Just curious ... tire question

wrote in message ...
In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for racing,
a 25mm for road and a 23mm for criteriums. I think the 25mm tire was
the culmination of much thought of the opposing demands. Before that,
on rough dirt roads 26 and 27mm tubulars existed but they went away as
pavement took over. Tire cross section is governed mainly by the
cushion required to keep the rim from hitting the road under
reasonable inflation (about 100psi).

Super slender tires (19mm) are being offered because there is a demand
for "something else" although they don't offer any advantages. It
took a long time for smooth tread to become standard (again) from the
days of tubulars of the pre WW2 era. Fashion and pseudo science, more
than ever, is running rampant in the bicycle business today.

See the resurgence of slots in saddles (from the 19th century) paired
spoke wheels (from the 19th century), sloping top tubes and curved
stays, all old hat but once again popular.

1901

It was now possible for cycle tyres to have tread patterns, since they were
fully moulded articles. The pattern was produced by turning, milling and
engraving the iron or steel tread rim of the Doughty mould. The earliest
designs were plain circumferential ribs. ... ...

And so this pattern lasted, at lest until mid 1980's 27" tubular -- 1
5/8" approx 40mm It is reasonable for a 14 stone rider to use 80psi in a
23mm tubular. It is possible for the same rider to use that same tyre at
40psi safely. Cautiously but safe.

Trevor

wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Pete Cresswell writes:

Clement even had a road tire with the same casing as...

How about another historical question?

Some old Brooks saddle catalogs refer to this or that saddle as a
"Path" saddle. Any idea what they're referring to?

e.g.
http://www.brooksarchives.info/brook...oks/page8.html

From the picture in that catalog I see that it has a fairly thin wire
frame with four elements instead of two. Other than that it appears
to be the same as the others. That would mean that Brooks believed
there was perceptibly more elasticity in that model. In contrast I
propose that it did not or the rails would have broken even faster
than their SStl saddle frames.

Sturmey Archer and Brooks are noted for their stuck-in-the-mud
technical skills. They had plenty of failures that should have given
them a clue. Even 100 years ago stress and strain was computable as
we see in some of the greatest steel structures that were built by
British engineers in that era and still standing today. As today,
there aren't many top engineers engaged in the bicycle business.

Jobst Brandt

On Fri, 20 Aug 2004 04:46:41 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Dear Trevor,

I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)

For the same tire pressure, a wider tire has a shorter,
rounder contact patch, which offers more resistance to a
localized impact than the narrower, elongated contact patch
of a thinner tire.

As an example, first imagine utterly flat profile tires, one
an inch wide and the other two inches wide, each pumped up
to 100 psi and each bearing 200 pounds.

The thin tire has a 2-inch long contact patch an inch wide,
two square inches supporting 200 pounds.

The wide tire has a 1-inch long contact patch two inches
wide, so again two square inches support 200 pounds.

Now press a spoke across each tire sideways, simulating a
nasty impact hoping to give you a pinch flat.

On the thin tire, the spoke has to compress only an
inch-wide strip of tire against 100 psi.

On the wide tire, the spoke has to compress a two-inch wide
strip of tire against the same 100 psi--twice as much
resistance.

Carl Fogel

On Fri, 20 Aug 2004 04:20:52 +0100, "Trevor Jeffrey"
wrote:


wrote in message
In addition to the lubrication mentioned by other posters, a
wet front tire simply flips up far more sharp debris that
was lying harmlessly flat on the road and thus increases the
chances that the rear tire will be impaled.

I'd have thought that would make a clear path for the rear tyre by throwing
it to the side, do you have any photographic evidence to support this? Are
you just repeating what others have said and will say?

Trevor

Dear Trevor,

Think of a small, pointy piece of debris lying flat on the
road.

Flip that piece of debris up a little by rolling a tire over
it at speed.

It isn't flung to the side, just rattled and tilted up.

Now run your rear tire over it.

Eventually, a piece of debris will be at the right angle to
impale the rear tire. The water increases how many pieces
are flung up and how far.

Without this flip-up process, purely pointy debris like
nails would never puncture tires on hard, flat roads.
Unicycles are safe from nails lying flat on pavement.

This flip-up process works for sharp-edged debris, too. A
typical glass shard lies flat, with its least threatening
surface waiting for the tire, like a broken knife blade
lying harmlessly flat on the floor. But rattle it, tilt it,
or flip it up a little, and now the sharp edge is up and
ready to lacerate a tire.

Your idea of the front tire sweeping a clear path works to
some extent with caltrop-shaped debris, like goathead
thorns. A front tire will easily pick up a goathead and
possibly save the rear tire.

If you're not sure that a wet front tire flings up lots of
debris, wait for the rain to stop, ride a mile along a wet
road, and look at the underside of your downtube and the
bottom bracket.

Carl Fogel

On Thu, 19 Aug 2004 20:35:51 GMT, wrote:

Benjamin Lewis writes:

In addition to those, I think the real reason is wet conditions
allow small pieces of debris to cling to the tire for a few more
revolutions, thereby having a better chance for a puncture. When
it's wet, it's just stickier all around.

This falls in the "wiping tires" category of bicycle lore. I think
other respondents covered the reasons adequately. On the other
hand, skinny tires do about everything worse that a larger tire
does within reasonable sizes except weight, which has no bearing on
a flat TT.

Just out of curiosity, where would you place the limit on
"reasonable sizes"?

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for racing,
a 25mm for road and a 23mm for criteriums. I think the 25mm tire was
the culmination of much thought of the opposing demands. Before that,
on rough dirt roads 26 and 27mm tubulars existed but they went away as
pavement took over. Tire cross section is governed mainly by the
cushion required to keep the rim from hitting the road under
reasonable inflation (about 100psi).

Super slender tires (19mm) are being offered because there is a demand
for "something else" although they don't offer any advantages. It
took a long time for smooth tread to become standard (again) from the
days of tubulars of the pre WW2 era. Fashion and pseudo science, more
than ever, is running rampant in the bicycle business today.

See the resurgence of slots in saddles (from the 19th century) paired
spoke wheels (from the 19th century), sloping top tubes and curved
stays, all old hat but once again popular.

Are you trying to tell us that the laws of physics have not changed in all those
years? That a well-engineered solution to a problem is still a valid solution to
that same problem even if that solution is more than ten years old?

You really need to get help.

Ron

wrote in message
...
On Fri, 20 Aug 2004 04:46:41 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Dear Trevor,

I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)

For the same tire pressure, a wider tire has a shorter,
rounder contact patch, which offers more resistance to a
localized impact than the narrower, elongated contact patch
of a thinner tire.

As an example, first imagine utterly flat profile tires, one
an inch wide and the other two inches wide, each pumped up
to 100 psi and each bearing 200 pounds.

The thin tire has a 2-inch long contact patch an inch wide,
two square inches supporting 200 pounds.

The wide tire has a 1-inch long contact patch two inches
wide, so again two square inches support 200 pounds.

Now press a spoke across each tire sideways, simulating a
nasty impact hoping to give you a pinch flat.

On the thin tire, the spoke has to compress only an
inch-wide strip of tire against 100 psi.

On the wide tire, the spoke has to compress a two-inch wide
strip of tire against the same 100 psi--twice as much
resistance.


I am aware of these points.
Still no explanation of why narrow tyres are more suitable for criteriums.
Harder cornering may suggest to move away from the narrowest tyres. Poor
road surface also exists with crit's, so that's no explanation.

Trevor

On Tue, 24 Aug 2004 23:00:19 +0100, "Trevor Jeffrey"
wrote:


wrote in message
...
On Fri, 20 Aug 2004 04:46:41 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Dear Trevor,

I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)

For the same tire pressure, a wider tire has a shorter,
rounder contact patch, which offers more resistance to a
localized impact than the narrower, elongated contact patch
of a thinner tire.

As an example, first imagine utterly flat profile tires, one
an inch wide and the other two inches wide, each pumped up
to 100 psi and each bearing 200 pounds.

The thin tire has a 2-inch long contact patch an inch wide,
two square inches supporting 200 pounds.

The wide tire has a 1-inch long contact patch two inches
wide, so again two square inches support 200 pounds.

Now press a spoke across each tire sideways, simulating a
nasty impact hoping to give you a pinch flat.

On the thin tire, the spoke has to compress only an
inch-wide strip of tire against 100 psi.

On the wide tire, the spoke has to compress a two-inch wide
strip of tire against the same 100 psi--twice as much
resistance.


I am aware of these points.
Still no explanation of why narrow tyres are more suitable for criteriums.
Harder cornering may suggest to move away from the narrowest tyres. Poor
road surface also exists with crit's, so that's no explanation.

Trevor


Dear Trevor,

I said it once in my first paragraph, but I'm happy to say
it again:

"I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)"

Carl Fogel

wrote in message
...
On Tue, 24 Aug 2004 23:00:19 +0100, "Trevor Jeffrey"
wrote:


wrote in message
.. .
On Fri, 20 Aug 2004 04:46:41 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Dear Trevor,

I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)

For the same tire pressure, a wider tire has a shorter,
rounder contact patch, which offers more resistance to a
localized impact than the narrower, elongated contact patch
of a thinner tire.

As an example, first imagine utterly flat profile tires, one
an inch wide and the other two inches wide, each pumped up
to 100 psi and each bearing 200 pounds.

The thin tire has a 2-inch long contact patch an inch wide,
two square inches supporting 200 pounds.

The wide tire has a 1-inch long contact patch two inches
wide, so again two square inches support 200 pounds.

Now press a spoke across each tire sideways, simulating a
nasty impact hoping to give you a pinch flat.

On the thin tire, the spoke has to compress only an
inch-wide strip of tire against 100 psi.

On the wide tire, the spoke has to compress a two-inch wide
strip of tire against the same 100 psi--twice as much
resistance.


I am aware of these points.
Still no explanation of why narrow tyres are more suitable for criteriums.
Harder cornering may suggest to move away from the narrowest tyres. Poor
road surface also exists with crit's, so that's no explanation.

Trevor


Dear Trevor,

I said it once in my first paragraph, but I'm happy to say
it again:

"I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)"

Why should crit's be less rough? Riding over kerbs and wheels does not make
a smooth path.

Trevor

On Wed, 25 Aug 2004 21:13:22 +0100, "Trevor Jeffrey"
wrote:


wrote in message
...
On Tue, 24 Aug 2004 23:00:19 +0100, "Trevor Jeffrey"
wrote:


wrote in message
. ..
On Fri, 20 Aug 2004 04:46:41 +0100, "Trevor Jeffrey"
wrote:


wrote in message ...
Matthew C Roberts writes:

In the days of yore when fashion had little affect on such things,
tubular tire manufacturers made mainly two sizes of tires for
racing, a 25mm for road and a 23mm for criteriums.

If you'll pardon my ignorance, why the narrower tires for crits?

Because they are held on smooth city streets. If the route does not
fit that description, road tires are in order. Of course this is not
considered by some riders and they get snake bite flats. On a road
race, you can encounter most anything.

Clement even had a road tire with the same casing as their Campionato
del Mundo road tire but with a narrower and thinner tread for a one
day classic called Paris-Roubaix.

Answer the question. Why narrow tyres for criteriums?

Or why wide tyre when not in criteriums?

Trevor

Dear Trevor,

I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)

For the same tire pressure, a wider tire has a shorter,
rounder contact patch, which offers more resistance to a
localized impact than the narrower, elongated contact patch
of a thinner tire.

As an example, first imagine utterly flat profile tires, one
an inch wide and the other two inches wide, each pumped up
to 100 psi and each bearing 200 pounds.

The thin tire has a 2-inch long contact patch an inch wide,
two square inches supporting 200 pounds.

The wide tire has a 1-inch long contact patch two inches
wide, so again two square inches support 200 pounds.

Now press a spoke across each tire sideways, simulating a
nasty impact hoping to give you a pinch flat.

On the thin tire, the spoke has to compress only an
inch-wide strip of tire against 100 psi.

On the wide tire, the spoke has to compress a two-inch wide
strip of tire against the same 100 psi--twice as much
resistance.


I am aware of these points.
Still no explanation of why narrow tyres are more suitable for criteriums.
Harder cornering may suggest to move away from the narrowest tyres. Poor
road surface also exists with crit's, so that's no explanation.

Trevor


Dear Trevor,

I said it once in my first paragraph, but I'm happy to say
it again:

"I think that Jobst's point is that wider tires are less
likely to pinch-flat on nasty bumps, so they're used where
rougher riding is expected. (Narrower tires are lighter and
reduce wind drag, but perform poorly when flat.)"

Why should crit's be less rough? Riding over kerbs and wheels does not make
a smooth path.

Trevor


Dear Trevor,

Your better riders try not to ride over curbs or the wheels
of other riders.

Carl Fogel