faster casing = faster tires?!@

bfd said:

So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

Casing thread count, casing material, number of plies on sidewall and
under tread, and the presence and thickness of a rubber layer on the
sidewall are all relevant.

Compare this fast tyre
http://www.veloflex.it/products_tyres_details.htm

with this slow one
http://www.conti-online.com/generator/www/de/en/continental/bicycle/themes/tires/race/grand_prix_4_season/grand_prix_4_season_en.html

As you can see, the Conti has many extra directory layers in the
URI... :-)

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

In article <[email hidden]>,

bfd said:

According to Jan Heine, Vintage Bicycle Quarterly (VBQ) publisher and
French Constructeur AND 650B advocate, his testing found:

"that slow casings make tires slow, and fast casings make tires fast.
This is much more important than diameter or width.

Yes, wider tires are faster, but...

- many wide tires use slow casings. If they were narrower, they'd be
even slower!

- any narrow racing tires use fast casings, so they are faster than
the wide tires. If they were wider, they would be even faster!

The Grand Bois tires have shown that you can make wide tires with
fast casings. It's just that few people have known how (or have
bothered to do it) until recently."

It should also be noted that the now discontinued 584x38 Misuboshi
Trimline, the choice tire of 650B advocates, was also suppose to be
build around *fast* casings. In contrast, the often criticized, but
available 684x38 Panaracer Col de Vie is build around "slow" casing
and rides like it.

I ride on Avocet Road 700x25 tires pumped up to around 85-90psi. They
feel *fast* and are very comfortable. So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

Well, Jan's article raised a lot of discussion, mainly about the quality
of the data, but there were some things that I think are well-agreed
upon. First is that rolling resistance is due to hysteresis - the
energy lost in the flexing of the tire as it rolls through the contact
patch. The less energy this flexing absorbs, the lower the rolling
resistance.

All other things being equal, more supple casing and more flexible
rubber are two ways to lower rolling resistance. Using finer gauge
threads in the casing (127 threads per inch versus 66, for example)
should result in a more supple casing with less rolling resistance. A
thinner rubber tread and thinner rubber on the sidewalls results in less
energy being absorbed in flexing. Different rubber compounds can also
affect this, such as rubber with carbon black or silica. The inner tube
is also an issue. Tread patterns also increase rolling resistance.

Think about the days of high performance silk tubulars such as the
Criterium Seta- a very thin latex tube, a very thin and supple casing,
and a very thin rubber tread with a slight decorative pattern that wore
off in a few miles.

Basically at this time, the consumer is presented with a choice between
skinny high performance tires with supple casings and thin treads, or
wider "utility" tires with thick casings and thick rubber treads for
puncture resistance. If you can find the Schwalbe display in a bike
shop with sections of about 12 different tire models, you can see this
quite clearly. Jan wants wide tires with thin supple casings and thin
rubber treads.

There's a "break point" at which the tire is too wide to use a thin
casing made with fine gauge thread due to casing tension. IIRC that is
about 25-28 mm. Tires wider than that need a heavier casing such as a
66 tpi fabric.

So there's more than just casing affecting the rolling resistance of
tires.

Tim McNamara said:

In article <[email hidden]>,

bfd said:

According to Jan Heine, Vintage Bicycle Quarterly (VBQ) publisher and
French Constructeur AND 650B advocate, his testing found:

Quoted message said:

"that slow casings make tires slow, and fast casings make tires fast.
This is much more important than diameter or width.

Quoted message said:

Yes, wider tires are faster, but...

Quoted message said:

- many wide tires use slow casings. If they were narrower, they'd be
even slower!

Quoted message said:

- any narrow racing tires use fast casings, so they are faster than
the wide tires. If they were wider, they would be even faster!

Quoted message said:

The Grand Bois tires have shown that you can make wide tires with
fast casings. It's just that few people have known how (or have
bothered to do it) until recently."

Quoted message said:

It should also be noted that the now discontinued 584x38 Misuboshi
Trimline, the choice tire of 650B advocates, was also suppose to be
build around *fast* casings. In contrast, the often criticized, but
available 684x38 Panaracer Col de Vie is build around "slow" casing
and rides like it.

Quoted message said:

I ride on Avocet Road 700x25 tires pumped up to around 85-90psi. They
feel *fast* and are very comfortable. So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

Well, Jan's article raised a lot of discussion, mainly about the quality
of the data, but there were some things that I think are well-agreed
upon. First is that rolling resistance is due to hysteresis - the
energy lost in the flexing of the tire as it rolls through the contact
patch. The less energy this flexing absorbs, the lower the rolling
resistance.

All other things being equal, more supple casing and more flexible
rubber are two ways to lower rolling resistance. Using finer gauge
threads in the casing (127 threads per inch versus 66, for example)
should result in a more supple casing with less rolling resistance. A
thinner rubber tread and thinner rubber on the sidewalls results in less
energy being absorbed in flexing. Different rubber compounds can also
affect this, such as rubber with carbon black or silica. The inner tube
is also an issue. Tread patterns also increase rolling resistance.

Think about the days of high performance silk tubulars such as the
Criterium Seta- a very thin latex tube, a very thin and supple casing,
and a very thin rubber tread with a slight decorative pattern that wore
off in a few miles.

Basically at this time, the consumer is presented with a choice between
skinny high performance tires with supple casings and thin treads, or
wider "utility" tires with thick casings and thick rubber treads for
puncture resistance. If you can find the Schwalbe display in a bike
shop with sections of about 12 different tire models, you can see this
quite clearly. Jan wants wide tires with thin supple casings and thin
rubber treads.

There's a "break point" at which the tire is too wide to use a thin
casing made with fine gauge thread due to casing tension. IIRC that is
about 25-28 mm. Tires wider than that need a heavier casing such as a
66 tpi fabric.

So there's more than just casing affecting the rolling resistance of
tires.- Hide quoted text -

Thanks. I wonder how much fabric, i.e., tpi, the *fast* Gran Bois or
discontinued Mitsuboshi Trimline have in them?

bfd said:

So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

The "speed" of a tire is a function of the tire's ability to
elastically restore the mechanical energy stored in the process of
distorting it. Any energy that is dissipated into the tire's casing
or tread as heat can't be returned to sustain the forward motion of
the bike.

In the same way as a normal rubber band gets warm if it's repeatedly
stretched and released, the rubber and other resins in a tire sink
energy when they are worked. Tread and casing thickness is usually
singled out as the main culprit in hysteresis loss, but casing
construction that causes a large amount of shearing action between its
layers (as all bias-ply tires do to some extent) can be lossier than
its physical thickness would otherwise indicate. Radial tires for
bicycles (which should by their nature display much less hysteresis
loss than bias-ply) have been brought to market, but their handling
qualities and subjective feel have made them unpopular and
unsuccessful in the marketplace.

The wider or larger in diameter a tire is, the less its tread and
casing are distorted under a given load and pressure, and the less its
hysteresis losses will be (all else equal).

The other form of kinetic energy loss that is inseparable from other
tire losses is the tendency of a hard tire to transmit energy as jolts
to the rider's body. This latter type of loss can easily make a
"fast", low hysteresis tire draggier overall than a "slow", softer
tire. Larger wheels and wider tires help in ths regard as well.

Avocet Fas-Grip tires seem to have all the right stuff from an
efficiency standpoint-- relatively thin, smooth treads with tapered
edges; thin, high thread count casings; time-proven lampblack tread
rubber; and modestly wide sizes available. I have yet to find a tire
that feels more efficient in any given size than Avocet slicks. My
favorite has been the 26 x 1.9" size, which unfortunately is no longer
manufactured.

Chalo

Chalo said:

bfd said:

So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

The "speed" of a tire is a function of the tire's ability to
elastically restore the mechanical energy stored in the process of
distorting it. Any energy that is dissipated into the tire's casing
or tread as heat can't be returned to sustain the forward motion of
the bike.

In the same way as a normal rubber band gets warm if it's repeatedly
stretched and released, the rubber and other resins in a tire sink
energy when they are worked. Tread and casing thickness is usually
singled out as the main culprit in hysteresis loss, but casing
construction that causes a large amount of shearing action between its
layers (as all bias-ply tires do to some extent) can be lossier than
its physical thickness would otherwise indicate. Radial tires for
bicycles (which should by their nature display much less hysteresis
loss than bias-ply) have been brought to market, but their handling
qualities and subjective feel have made them unpopular and
unsuccessful in the marketplace.

The wider or larger in diameter a tire is, the less its tread and
casing are distorted under a given load and pressure, and the less its
hysteresis losses will be (all else equal).

The other form of kinetic energy loss that is inseparable from other
tire losses is the tendency of a hard tire to transmit energy as jolts
to the rider's body. This latter type of loss can easily make a
"fast", low hysteresis tire draggier overall than a "slow", softer
tire. Larger wheels and wider tires help in ths regard as well.

Avocet Fas-Grip tires seem to have all the right stuff from an
efficiency standpoint-- relatively thin, smooth treads with tapered
edges; thin, high thread count casings; time-proven lampblack tread
rubber; and modestly wide sizes available. I have yet to find a tire
that feels more efficient in any given size than Avocet slicks. My
favorite has been the 26 x 1.9" size, which unfortunately is no longer
manufactured.

That's interesting, Avocet still list a Fasgrip City and Fasgrip City
K in 26x1.9, both with 66 tpi too!

http://avocet.com/tirepages/carbon12_specs.html

The main problem with Avocet has always been their screwed up,
antiquated distribution system (or lack thereof). Supposedly, any LBS
should be able to order tires directly from Avocet. Good Luck with
that!

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as the
tread wears off.
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

In article <[email hidden]>,

bfd said:

The main problem with Avocet has always been their screwed up,
antiquated distribution system (or lack thereof). Supposedly, any LBS
should be able to order tires directly from Avocet. Good Luck with
that!

In the past there has been a high minimum order- too high- that had
discouraged bike shops from buying their tires. I don't know if that is
still the case.

In article <[email hidden]>,

John Forrest Tomlinson said:

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as
the tread wears off.

That would make sense. Heine also thought there is a "break-in" period
in which the casing "loosens up," but I have never seen that mentioned
anywhere else.

In article <[email hidden]>,

bfd said:

I wonder how much fabric, i.e., tpi, the *fast* Gran Bois or
discontinued Mitsuboshi Trimline have in them?

No idea.

Quoted message said:

In article <[email hidden]>,

bfd said:

The main problem with Avocet has always been their screwed up,
antiquated distribution system (or lack thereof). Supposedly, any LBS
should be able to order tires directly from Avocet. Good Luck with
that!

Tim McNamara said:

In the past there has been a high minimum order- too high- that had
discouraged bike shops from buying their tires. I don't know if that is
still the case.

I don't recall that as an issue. It may well be.

Our tire vendors ship to arrive the next morning on 4pm orders. Avocet
is not at all convenient in that regard.

Our tire vendors ship tires mixed with daily shipments of other goods -
from Tourney changers to frames to Record Ergos - which are shipping
anyway.

There are other business level factors. With today's huge inventory
levels over relatively static volume I can no longer justify the
commitment. YMMV.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

bfd said:

So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

Put it on a test rig and test it for rolling resistance.

Matt O.

Tim McNamara said:

There's a "break point" at which the tire is too wide to use a thin
casing made with fine gauge thread due to casing tension. IIRC that is
about 25-28 mm. Tires wider than that need a heavier casing such as a
66 tpi fabric.

There may be a technical limitation, but I suspect the "break
point" is determined by the market. Most people who want
fast tires want 23mm ones, whether they should or not. Riders or product
managers who want >25mm tires want durable, cheaper ones.

Also, sizes are only nominal. A 28mm Conti is narrower than a 25mm
Michelin.

Matt O.

bfd said:

Chalo said:

bfd said:

So, the question is how do you
tell whether a tire is build around *fast* casing or "slow" casing?
Or, is this just a myth?

The "speed" of a tire is a function of the tire's ability to
elastically restore the mechanical energy stored in the process of
distorting it. Any energy that is dissipated into the tire's casing
or tread as heat can't be returned to sustain the forward motion of
the bike.

In the same way as a normal rubber band gets warm if it's repeatedly
stretched and released, the rubber and other resins in a tire sink
energy when they are worked. Tread and casing thickness is usually
singled out as the main culprit in hysteresis loss, but casing
construction that causes a large amount of shearing action between its
layers (as all bias-ply tires do to some extent) can be lossier than
its physical thickness would otherwise indicate. Radial tires for
bicycles (which should by their nature display much less hysteresis
loss than bias-ply) have been brought to market, but their handling
qualities and subjective feel have made them unpopular and
unsuccessful in the marketplace.

The wider or larger in diameter a tire is, the less its tread and
casing are distorted under a given load and pressure, and the less its
hysteresis losses will be (all else equal).

The other form of kinetic energy loss that is inseparable from other
tire losses is the tendency of a hard tire to transmit energy as jolts
to the rider's body. This latter type of loss can easily make a
"fast", low hysteresis tire draggier overall than a "slow", softer
tire. Larger wheels and wider tires help in ths regard as well.

Avocet Fas-Grip tires seem to have all the right stuff from an
efficiency standpoint-- relatively thin, smooth treads with tapered
edges; thin, high thread count casings; time-proven lampblack tread
rubber; and modestly wide sizes available. I have yet to find a tire
that feels more efficient in any given size than Avocet slicks. My
favorite has been the 26 x 1.9" size, which unfortunately is no longer
manufactured.

That's interesting, Avocet still list a Fasgrip City and Fasgrip City
K in 26x1.9, both with 66 tpi too!

http://avocet.com/tirepages/carbon12_specs.html

The main problem with Avocet has always been their screwed up,
antiquated distribution system (or lack thereof). Supposedly, any LBS
should be able to order tires directly from Avocet. Good Luck with
that!

Why bother when you can get Performance/Nashbar slicks that are 95% as
good, for $9.99, and get 'em in a couple of days -- instead of waiting
weeks for the privilege of paying $30/tire.

Matt O.

Tim McNamara said:

Quoted message said:

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as
the tread wears off.

Quoted message said:

That would make sense. Heine also thought there is a "break-in"
period in which the casing "loosens up," but I have never seen that
mentioned anywhere else.

You'll need to explain what you mean by "loosen up". If you mean
delamination, that doesn't lower internal losses in a tire because it
adds sliding friction to elastomeric losses. Rolling resistance of
tires in god condition is almost entirely hysteretic losses in
elastomers, tread, tube, sidewall rubber and inter-ply binders.

I have not seen a tire develop separated cords even when worn through
the tread exposing these cords.

Jobst Brandt

Matt O'Toole said:

Quoted message said:

So, the question is how do you tell whether a tire is build around
*fast* casing or "slow" casing? Or, is this just a myth?

Quoted message said:

Put it on a test rig and test it for rolling resistance.

Well, what do you call a "fast casing"? The classic definition of low
RR tires has often been based on (actual) TPI (threads per inch) of
the casing. TPI tells approximately thickness of a casing ply of which
a bicycle tire has two. This can be determined by actual count or by
measuring the thickness of the sidewall for comparison with a tire of
known low RR.

Wall thickness is a measure of how much elastomer surrounds casing
fibers and resultant casing bending stiffness, that being the cause of
flexural losses in a tire. Beyond that, tread thickness plays a major
role. Generally tires with high TPI have relatively thinner treads,
not wanting to throw away in tread losses what was gained in a more
expensive casing. Kevlar and other anti puncture plies generally
place tires in the high RR category so they need not be considered in
this respect.

The thump-with-the-finger ring test isn't bad, because it measures
damping (losses) in the tire at a given inflation pressure. This is a
good comparison. In the days of yore, it was a pleasure to thump Tipo
00 Clement track tires and listen to them ring

Jobst Brandt

In article <[email hidden]>,

Matt O'Toole said:

Tim McNamara said:

There's a "break point" at which the tire is too wide to use a thin
casing made with fine gauge thread due to casing tension. IIRC
that is about 25-28 mm. Tires wider than that need a heavier
casing such as a 66 tpi fabric.

There may be a technical limitation, but I suspect the "break point"
is determined by the market.

From previous discussions there is an issue with casing tension- as the
casing gets larger in minor diameter, the tension on the casing at the
same inflation pressure increases significantly. At some point, it is
necessary to use a heavier casing. IIRC that point is in the 25-28 mm
range.

Quoted message said:

Most people who want fast tires want 23mm ones, whether they should
or not. Riders or product managers who want >25mm tires want
durable, cheaper ones.

The latter, I think- products offered to the public are the products
that product managers and the like imagine the public wants. The idea
that the public might actually want a 28 mm wide high performance tire
tends to elude them. There is a tendency to assume 28 mm tires are used
by commuters and tourists.

Quoted message said:

Also, sizes are only nominal. A 28mm Conti is narrower than a 25mm
Michelin.

I've measured both at 26 mm using a calipers. Same as the Panaracer
Pasela 700 x 25. ISTR that the Avocet Road 700 x 28 measured an actual
25-26 mm (and is now marked as such).

In article <[email hidden]>,

Quoted message said:

Tim McNamara said:

Quoted message said:

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as
the tread wears off.

Quoted message said:

That would make sense. Heine also thought there is a "break-in"
period in which the casing "loosens up," but I have never seen that
mentioned anywhere else.

You'll need to explain what you mean by "loosen up".

He didn't define it. From context it seemed that he thought that the
casing becomes more supple over the first 200 km or so as the tire
"breaks in." I've not seen this mentioned anywhere else and I'm not
sure what mechanism Jan had in mind.

What I have seen mentioned is that when tires are first mounted and
inflated, they stretch a bit. I've measured this with calipers, pumping
my new tires up to the identified pressure in the evening and
remeasuring the next evening, finding that the tire is 1-2 mm wider and
the pressure has dropped a few psi. The latter might just be due to
osmosis, although if the casing does stretch a bit overnight then the
volume would increase and the pressure would drop a bit.

It seems to me that the casing new tires feels stiffer than used tires,
but then with used tires the tread is worn down and thinner so it's not
an apples to apples comparison.

Quoted message said:

If you mean delamination, that doesn't lower internal losses in a
tire because it adds sliding friction to elastomeric losses. Rolling
resistance of tires in god condition is almost entirely hysteretic
losses in elastomers, tread, tube, sidewall rubber and inter-ply
binders.

That makes sense.

Quoted message said:

I have not seen a tire develop separated cords even when worn through
the tread exposing these cords.

I've had several tires suffer cord separation, always along the bias
angle between adjacent cords. Two Ritchey Tom Slicks in 700 x 25, two
or three Tom Slicks in 26 x 1.0. One end of the separation always went
to or started from the pronounced sipe along the side of the tires, and
the cords would separate enough to allow the inner tube to poke through.
(I no longer use Tom Slicks). On a 65 miler on Sunday with a couple of
friends, I had a similar failure with a Panaracer Pasela 26 x 1.25 but
the cord separation was located in the center of the tread, about 5 mm
long and again oriented along the bias angle and between adjacent cords.
The edges wore through the inner tube causing a flat. That was how I
discovered the casing failure. I booted it and was able to ride home
with no further problems.

I've not had other people tell me of similar failures, so I wonder if it
is something specific to me. I inflate the tires to the maximum marked
on the sidewall using a Silca Super Pista pump which, as far as I know,
has an accurate gauge within a few PSI (at least when compared to
another Presta valve gauge I have). The failures have been in tires
used on the front as well as the rear wheel. There has always been at
least half of the tread left on the tire. There has been no visible
external damage such as a cut.

Tim McNamara said:

Quoted message said:

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as
the tread wears off.

Quoted message said:

That would make sense. Heine also thought there is a "break-in"
period in which the casing "loosens up," but I have never seen that
mentioned anywhere else.

You'll need to explain what you mean by "loosen up". If you mean
delamination, that doesn't lower internal losses in a tire because it
adds sliding friction to elastomeric losses. Rolling resistance of
tires in good condition is almost entirely hysteretic losses in
elastomers, tread, tube, sidewall rubber and inter-ply binders.

I have not seen a tire develop separated cords even when worn through
the tread exposing these cords.

Jobst Brandt

Quoted message said:

Tim McNamara said:

Quoted message said:

To follow up on some of Tim's comments (though not related to the
casing issue), I'm pretty sure a tires rolling resistance drops as
the tread wears off.

That would make sense. Heine also thought there is a "break-in"
period in which the casing "loosens up," but I have never seen that
mentioned anywhere else.

You'll need to explain what you mean by "loosen up". If you mean
delamination, that doesn't lower internal losses in a tire because it
adds sliding friction to elastomeric losses. Rolling resistance of
tires in good condition is almost entirely hysteretic losses in
elastomers, tread, tube, sidewall rubber and inter-ply binders.

I have not seen a tire develop separated cords even when worn through
the tread exposing these cords.

Jobst Brandt

I have several questions about tires and rolling resistance.

A clincher has been proven to have a lower rolling resistance than a
tubular because of hystersis. From what I can tell though all the
tests have been done with road tubular glue. The difference seems to
be about 5-10 watts. How much will track glue lower the difference?

Higher inflation pressures mean a lower rolling resistance but, as I
understand it, that is for smooth surfaces like wood tracks, steel
drums etc. In real life out on the road the transfer of energy means
lower pressures outperform high pressures. Am I correct, and how do
you determine the correct pressure for a given situation (eg one tire
brand and a given surface).

Thanks

PS for Jobst. The graph of rolling resistance values for different
tires in your 2004 article hosted on Sheldon Brown doesn't give a good
description of the various tires. Is there a link somewhere to the
brands so that we can tell where the tubulars ranked?.