Tire rot

In article
,
wrote:

On Mar 11, 1:31*pm, wrote:
On Tue, 11 Mar 2008 06:17:22 -0700 (PDT), datakoll

wrote:
bikes tires flatten if left in one position. Auto tires do it, people
do it, rocks do it, wine and beer do it, glass does it-glass is a
fluid.

Actually, it's a well-refuted myth that glass windows flow and sag
under gravity:

http://groups.google.com/group/rec.b...0d41637743b6c1

Some old glass windows do indeed look as if they have sagged, but they
looked that way the day they were set in the frame.

I remember my old grade 8 teacher telling us that glass is a very very
slow liquid- but then I discovered he was an idiot as almost all the
incredulous nonsense he taught was just that. well mr sharp; turned
out you weren't so sharp at all...sincerely, former student

Flow rate is proportional to, among other things, the curvature
of the surface. If glass flowed, the sharp corner of a glass
shard should dull rapidly. Such is not the case. Glass knives
hundreds of years old have their edge.

--
Michael Press

In article
,
datakoll wrote:

UNNNGH,

WHEN THE Cathedral at Chartes was restored, rumor was or is,
measurments made on stained glass set in uhuhuh 1237? showed glass was
wider at bottom than at top, that measurments conformed to equations
for glass flow.
Glass is typed as a solid liquid thru crystalized molecular structure.

That is now incorrect? My day is ruined.

Older tires set out in Florida's sun degrade without significant ozone
not so much newer compounds.

Look up glass transition temperature.
We all had this discussion not too long ago.

--
Michael Press

In article ,
wrote:

The tires of cars parked on streets survive years of sunlight.

The rubber is made with a sacrificial compound.
The sacrificial compound reacts more rapidly with
ozone and forms a powder layer on the tire.
If you want to protect the tire, leave it on there
and do not attack your tires with costly
products that only make it look shiny and
leaves black goo on any part of your person
that touches it.

--
Michael Press

In article ,
John Henderson wrote:

Tom Keats wrote:

In article ,
Just A User writes:
Can someone point me in the direction of a photo of the
damage that might occur from storing a bike with its tires on
a cold concrete floor.

In residential basements, it's not the cold concrete
floor that accelerates tire deterioration, it's the
ozone created by nearby electric motors such as those
in central heating furnaces.

N.B: Rubber doesn't "rot" as in the biological sense
of the word. Rather, it gradually but inexorably
outgasses its more volatile chemical components, causing
the rubber structure to shrink, crack, and eventually
crumble. Ozone and ultraviolet light are reputed to
hasten the process. I think the latter factor (UV light)
is the greater concern.

I /have/ to store my main bike right beside the furnace.
But I wear my tires out just from daily use before the
furnace-motor ozone can kill 'em. But if I just permanently
left my bike out in a sunny spot in the back yard for a
year or two, (perish the thought) the tires would die long
before their time. If the bike wasn't stolen first.

As an aside thought, I also don't believe storing a bike
within a pyramid would prolong the the life of the tires ;-)
Now that I've said that, chances are Carl Fogel will try it.
You can put him up to almost anything that's tastefully and
non-destructively investigative/analytical/experimental G
(I say that with the utmost respect.)

I see that Michelin claims to have addressed this issue:

"PROTEK, a brand-new technology that is particularly effective
against damage caused by UV rays, ozone, temperature variations
and pinched tubes"

Automobile tires have been made with sacrificial compounds
for years. Michelin wants you to think that only they
do it.

--
Michael Press

Michael Press wrote:

Automobile tires have been made with sacrificial compounds
for years. Michelin wants you to think that only they
do it.

Perhaps the correct conclusion is that they've just started, as
far as bikes are concerned.

John

In article ,
John Henderson wrote:

Michael Press wrote:

Automobile tires have been made with sacrificial compounds
for years. Michelin wants you to think that only they
do it.

Perhaps the correct conclusion is that they've just started, as
far as bikes are concerned.

Do you suppose that bicycle tire manufactures went to
the trouble of making bicycle tire compound different
from the compound the use to make automobile tires?

--
Michael Press

Michael Press wrote:

In article ,
John Henderson wrote:

Michael Press wrote:

Automobile tires have been made with sacrificial compounds
for years. Michelin wants you to think that only they
do it.

Perhaps the correct conclusion is that they've just started,
as far as bikes are concerned.

Do you suppose that bicycle tire manufactures went to
the trouble of making bicycle tire compound different
from the compound the use to make automobile tires?

If they come from a different sub-contracting factory, then the
"trouble" might be the other way around.

John

wrote:

Dear John and Bob,

From the online BikePro catalogue section on bicycle tires,
roughly the same as in my 1994 copy:

"As a protective agent against UV damage tire makers use
additives that inhibit, but don't prevent UV damage, which act
as light absorbers such as Tinuvin P and the
2-hydroxybenzophenones. At time of vulcanization the zinc salt
of mercaptobenzimidazole (ZMBI) is introduced as an ingredient
to increase the resistance to heat degradation. In the same
process, to inhibit the effect of sunlight, 2% of nickel
dibutyldithiocarbamate may be used. Atmospheric oxygen attacks
rubber slowly, which causes it to become hard and brittle, so
relatively insoluble waxes are incorporated into the tire
compound which migrates or blooms to the rubber surface,
protecting it until the wax surface is broken. The
incorporated wax produces a whitish tinge on a new tire when
it is rolled tightly between the fingers or possibly pinched."

http://www.bikepro.com/products/tires/tireover.html

Thanks Carl. I'd expect that this "anti-aging" technology is
improving as time goes on. Michelin is a reputable company,
and I'd expect at least a significant reformulation if they're
going to make a public announcement about it.

I took delivery of a new "Michelin City" tyre only a couple of
days ago, and that's what prompted me to search for "Protek
plus", as mentioned on the label and on tyre itself.

What impresses me most about this tyre is the inflation
pressure. It's 26 x 1.85 (and big for that size - a little
wider than a 26 x 2.00 Schwalbe). The maximum inflation
pressure is 87 PSI.

John

On Thu, 13 Mar 2008 03:08:16 GMT, still just me
wrote:

On Thu, 13 Mar 2008 06:05:43 +1100, John Henderson
wrote:

Do you suppose that bicycle tire manufactures went to
the trouble of making bicycle tire compound different
from the compound the use to make automobile tires?

If they come from a different sub-contracting factory, then the
"trouble" might be the other way around.

I don't think it's "trouble" so much as "blend". Down at the rubber
product (pick one) factory, they blend up different rubber mixes for
each product they produce. It's not so much "trouble" as it is
standard fare in the industry. I'm quite certain that bicycle tires
are made with different compounds than auto tires (in fact, the rubber
blend from one auto tire model to the next varies substantially).

Dear John and Bob,

From the online BikePro catalogue section on bicycle tires, roughly
the same as in my 1994 copy:

"As a protective agent against UV damage tire makers use additives
that inhibit, but don't prevent UV damage, which act as light
absorbers such as Tinuvin P and the 2-hydroxybenzophenones. At time of
vulcanization the zinc salt of mercaptobenzimidazole (ZMBI) is
introduced as an ingredient to increase the resistance to heat
degradation. In the same process, to inhibit the effect of sunlight,
2% of nickel dibutyldithiocarbamate may be used. Atmospheric oxygen
attacks rubber slowly, which causes it to become hard and brittle, so
relatively insoluble waxes are incorporated into the tire compound
which migrates or blooms to the rubber surface, protecting it until
the wax surface is broken. The incorporated wax produces a whitish
tinge on a new tire when it is rolled tightly between the fingers or
possibly pinched."

http://www.bikepro.com/products/tires/tireover.html

Cheers,

Carl Fogel