Just curious ... tire question

Watching The Lance Interview while spinning on the rollers the other
evening, he commented on the poor judgement of teams like Phonak to ride
19mm tires during the TTT when Postal used "the fatest, ugliest tires we
could find." He said, "everyone knows that, in wet and rainy conditions,
you're more prone to flats and that's exactly what happened (to Phonak)."
(That's an approximate quote ... not an exact one.)

So the question is, why is this true? (And I know it is from personal
experience.) Why should a tire be more prone to a flat when the road is wet
than if it's dry? I can't come up with any logical reason that should be
true. I'd intuitively opt for larger tires in those conditions for a larger
contact patch and, hopefully, better handling in technical sections. But
what's up with flats in the wet?

Bob C.

The stresses in the contact patch differ due to the lubricating effect
of the water. When a tire deforms to make the contact patch, th
contact area contracts as it is now flat and not curved. On dr
ground, this manifests itself as compressive stress in the rubber.
Water lowers the coefficient of friction and lowers the compressiv
stress in the rubber, making it easier for a sharp stone, glass o
other debris cut the tire. The water also lubricates the friction o
the cutting edge, allowing it to penetrate deeper.

Wider tires require less pressure and have shorter contact patches.
These add to puncture resistance, all other things considered equal

--
Weisse Luft

psycholist wrote in message ...
Watching The Lance Interview while spinning on the rollers the other
evening, he commented on the poor judgement of teams like Phonak to ride
19mm tires during the TTT when Postal used "the fatest, ugliest tires we
could find." He said, "everyone knows that, in wet and rainy conditions,
you're more prone to flats and that's exactly what happened (to Phonak)."
(That's an approximate quote ... not an exact one.)

So the question is, why is this true? (And I know it is from personal
experience.) Why should a tire be more prone to a flat when the road is
wet
than if it's dry? I can't come up with any logical reason that should be
true. I'd intuitively opt for larger tires in those conditions for a
larger
contact patch and, hopefully, better handling in technical sections. But
what's up with flats in the wet?

In the dry rubber is resistant to cutting due to its high coefficient of
friction. Water acts as a lubricant and allows the thorn or glass shard to
penetrate with less force. The larger tyre allows a lower tyre pressure,
thereby reducing the force available to penetrate the tyre.

Trevor

On Wed, 18 Aug 2004 15:33:33 -0400, "psycholist"
wrote:

Why should a tire be more prone
to a flat when the road is wet
than if it's dry?

The water lubricates objects on the road, so they can more easily
slice into the tire. Sometimes rain also washes more grit out onto
the road.

JT

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On Wed, 18 Aug 2004 15:33:33 -0400, "psycholist"
wrote:

Watching The Lance Interview while spinning on the rollers the other
evening, he commented on the poor judgement of teams like Phonak to ride
19mm tires during the TTT when Postal used "the fatest, ugliest tires we
could find." He said, "everyone knows that, in wet and rainy conditions,
you're more prone to flats and that's exactly what happened (to Phonak)."
(That's an approximate quote ... not an exact one.)

So the question is, why is this true? (And I know it is from personal
experience.) Why should a tire be more prone to a flat when the road is wet
than if it's dry? I can't come up with any logical reason that should be
true. I'd intuitively opt for larger tires in those conditions for a larger
contact patch and, hopefully, better handling in technical sections. But
what's up with flats in the wet?

Bob C.


Dear Bob,

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.

Carl Fogel

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.

wrote in message
...
On Wed, 18 Aug 2004 15:33:33 -0400, "psycholist"
wrote:

Watching The Lance Interview while spinning on the rollers the other
evening, he commented on the poor judgement of teams like Phonak to ride
19mm tires during the TTT when Postal used "the fatest, ugliest tires we
could find." He said, "everyone knows that, in wet and rainy conditions,
you're more prone to flats and that's exactly what happened (to Phonak)."
(That's an approximate quote ... not an exact one.)

So the question is, why is this true? (And I know it is from personal
experience.) Why should a tire be more prone to a flat when the road is
wet
than if it's dry? I can't come up with any logical reason that should be
true. I'd intuitively opt for larger tires in those conditions for a
larger
contact patch and, hopefully, better handling in technical sections. But
what's up with flats in the wet?

Bob C.


Dear Bob,

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.

Carl Fogel




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Roger Moore 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.

Jobst Brandt

jobst brandt wrote:

Roger Moore 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"?

--
Benjamin Lewis

TO ARMS! TO ARMS! Hooray! That's great
Two legs ain't bad unless there's a crate
They ship the parts to mama in. -- FZ

"Roger Moore" wrote in message ...
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.

Don't let Jobst hear you say that. I agree with the FAQ, in that
water acts as a lubricant in cutting rubber. Try it for yourself with
a razor blade and an old tire.


Robin Hubert


wrote in message
...
On Wed, 18 Aug 2004 15:33:33 -0400, "psycholist"
wrote:

Watching The Lance Interview while spinning on the rollers the other
evening, he commented on the poor judgement of teams like Phonak to ride
19mm tires during the TTT when Postal used "the fatest, ugliest tires we
could find." He said, "everyone knows that, in wet and rainy conditions,
you're more prone to flats and that's exactly what happened (to Phonak)."
(That's an approximate quote ... not an exact one.)

So the question is, why is this true? (And I know it is from personal
experience.) Why should a tire be more prone to a flat when the road is
wet
than if it's dry? I can't come up with any logical reason that should be
true. I'd intuitively opt for larger tires in those conditions for a
larger
contact patch and, hopefully, better handling in technical sections. But
what's up with flats in the wet?

Bob C.


Dear Bob,

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.

Carl Fogel




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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.

Jobst Brandt