Road tire life span



T

Tim McNamara

Guest
Benjamin Lewis <[email protected]> writes:

> Selling tires is important to tire manufacturers. Why
> would improving traction be important to them if consumers
> don't demand it, or believe their claims without examining
> any data? The goodness of their hearts?

Preventing expensive lawsuits? What the tire manufacturers
are banking on is that the vast majority of bike riders just
want to look like they could go fast, rather than actually
going fast and operating the equipment at the limits of
functionality. These people never remotely approach the
margins of safety.

People like Jobst- and perhaps you- who live near and
frequently ride in mountains push the equipment much closer
to the limits than I do, living as I do in flat to rolling
terrain and no longer racing. To those folks, whose health
and possibly survival is dependent on the equipment
functioning properly, traction is a rather important feature
in a bike tire. I was much more aware of traction as an
issue two summers ago when I rode in the Alps, riding tight
corners with long drops to the outside; in the Minneapolis-
St. Paul area there is just nothing at all like that.
Stopping traction is more important for avoiding getting
mashed by some latte-swilling SUV driver yakking on their
damned cell phone.
 
J

Jobst Brandt

Guest
Rick Onanian writes:

>>> Your paved-drum/leaned-bike experiment sounds like a
>>> reasonable, if imperfect, test method for fictional
>>> roads made of perfectly clean and perfectly flat
>>> pavement. I rarely find roads like that, and when I do,
>>> the new-pavement fumes make riding somewhat unpleasant.

>> Maybe you can explain what is "imperfect about this test.

> The shape of the contact patch is different; the tire must
> conform to the drum's convex shape. Further, it sure
> sounds like a perfect surface, unlike a road surface,
> which is rarely so.

I think you'll find that a six foot diameter is adequate to
approximate a road for test purposes, considering the
contact patch length of a normally inflated tire. Besides,
this is a comparative test and the values it produced are
repeatable and close enough from road values for side slip
that one cannot readily see a difference.

What is it that the drum diameter obscures?

>>>> I have experienced such slips often and even done so
>>>> crossing smooth paint stripes in the rain, but I don't
>>>> attribute those incidents to the tire but rather to
>>>> sand on the road or a slick wet spot. We ARE talking
>>>> about handling ability of one tire over another.

>>> Yes, but what good is it to know the handling ability on
>>> perfect pavement when we don't ride on such surfaces? We
>>> ride on roads with a bit of sand or a slick wet spot.
>>> Knowing the handling ability of a tire for such
>>> conditions is immensely more useful.

>> Let's not get into philosophy.

> What philosophy? I ride on real roads, with imperfect
> pavement, sometimes with sand or a slick wet spot. If a
> tire can't give a little and let me know before I suddenly
> find it airborne (and my body grounded), I want the BEST
> handling tire I can get.

Perfection is philosophical. Besides, if you cannot control
the test conditions you cannot perform the test. What you
are suggesting is that such tests cannot be performed
because roads vary too much. Such tests are performed on
standardized conditions that give typical best values. The
user must estimate what degraded conditions he is
encountering that will give poorer results, such as loose
gravel, oil, slick spots and the like.

>> You claim to have slid tires on clean dry pavement and I
>> said that is not a recoverable condition so it

> I claim to have slid tires on real pavement. I doubt it
> was perfectly clean, and I doubt it was perfectly flat,
> although I didn't feel bumps.

Lets get away for your definition of "real pavement" and use
pavement like that in the picture I attached:

http://tinyurl.com/2gbsj

I think that is real enough and Pescadero Road has a few of
these curves with "real" pavement at about 40mph.

I'm sure you didn't slip in a curve when banked over at near
45 degrees because that is unrecoverable. What were the
circumstances and what was the speed.

>> cannot be the criterion for handling among different
>> tires. We generally don't ride beyond the limit of
>> traction so the criterion must be something else. I'm
>> trying to get to the bottom of how you can give
>> comparative ratings to tires of similar size, inflation
>> and essentially smooth tread.

> I don't know how it can be done. IANAE. Something more
> realistic than a paved drum may be in order.

Again, what is it about a drum that you find deficient? It
is the common way tires are laboratory tested.

>>> Well, then we're not talking about a lot of precision
>>> here. Wheel imbalance can bounce a bike up and down in
>>> my hand at >20mph; that lifting/weighting force must
>>> affect the tire's load (and therefore, contact patch)
>>> each revolution.

>> I doubt that.

> Which part do you doubt? That the wheel can bounce the hand-
> held bike at >20mph, or that such a force must affect the
> tire's connection to the road?

Both. As I have explained at length.

> The first part can be tested by holding the rear of the
> bike a foot off the ground, and using the other hand to
> pedal it up as fast as you can. Mine provides a definite
> up-and-down motion, which I experimentally corrected by
> balancing the wheel.

THAT is an unrealistic test.

>> Having descended at more than 50mph often without having
>> balanced wheels, I have not felt so much as a hint of
>> imbalance from my conventional wheels that are not
>> balanced. Besides that, as I

> I've never passed 45mph, but even at that speed, I either
> did not feel imbalance or wouldn't know it from road
> vibration.

>>> A rider can tell if he got through his favorite curve
>>> (which has real-world pavement) at a higher speed
>>> without any traction reduction.

>> Yes? How do you determine "traction reduction". This is
>> what is at the root of this subject and I propose that
>> you cannot sense this without exceeding the limit and
>> crashing. Therefore, claiming that one tire handles
>> better than another is an undefined subjective claim.

> I don't know how you determine it. I agree that such a
> claim would be subjective.

I know what it is and have crashed as well as having
measured it the test equipment I have described. I
don't think you have the information to make the
suppositions you do.

>> I repeat, you didn't slip on clean dry pavement. I don't
>> claim that you didn't slip but it was for some reason
>> other than traction limitation of the tire. It was more
>> likely some foreign object on the road or a spot of some
>> lubricant.

> Like I said, real world road. Not a testing machine in a
> lab. I can't imagine how it could be tested.

Are you implying that the scene in the attached URL is not
real world. I ride around that curve in that manner often as
I do with many other curves. I also have piles of tires I
have worn to the cords as well as rims on which they served.
There are a lot of test miles accumulated.

I think you need to get out of your "real world" pavement
and get to reality.

Jobst Brandt [email protected]
 
T

Tom Nakashima

Guest
<[email protected]> wrote in message
news:MI%[email protected]...
> I know what it is and have crashed as well as having
> measured it the test equipment I have described.

Jobst, I have yet to see a cyclist crash or go down on DRY
payment when leaning too far into a turn. I have a crash on
wet payment as in the case of Jan Ulrich in last year's Tour
de France.

Is there a warning when you lean too far over in a turn that
would be unrecoverable and result in a crash. Is it possible
to recover if you have leaned too far over in a turn?

I'll have to say, you have a lot of guts to even attempt
this test. I could probably attempt this with full leathers
and a full face motorcycle helmet. -tom
 
R

Rick Onanian

Guest
On Tue, 22 Jun 2004 19:25:32 GMT, [email protected]
wrote:
>> The first part can be tested by holding the rear of the
>> bike a foot off the ground, and using the other hand to
>> pedal it up as fast as you can. Mine provides a definite
>> up-and-down motion, which I experimentally corrected by
>> balancing the wheel.
>
>THAT is an unrealistic test.

What do you find unrealistic about it? Are you not strong
enough to hold the rear of your bike up with one hand, and
pedal it in a high gear with the other?

That is a REAL, not just realistic, demonstration of a force
found in a moving bicycle. It is a force that we choose to
ignore, because it seems inconsequential; but if we're
talking about high-precision rating of tire handling
ability, it could make a difference, just as a bumpy road
makes a difference in traction. The casing of the tire would
affect how well it deals with the constant high frequency
load-unload cycle.
--
Rick Onanian
 
J

Jobst Brandt

Guest
Tom Nakashima writes:

>> I know what it is and have crashed as well as having
>> measured it the test equipment I have described.

> 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 have a crash on wet payment as in the case of Jan Ulrich
> in last year's Tour de France.

I've done that too, also low-side but broke a hip on one of
these. That was all years ago when I was "young and
beautiful" as ladies often say.

> Is there a warning when you lean too far over in a turn
> that would be unrecoverable and result in a crash.

None at all, and when it starts going it is obvious.
Judging from riders I pass down hills, few people ever get
close to that point on dry pavement. On wet roads it
occurs more often because the limit is so variable and is
hard to assess.

> Is it possible to recover if you have leaned too far over
> in a turn?

Not on dry pavement because there is nothing approaching
that will increase traction at that lean angle... that is
increasing rapidly as the slide progresses.

> I'll have to say, you have a lot of guts to even attempt
> this test. I could probably attempt this with full
> leathers and a full face motorcycle helmet.

I don't do such tests at speed. I ride below the limit, that
is more than most riders are willing to approach because
they haven't experienced the angle that is possible. It is
also good to have seen tires on a testing machine exceed 45
degrees to have a feel for what is reasonable.

Jobst Brandt [email protected]
 
T

Tom Sherman

Guest
Helmut Springer wrote:

> [email protected] wrote:
>
>>That depends on whether you think traction is an important
>>parameter.
>
> [...]
>
>>That for me falls into the definition "is important". How
>>can this not be important to a tire manufacturer?
>
>
> That is where engineering and marketing divide, and
> many will prioritize the latter as the market tends to
> reward it 8-/

This is true of human life in general: talking the talk
almost invariably is more rewarding than walking the walk.

--
Tom Sherman – Quad City Area
 
T

Tim McNamara

Guest
"Tom Nakashima" <[email protected]> writes:

> <[email protected]> wrote in message
> news:MI%[email protected]...
>> I know what it is and have crashed as well as having
>> measured it the test equipment I have described.
>
> Jobst, I have yet to see a cyclist crash or go down on DRY
> payment when leaning too far into a turn.

I've seen it in crits. Is there a warning? No- it's pretty
much instantaneous. Is it recoverable? Only by sheer luck.
My personal experience was with being leaned way over in a
crit and then striking a pedal, which lifted the rear tire.
I didn't crash, but that had everything to do with luck and
nothing to do with riding skills. Scared the hell out of the
guy on my wheel.
 
T

Tim McNamara

Guest
Rick Onanian <[email protected]> writes:

> On Tue, 22 Jun 2004 19:25:32 GMT,
> [email protected] wrote:
>>> The first part can be tested by holding the rear of the
>>> bike a foot off the ground, and using the other hand to
>>> pedal it up as fast as you can. Mine provides a definite
>>> up-and-down motion, which I experimentally corrected by
>>> balancing the wheel.
>>
>>THAT is an unrealistic test.
>
> What do you find unrealistic about it? Are you not strong
> enough to hold the rear of your bike up with one hand, and
> pedal it in a high gear with the other?
>
> That is a REAL, not just realistic, demonstration of a
> force found in a moving bicycle. It is a force that we
> choose to ignore, because it seems inconsequential; but if
> we're talking about high-precision rating of tire handling
> ability, it could make a difference, just as a bumpy road
> makes a difference in traction. The casing of the tire
> would affect how well it deals with the constant high
> frequency load-unload cycle.

It seems inconsequential precisely because it is. Have you
calculated the forces involved in this imbalance relative to
the vertical loading from your body weight? It'd be an
interesting mathematical problem- with the force resulting
from the imbalance being a tiny fraction of the mass of the
rider and bike.

This notion of imbalance as a "significant" issue comes from
cars, where the wheel is free to have a vertical excursion
thanks to the suspension and then only if the shock absorber
is worn to the point that it doesn't damp the wheel movement
correctly. A bicycle wheel cannot move freely in this manner
even in a fully suspended bike, because the forces probably
aren't high enough to overcome stiction. The forces are much
higher with a car wheel, which is turning several times
faster than a bicycle wheel and weighs 10 to 20 times more,
so there is much more inertial energy involved. When you
hold the bike up in the air and spin the wheel, you are
providing no damping.
 
R

Rick Onanian

Guest
On Tue, 22 Jun 2004 23:42:56 -0500, Tim McNamara
<[email protected]> wrote:
>Rick Onanian <[email protected]> writes:
>> it seems inconsequential; but if we're talking about high-
>> precision rating of tire handling ability, it could make
>> a difference, just as
>
>It seems inconsequential precisely because it is. Have you
>calculated the forces involved in this imbalance relative
>to the vertical loading from your body weight? It'd be an
>interesting mathematical problem- with the force resulting
>from the imbalance being a tiny fraction of the mass of the
>rider and bike.

I suspect the force in question is only a few pounds. It's
inconsequential for real-world riding, but not for _high-
precision_measurements_. We can either talk about real-world
handling, on roads whose imperceptibly imperfect surface
probably provides more reciprocating force than wheel
imbalance...or we can talk about measuring tire ability very
precisely. Or we can quit because, well, this discussion is
pointless... <G>
--
Rick Onanian
 
J

Jobst Brandt

Guest
Tim McNamara writes:

>>> I know what it is and have crashed as well as having
>>> measured it the test equipment I have described.

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

> I've seen it in crits. Is there a warning? No- it's pretty
> much instantaneous. Is it recoverable? Only by sheer luck.
> My personal experience was with being leaned way over in a
> crit and then striking a pedal, which lifted the rear
> tire. I didn't crash, but that had everything to do with
> luck and nothing to do with riding skills. Scared the hell
> out of the guy on my wheel.

Ah yes, but that does not rate as a break out from leaning
too far. 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.

Jobst Brandt [email protected]
 
B

Benjamin Weiner

Guest
[email protected] wrote:
> Tom Nakashima writes:

> > 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.

> > Is there a warning when you lean too far over in a turn
> > that would be unrecoverable and result in a crash.

> None at all, and when it starts going it is obvious.
> Judging from riders I pass down hills, few people ever get
> close to that point on dry pavement. On wet roads it
> occurs more often because the limit is so variable and is
> hard to assess.

> > Is it possible to recover if you have leaned too far
> > over in a turn?

> Not on dry pavement because there is nothing approaching
> that will increase traction at that lean angle... that is
> increasing rapidly as the slide progresses.

> > I'll have to say, you have a lot of guts to even attempt
> > this test. I could probably attempt this with full
> > leathers and a full face motorcycle helmet.

> I don't do such tests at speed. I ride below the limit,
> that is more than most riders are willing to approach
> because they haven't experienced the angle that is
> possible. It is also good to have seen tires on a testing
> machine exceed 45 degrees to have a feel for what is
> reasonable.

I think most riders are chary of approaching the limit of
lean angle, since it is difficult to judge when you are
approaching the limit and the penalty is obvious. As a
corollary, when people go into a turn too hot, I think they
usually instinctively take it too wide and cross the
centerline or go off the road, rather than increase lean and
low-side it. Ullrich went into the bushes that way in the
Tour a few years ago. That may be why one rarely sees people
low-siding on dry pavement.

A couple of my friends say they can take that first left
hand turn on Pescadero Road without any braking, but I'm too
chicken; it is a long way to ride home with road rash.
 
J

Jobst Brandt

Guest
Benjamin Weiner writes:

> I think most riders are wary of approaching the limit of
> lean angle, since it is difficult to judge when you are
> approaching the limit and the penalty is obvious. As a
> corollary, when people go into a turn too hot, I think
> they usually instinctively take it too wide and cross the
> centerline or go off the road, rather than increase lean
> and low-side it. Ullrich went into the bushes that way in
> the Tour a few years ago. That may be why one rarely sees
> people low-siding on dry pavement.

Some of that is because the idea that one should not brake
in a turn has been pounded into their heads. This is untrue
as I have explained and it is evident from anyone who is
cornering near the limit. They always are on the brakes in
the apex of the turn. The details of this are outlined in:

http://draco.acs.uci.edu/rbfaq/FAQ/9.15.html

and shown in:

http://tinyurl.com/2gbsj

> A couple of my friends say they can take that first left
> hand turn on Pescadero Road without any braking, but I'm
> too chicken; it is a long way to ride home with road rash.

That is the turn in the picture above and I do not take it
without braking. If they are doing that then they are not
going fast enough as they enter the curve. Of course that
also depends on how streamlined they are with respect to
their weight. I suspect I could take that corner without
braking if I was wearing a floppy jacket and didn't pedal on
the approach to the curve.

The second left hand curve also requires braking if you
are going fast, even though it has a larger radius. At
that point you should be going faster than in the previous
left hander.

Jobst Brandt [email protected]
 
T

Tim McNamara

Guest
[email protected] writes:

> Tim McNamara writes:
>
>>>> I know what it is and have crashed as well as having
>>>> measured it the test equipment I have described.
>
>>> Jobst, I have yet to see a cyclist crash or go down on
>>> DRY payment when leaning too far into a turn.
>
>> I've seen it in crits. Is there a warning? No- it's
>> pretty much instantaneous. Is it recoverable? Only by
>> sheer luck. My personal experience was with being leaned
>> way over in a crit and then striking a pedal, which
>> lifted the rear tire. I didn't crash, but that had
>> everything to do with luck and nothing to do with riding
>> skills. Scared the hell out of the guy on my wheel.
>
> Ah yes, but that does not rate as a break out from leaning
> too far.

Yes, that's true. I was a little OT there.

> 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.
 
J

Jobst Brandt

Guest
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 [email protected]
 
D

Dave Lehnen

Guest
[email protected] 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 [email protected]

Dave Lehnen
 
T

Tim McNamara

Guest
[email protected] 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.
 
T

Tom Nakashima

Guest
<[email protected]> wrote in message
news:[email protected]...
>
> > 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

G.Daniels

Guest
tire loss is directly related to: lack of $$ lack of tire
availability necessity to use cycle NOW answer-stock tires
 
G

G.Daniels

Guest
the ones with sand embedded cost more? what happened to
walnut shells?
 
S

S O R N I

Guest
g.daniels wrote:

> what happened to walnut shells?

Like you, they're cracked.

Bill "ty...tyvm" S.
 

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