Road tire life span


Tom Sherman

Tim McNamara wrote:

> ... If one wishes to see lots of crashes due to such
> slippage, watch the 1993 men's road race championships in
> Oslo Norway....

Sorry, my time machine is out of commission. ;)

Tom Sherman – Quad City Area

Jobst Brandt

Dave Lehnen writes:

>> I am curious about the tires these riders used on that
>> course. From what I have seen, many racers ride on
>> colored tires, some of which make all sorts of claims to
>> have more traction on the side than the middle depending
>> on color stripes. This is so much BS because a rider
>> needs maximum traction when braking before a curve while
>> upright as well as needing it to get around the corner.
>> There is no excuse except fashion to have any less
>> traction than the best on the entire tread and that is
>> presently still gotten only with carbon black tread.

> Since maximum braking when upright is limited by the angle
> from the front contact patch to the center of gravity, as
> often discussed on this newsgroup, traction greater than
> required to raise the rear wheel does not provide better
> deceleration. Even the hardest- compound touring tires
> seem capable of lifting the rear wheel, at least in dry
> conditions.

I think you'll find that braking in the wet can skid the
front tire before the rear wheel lifts but that is less than
the whole story. In poor traction, rear wheel braking is
also needed and compromising that which carbon black tires
offer has caused crashes even while braking.

> When cornering, acceleration is limited only by traction.
> It would make sense to trade off some tread life, or
> rolling resistance, or cut resistance, if it would help
> traction, on the side tread.

That may be the thinking of those who have different center
stripes from edge tread but they are inconsistent, some
having the color on the sides and black in the center,
others having the converse. I suspect that both colored and
black are silica filled instead of carbon.

> Since bicycles can't brake at much more than about 0.6g,
> it would make sense to optimize the center tread for other
> desirable properties, as long as traction was more than
> could be used anyway.

Not on my bicycle. I have ridden enough wet mountain passes
and exceeded traction often enough to not mess with even
poorer traction that I had on carbon tires.

>> People who say otherwise are either lying or are as
>> uneducated in the matter as the public on whom they pass
>> this sort of hype is. The former is probably true, there
>> not being an excess of tribological expertise in the
>> bicycle business, judging from the faux pas we see
>> regularly. I recall when Umma-Gumma, non black, tires
>> were foisted on the 7-Eleven team for their lower RR but
>> were so bad in the wet that crashes rapidly got them back
>> to the supplier.

Jobst Brandt [email protected]

Jobst Brandt

Tim McNamara writes:

>>> If one wishes to see lots of crashes due to such
>>> slippage, watch the 1993 men's road race championships
>>> in Oslo Norway- a nasty wet day with lots of crashes
>>> resulting from the wheels slipping out on lane stripes.
>>> Some of them looked quite painful. IIRC Ekimov actually
>>> went over a "Jersey wall" type barrier and landed on
>>> commuter railroad tracks.

>> I am curious about the tires these riders used on that
>> course.

> Boy, I have no idea and I don't have a copy of the video.
> I do remember quite clearly seeing riders slip out in
> turns as they crossed the heavy white painted stripes, the
> wheels going out almost instantaneously. There were some
> very painful looking crashes.

Well for slick material, all bets are off. Metal utility
covers, solid paint stripes, and crack sealant are slick
to any kind of rubber. It's the rider's business to not
demand any side forces from such surfaces. Of course, in
a dense pack of riders, that may not be visible until it
is too late.

I once watched a video of a Paris-Roubaix rider go down on a
straight section of basalt cobbles just from the inter
cobble rounded seams. I recall in the days of yore I would
demonstrate this with my car at a low rolling speed and run
it up through the gears on wet basalt without gaining more
than 2-3mph while the tachometer registered 3000rpm in 3rd
(of 4) gear. That makes a badly floating rear end if you
aren't on a level street.

Jobst Brandt [email protected]

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