Road tire life span

Tim McNamara writes:

That fits the description of a temporary loss of traction below the
limit. It is similar to slipping across a slick spot or a spot of
sand on the road. Once the lean angle exceeds the traction there
is no return to stability.

I've had slight slippages like that occur in races crossing the lane
striping; slipping on these is much more pronounced when it is wet,
of course. But the width of the excursion, if that's the correct
term, is only a couple of inches and then once you're off the stripe
you're back on pavement with a high coefficient of friction. Front
wheel slippage seems to be less recoverable than rear wheel
slippage.

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. 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.

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

wrote:


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.

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.

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.

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


Dave Lehnen

writes:

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.

wrote in message
...

I have yet to see a cyclist crash or go down on DRY payment when
leaning too far into a turn.

I have and did so myself in years past. That's called low-siding when
the bicycle goes out from under the rider. Low side because the
distance to the ground is relatively small. High-siding is worse
because the rider goes up and over the bicycle and hits harder. My
friend did that on Mt. Hamilton recently on the day of the bicycle
race... Collar bone + two ribs.

I didn't think "High-siding" was possible on a bicycle until I saw Joseba
Beloki do it in last years Tour de France. I believe that was due to melted
tar at high speeds through a turn. I'm thinking he might have hit the rear
brake.

I'm don't worry much about my cornering ability , but more concerned about
the road condition on high speed descents. My hardest fall was when someone
put sand on the road during the winter to help melt the ice. The roads were
dry, but I lost traction on the sand. I also slipped and almost lost it on
the back side of Mt. Hamilton due to some gravel on the road.
-tom

g.daniels wrote:

what happened to walnut shells?

Like you, they're cracked.

Bill "ty...tyvm" S.

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

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

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