casing with
(theoretically)
non-elastic circumferential threads, the cross section
_could_ be
flattened by constraint of the tire's circumference by
the those
threads. Like adding an additional set of "beads" in the
center of the
tread. But I don't envision that happening with threads
running bead-
to-bead even with a very large longitudinal component.

In others words, I vote circular.
DR
Has your experimentation provided an insight into the has

Your post is interrupted? ....

Oops. I had intended to delete that.
What I was thinking about was the necessary "scissoring"
action of
crossed plies. Or so it would seem.
Envisioning a casing that can be laid flat (a typical
"folding" tire)
yet is able to assume an essentially toroidal shape when
inflated.
For the flat casing all longitudinal lengths are equal and
are the
same as the bead length. But in the inflated tire, any one
of those
lengths becomes a circumferential measurement which varies
from the
shortest - the length of the bead, to the longest - the
center of the
tread.
DR


The threads' spacing does increase towards the centerline of
the (inflated) tire, compared to at the bead. This spreading
effect is why woven fabrics cannot be used. They are either
woven too tight (too much friction) to allow this, or they
are bonded where there threads cross (fabrics like leno mesh).


Vintage clincher tires (~100 years ago) were made from flat
woven cotton fabric. I haven't seen it explained what
happened to the fabric when they achieved their final
shapes.... The fabric may have been woven loose to begin
with, or maybe the threads just partially stretched/failed
during the final molding stage of manufacturing and
inflation pressures had to be kept low enough not to break
what was left...?

'Cord' tires were universally agreed upon to be a great
improvement, and cord tires were made by hand-winding twine
around a former that was (roughly) in the shape of the
desired finished tire. It could well be that the reason cord
tires were more durable was that they didn't start life with
a damaged casing.

If I recall, wasn't the Michelin HiLite Comp a woven fabric?
All time great tire BTW.

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

All time great tire BTW.

an understatement....outstanding grip in the rain....precision control feel...and off course,,,woven.

On Friday, November 9, 2012 12:24:56 PM UTC-6, Doug Cimperman wrote:
Concerning radials, bias-ply tires and What Lies Beyond
.....

I did try this, but not very well. I rushed it and made a bunch of pretty sad mistakes. I did get a casing that has (roughly) 60-degree bias threads though. The result when I inflated it onto a rim was that it turned out as round as the radial inflates to.

I may make one more attempt at this in the future; the result doesn't follow what information I had. The casing was VERY poorly made, and I could only put about 10 PSI in it and that may be part of the (observed) problem.

-------

On a related note, Charter is discontinuing their newsgroup service. :\ They said it would shut down November 30, but they seem to have accidentally pulled the plug a couple weeks or so early, which is why I am posting from Google.

What (fee-based) newsgroup services are there that allow filtering by posters? I am not greatly fond of the Google interface and if I gotta pay for something, I don't ever want to see certain posters again....