Road tire life span



On Fri, 18 Jun 2004 22:58:22 GMT,
[email protected] wrote:

>Carl Fogel writes:
>
>>>> It's too bad as the Open Corsas have typically been the nicest
>>>> handling tires I've used, but they go away so quickly and they're
>>>> so expensive that I'm looking for something else.

>
>>> How do you [know] whether one tire handles better than another
>>> since traction is either there or not on pavement. There is no
>>> tire squeal or side-slip, although writers to this newsgroup
>>> sometimes describe their cornering as drifting in curves. This
>>> does not occur. Besides that, chip seal, the most abrasive, roads
>>> have poorer traction than concrete or hot-mix asphalt roads.

>
>> Maybe Tom notices that the traction is "not there" on the
>> pavement more often with poorer handling tires?

>
>Maybe shmaybe, let the man speak for himself. You don't have to hold
>his hand.
>
>> It seems unlikely, but are you saying that no rider can tell whether
>> one tire handles better than another in terms of traction?

>
>Unless it is a knobby tire (not a road tire of the kind in question)
>there is no perceptible difference in handling until is washes out in
>a curve, something that occurs with colored tires on wet roads. It is
>not something you prefer to test but it has been done both in situ and
>on the tire testing machine I once designed for Avocet to measure
>maximum lean angle for tires.
>
>> Since you offer no answer, your hastily typed question "How
>> do you [?] whether one tire handles better than another . .
>> ." seems rhetorical.

>
>That may be so in your estimation but I didn't ask you.
>
>> So how do you tell if one tire handles better than another?

>
>You test it on a machine. I originally performed such tests on a 16ft
>long paved plywood tiltbed increasing the angle until the bicycle
>slid. This was done at low speed and with protective clothing. There
>was a difference among tires tested. That was a few years ago.
>
>Jobst Brandt
>[email protected]umni.org


Dear Jobst,

If you don't like people replying to your posts, a newsgroup
may not be the best place to spend your time.

So your position is that no rider can tell the difference
between the way different tires handle during normal riding
and that they can be distinguished only at low speed on a
machine.

Thanks,

Carl Fogel
 
C

cheg

Guest

> >> So how do you tell if one tire handles better than another?

> >
> >You test it on a machine. I originally performed such tests on a 16ft
> >long paved plywood tiltbed increasing the angle until the bicycle
> >slid. This was done at low speed and with protective clothing. There
> >was a difference among tires tested. That was a few years ago.
> >
> >Jobst Brandt
> >[email protected]

>
> Dear Jobst,
>
> If you don't like people replying to your posts, a newsgroup
> may not be the best place to spend your time.
>
> So your position is that no rider can tell the difference
> between the way different tires handle during normal riding
> and that they can be distinguished only at low speed on a
> machine.
>
> Thanks,
>
> Carl Fogel


Perhaps you should both start by defining "handle" in this context. If it is
strictly lateral load bearing capacity while rolling, then direct measurement
would be the way to go. If it includes other characteristics, eg. vibration
transmssion, then the measurement is not sufficient by itself.
 
On Sat, 19 Jun 2004 00:33:21 GMT, "cheg"
<[email protected]> wrote:

>
>> >> So how do you tell if one tire handles better than another?
>> >
>> >You test it on a machine. I originally performed such tests on a 16ft
>> >long paved plywood tiltbed increasing the angle until the bicycle
>> >slid. This was done at low speed and with protective clothing. There
>> >was a difference among tires tested. That was a few years ago.
>> >
>> >Jobst Brandt
>> >[email protected]

>>
>> Dear Jobst,
>>
>> If you don't like people replying to your posts, a newsgroup
>> may not be the best place to spend your time.
>>
>> So your position is that no rider can tell the difference
>> between the way different tires handle during normal riding
>> and that they can be distinguished only at low speed on a
>> machine.
>>
>> Thanks,
>>
>> Carl Fogel

>
>Perhaps you should both start by defining "handle" in this context. If it is
>strictly lateral load bearing capacity while rolling, then direct measurement
>would be the way to go. If it includes other characteristics, eg. vibration
>transmssion, then the measurement is not sufficient by itself.
>


Dear Cheg,

Yes, handling is probably many faceted.

A tire that stops well in a straight line on dry pavement,
for example, might not corner as well due to profile or
carcass design. Inflation alone varies so much in bicycle
tires that it may obscure all sorts of differences.

From what I see of Consumer Reports testing of car tires,
handling often varies between brands according to wet or dry
and between braking and cornering. They also do their best
to poll testers about less easily quantified characteristics
as "harshness," which I expect is what you have in mind with
vibration.

Unfortunately, tire handling for bicycles and motorcycles is
hard to test, since what would be a mere skid for a car is
likely to be a crash on two wheels and better riders may be
able to do more with the same equipment. That is,
practically anyone can crank a car on a skid pad up to a
certain speed and see whether it can stay on the curving
line, but riders on only two wheels need considerably more
confidence and skill to do the same thing at normal speeds
and higher.

I'm curious about bicycle tires and handling for two
reasons.

First, I know very little about it--my daily ride involves
neither high-speed cornering nor exciting stops.

Second, I have a vague suspicion that handling is relatively
unimportant in typical road competition. I sometimes wonder
whether bulldozer races place equal emphasis on cornering.

The Tour de France, for example, consists of rigid-frame
vehicles riding mostly in cooperative packs on pavement at
25-30 mph and sometimes up mountains alone at much lower
speeds. After three weeks, only a few minutes separate first
and second place. I doubt that anyone is going to whip Lance
Armstrong by mounting better-handling tires, but I'm willing
to learn otherwise.

Carl Fogel
 
Carl Fogel writes:

> If you don't like people replying to your posts, a newsgroup may not
> be the best place to spend your time.


Your interpretation of discourse here is trying hard to
mis-characterize what is said.

> So your position is that no rider can tell the difference between
> the way different tires handle during normal riding and that they
> can be distinguished only at low speed on a machine.


That is not what I said. You can test the wipe-out angle of tires at
speed but that is both painful and destructive to the bicyclist. An
alternative is to use a test bed and since speed is not a ruling
parameter, it can and has been be done at low speeds. I have done
that.

The point I tried to bring across is that road tires don't squeal or
slid on pavement until they have a sudden and unrecoverable breakout.
Therefore the question remains, how dose one arrive at the assessment
that a tire handles well.

I think that is a valid and simple question and it was not aimed at
you although if you have the answer I would like to hear it.

Jobst Brandt
[email protected]
 
Cheg Nospam writes:

>>>> So how do you tell if one tire handles better than another?


>>> You test it on a machine. I originally performed such tests on a
>>> 16ft long paved plywood tiltbed increasing the angle until the
>>> bicycle slid. This was done at low speed and with protective
>>> clothing. There was a difference among tires tested. That was a
>>> few years ago.


>> If you don't like people replying to your posts, a newsgroup may
>> not be the best place to spend your time.


>> So your position is that no rider can tell the difference between
>> the way different tires handle during normal riding and that they
>> can be distinguished only at low speed on a machine.


> Perhaps you should both start by defining "handle" in this
> context. If it is strictly lateral load bearing capacity while
> rolling, then direct measurement would be the way to go. If it
> includes other characteristics, eg. vibration transmssion, then the
> measurement is not sufficient by itself.


The term "handling" is adequately defined by use in the tire business
and it concerns itself with maneuverability in cornering and for cars
how well the tire tracks straight ahead. Ride comfort is another matter.


Jobst Brandt
[email protected]
 
On Sat, 19 Jun 2004 02:40:43 GMT,
[email protected] wrote:

>Carl Fogel writes:
>
>> If you don't like people replying to your posts, a newsgroup may not
>> be the best place to spend your time.

>
>Your interpretation of discourse here is trying hard to
>mis-characterize what is said.
>
>> So your position is that no rider can tell the difference between
>> the way different tires handle during normal riding and that they
>> can be distinguished only at low speed on a machine.

>
>That is not what I said. You can test the wipe-out angle of tires at
>speed but that is both painful and destructive to the bicyclist. An
>alternative is to use a test bed and since speed is not a ruling
>parameter, it can and has been be done at low speeds. I have done
>that.
>
>The point I tried to bring across is that road tires don't squeal or
>slid on pavement until they have a sudden and unrecoverable breakout.
>Therefore the question remains, how dose one arrive at the assessment
>that a tire handles well.
>
>I think that is a valid and simple question and it was not aimed at
>you although if you have the answer I would like to hear it.
>
>Jobst Brandt
>[email protected]


Dear Jobst,

So your position is that no rider can tell the difference
between the way different tires handle during normal riding
and that they an be distinguished--

--without pain and destruction--

--only at low speed on a test bed.

I think that is a valid and simple statement of what you
were actually saying to the original poster. I'm not arguing
with you, just trying to see what your position is.

Thanks,

Carl Fogel
 
C

cheg

Guest
<[email protected]> wrote in message
news:[email protected]
> Cheg Nospam writes:
>
>
> The term "handling" is adequately defined by use in the tire business
> and it concerns itself with maneuverability in cornering and for cars
> how well the tire tracks straight ahead. Ride comfort is another matter.
>
>


Seems like it would be more clear to call it "cornering traction" or something
like that for tires. Handling applied to vehicles is much more complex,
dependent on weight distribution, stiffness, steering geometry, drag, etc., as
well as traction. Can't do much about traditional usage, I guess.
 
Cheg Nospam writes:

>> The term "handling" is adequately defined by use in the tire
>> business and it concerns itself with maneuverability in cornering
>> and for cars how well the tire tracks straight ahead. Ride comfort
>> is another matter.


> Seems like it would be more clear to call it "cornering traction" or
> something like that for tires. Handling applied to vehicles is much
> more complex, dependent on weight distribution, stiffness, steering
> geometry, drag, etc., as well as traction. Can't do much about
> traditional usage, I guess.


TIRES! Not vehicles. This is about tires and that is extra simple
for road bicycle tires. Hnadling being how well the tire performs in
curves, nothing more.

Jobst Brandt
[email protected]
 
R

Rick Onanian

Guest
On Fri, 18 Jun 2004 22:31:38 GMT, [email protected]
wrote:
>How do you whether one tire handles better than another since traction
>is either there or not on pavement. There is no tire squeal or
>side-slip although writers to this newsgroup sometimes describe their
>cornering as drifting in curves. This does not occur. Besides that,
>chip seal, the most abrasive, roads have poorer traction than concrete
>or hot-mix asphalt roads.


This may be all true in a perfect world where roads are fresh, clean
pavement. I, however, experienced a controllable side-slip on my
rear tire, followed by whole-bike drift, while doing some 35 mph
downhill, around a curve, on an older road whose pavement is
probably imperfect (probably not as flat a surface as a taut string,
for example), and it was probably not perfectly clean.

I was kinda zoned out, pedalling with all my might, when I felt it,
and before I processed that information, I found I was on the wrong
side of the road; slowing down brought back the missing traction. No
accident resulted, but I did get quite scared.

It was very exciting, and if I thought I could purposely duplicate
it without an accident, I'd love to.

In a later message, Jobst wrote:
>You test it on a machine. I originally performed such tests on a 16ft
>long paved plywood tiltbed increasing the angle until the bicycle
>slid.


I suspect that the different compounds, as well as tire casing
constructions, react differently to the changing conditions of a
road while moving than to the static conditions of a stopped bicycle
on a tilted platform. Per my example above, where I theorize that
the pavement is probably slightly wavy (although I've never noticed
it, a tire on a 35 mph bike would), the tire's casing would have
quite an effect on how the tire's tread stays in contact with the
road.

The casing also must compensate for imbalanced wheels. We don't
balance our wheels because it doesn't bother us; but if you lift
your bike, hold it in your hand, and pedal the rear wheel up to 25
mph, you may feel the bike jumping up and down. Mine does; I taped
weights to the wheel until it was balanced, just to see if I could.
I suppose it could be something odd with the bearings...

Additionally, that test is certainly irrelevant for lateral
traction; it only tests fore-aft traction. Sideways, the tire bends
(again, involving the casing), and also the rider leans, exposing a
different part of the tire to the road.

Later still, Jobst wrote:
>TIRES! Not vehicles. This is about tires and that is extra simple
>for road bicycle tires. Hnadling being how well the tire performs in
>curves, nothing more.


Then what makes you think your tilt-brake-slide test is relevant to
this thread?

Then, Carl did his best to determine what Jobst is trying to say:
> So your position is that no rider can tell the difference
>between the way different tires handle during normal riding
>and that they an be distinguished--
>--without pain and destruction--
>--only at low speed on a test bed.


If, in fact, that is a correct translation, then I disagree that a
rider can't tell; and more importantly, if I'm wrong and the only
way to know how a tire handles is to wipe out, then it would seem
_very_ important to know how the tire handles before buying it; at
that point, one's life could depend on a tire's handling ability.
--
Rick Onanian
 
Rick Onanian writes:

>> How do you whether one tire handles better than another since
>> traction is either there or not on pavement. There is no tire
>> squeal or side-slip although writers to this newsgroup sometimes
>> describe their cornering as drifting in curves. This does not
>> occur. Besides that, chip seal, the most abrasive, roads have
>> poorer traction than concrete or hot-mix asphalt roads.


> This may be all true in a perfect world where roads are fresh, clean
> pavement. I, however, experienced a controllable side-slip on my
> rear tire, followed by whole-bike drift, while doing some 35 mph
> downhill, around a curve, on an older road whose pavement is
> probably imperfect (probably not as flat a surface as a taut string,
> for example), and it was probably not perfectly clean.


If it was pavement with no sand or other solid (lubricant) I am
reasonably sure that you did not drift around a curve on pavement.
None of the best bicycle riders in this area believe that this is
possible either nor does the tire testing machine that displays sudden
and irrecoverable break out while determining maximum lean angle.

> I was kinda zoned out, pedalling with all my might, when I felt it,
> and before I processed that information, I found I was on the wrong
> side of the road; slowing down brought back the missing traction. No
> accident resulted, but I did get quite scared.


I am sure you experienced loss of traction but it was not on clean dry
pavement, that condition where cornering ability of a tire can only be
assessed by measurement at the moment of break out and crashing. That
is not a reasonable thing to attempt and that is why I asked how
handling of one tire over another under similar conditions is
assessed.

> It was very exciting, and if I thought I could purposely duplicate
> it without an accident, I'd love to.


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.

> In a later message, Jobst wrote:


>> You test it on a machine. I originally performed such tests on a
>> 16ft long paved plywood tiltbed increasing the angle until the
>> bicycle slid.


> I suspect that the different compounds, as well as tire casing
> constructions, react differently to the changing conditions of a
> road while moving than to the static conditions of a stopped bicycle
> on a tilted platform. Per my example above, where I theorize that
> the pavement is probably slightly wavy (although I've never noticed
> it, a tire on a 35 mph bike would), the tire's casing would have
> quite an effect on how the tire's tread stays in contact with the
> road.


Who's talking about static condition? The test bed was ridden across
at about 15mph. That is dynamic enough to give a reading and to
differentiate between slick tires of that time and ones with a raised
center ridge. Bicycle tires do not generate enough heat to have any
effect on traction. If they did, you would be able to feel it after
making a hard stop from, say, 30mph on a flat road. That is more work
than a tire does when cornering because all the weight is on the front
wheel and the retardation is close to that of hard cornering.

> The casing also must compensate for imbalanced wheels. We don't
> balance our wheels because it doesn't bother us; but if you lift
> your bike, hold it in your hand, and pedal the rear wheel up to 25
> mph, you may feel the bike jumping up and down. Mine does; I taped
> weights to the wheel until it was balanced, just to see if I could.
> I suppose it could be something odd with the bearings...


I guess you missed the balance experiments that were done by placing
lead weights at one spoke location and other such balance and
imbalance conditions that are used as excuses for all sorts of rider
errors. This has all been done. None of the best descenders I have
talked to has ever considered balanced tires as a benefit.

> Additionally, that test is certainly irrelevant for lateral
> traction; it only tests fore-aft traction. Sideways, the tire bends
> (again, involving the casing), and also the rider leans, exposing a
> different part of the tire to the road.


I think you are not visualizing what occurs when a bicycle leans in a
curve. The tire testing machine leaned the tire that was loaded
in-plane onto a large paved drum while a set of sensors triggered the
recording of the angle at which the wheel slipped out. This was
repeatable and was done at about 20mph. There are no side loads any
more than there are side loads on a bicycle when cornering.

> Later still, Jobst wrote:


>> TIRES! Not vehicles. This is about tires and that is extra simple
>> for road bicycle tires. Handling being how well the tire performs
>> in curves, nothing more.


> Then what makes you think your tilt-brake-slide test is relevant to
> this thread?


The test was cornering and that alone and was repeatable. Even though
the in situ test at 40mph was made, the limit was not exceeded:

http://tinyurl.com/2gbsj

> Then, Carl did his best to determine what Jobst is trying to say:
>> So your position is that no rider can tell the difference
>> between the way different tires handle during normal riding
>> and that they an be distinguished--
>> --without pain and destruction--
>> --only at low speed on a test bed.


> If, in fact, that is a correct translation, then I disagree


I disagree also because that is not a correct translation. In a
subsequent reply I reiterated what I said and meant. Maybe you can
take that up and tell me how you assess the handling differences
between similar sized tires of different manufacture under similar
conditions. By this I do not mean a singular anecdote in which a
certain tire did thus and so with no comparison.

> I disagree that a rider can't tell; and more importantly, if I'm
> wrong and the only way to know how a tire handles is to wipe out,
> then it would seem _very_ important to know how the tire handles
> before buying it; at that point, one's life could depend on a tire's
> handling ability.


Could you explain what this paragraph means with respect to a rider
being able to feel that one tire handles better than another? My
statement is that since road tires (without knobs) do not have a
transition point on smooth dry pavement, riders who claim that a tire
handles well are merely repeating advertising copy, because below the
slip out limit (the only difference) no difference in handling is
noticeable. Again, handling being control in curves.

Jobst Brandt
[email protected]
 
R

Rick Onanian

Guest
On Sun, 20 Jun 2004 00:43:09 GMT, [email protected]
wrote:
>Rick Onanian writes:
>> This may be all true in a perfect world where roads are fresh, clean
>> pavement. I, however, experienced a controllable side-slip on my
>> rear tire, followed by whole-bike drift, while doing some 35 mph
>> downhill, around a curve, on an older road whose pavement is
>> probably imperfect (probably not as flat a surface as a taut string,
>> for example), and it was probably not perfectly clean.

>
>If it was pavement with no sand or other solid (lubricant) I am
>reasonably sure that you did not drift around a curve on pavement.


It probably was not perfect, fresh, clean, 100% black, unmolested
pavement. I'm sure that it includes some dust and dirt. Many
driveways on that street are dirt. No dirt was visible on the
pavement, but it wasn't the 100% dark jet black of brand new
pavement either.

In short, it's a real world condition.

>I am sure you experienced loss of traction but it was not on clean dry
>pavement, that condition where cornering ability of a tire can only be
>assessed by measurement at the moment of break out and crashing. That


Agreed. It was a real road, the kind where bicyclists depend on tire
traction.

>is not a reasonable thing to attempt and that is why I asked how
>handling of one tire over another under similar conditions is
>assessed.


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.

>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.

>>> You test it on a machine. I originally performed such tests on a
>>> 16ft long paved plywood tiltbed increasing the angle until the
>>> bicycle slid.

>
>> I suspect that the different compounds, as well as tire casing
>> constructions, react differently to the changing conditions of a
>> road while moving than to the static conditions of a stopped bicycle
>> on a tilted platform. Per my example above, where I theorize that
>> the pavement is probably slightly wavy (although I've never noticed
>> it, a tire on a 35 mph bike would), the tire's casing would have
>> quite an effect on how the tire's tread stays in contact with the
>> road.

>
>Who's talking about static condition? The test bed was ridden across
>at about 15mph. That is dynamic enough to give a reading and to


I think I understand; the bed was tilted sideways while you rode
across it, leaning to the high side of the bed to keep yourself
plumb. That makes more sense; I visualized you on the non-moving
bike holding the brakes as the front of the bed raised (in a dumping
motion), until the bike slid.

>> The casing also must compensate for imbalanced wheels. We don't
>> balance our wheels because it doesn't bother us; but if you lift
>> your bike, hold it in your hand, and pedal the rear wheel up to 25
>> mph, you may feel the bike jumping up and down. Mine does; I taped
>> weights to the wheel until it was balanced, just to see if I could.
>> I suppose it could be something odd with the bearings...

>
>I guess you missed the balance experiments that were done by placing
>lead weights at one spoke location and other such balance and
>imbalance conditions that are used as excuses for all sorts of rider
>errors. This has all been done. None of the best descenders I have
>talked to has ever considered balanced tires as a benefit.


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.

>> Additionally, that test is certainly irrelevant for lateral
>> traction; it only tests fore-aft traction. Sideways, the tire bends
>> (again, involving the casing), and also the rider leans, exposing a
>> different part of the tire to the road.

>
>I think you are not visualizing what occurs when a bicycle leans in a
>curve. The tire testing machine leaned the tire that was loaded
>in-plane onto a large paved drum while a set of sensors triggered the
>recording of the angle at which the wheel slipped out. This was
>repeatable and was done at about 20mph. There are no side loads any
>more than there are side loads on a bicycle when cornering.


A different portion of the tread, supported differently by the
sidewalls, is in contact with the road. However, the tire testing
machine of which you speak, and of which I was unaware in my
previous message, would test that.

>> I disagree that a rider can't tell; and more importantly, if I'm
>> wrong and the only way to know how a tire handles is to wipe out,
>> then it would seem _very_ important to know how the tire handles
>> before buying it; at that point, one's life could depend on a tire's
>> handling ability.

>
>Could you explain what this paragraph means with respect to a rider
>being able to feel that one tire handles better than another? My


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

More importantly, however, you've failed to address the big issue --
if tires really do break out without any warning as you say, then it
would seem extremely important to be able to choose a tire based on
it's actual tested and reviewed handling. A high speed traction
failure accident sure sounds dangerous! I doubt I would have ridden
home if my slip incident turned into a complete loss of control; at
35 mph or so, I would have wrapped my body around a tree or a stone
wall (the two types of object found on the side of that road).
--
Rick Onanian
 
Rick Onanian writes:

>>> This may be all true in a perfect world where roads are fresh, clean
>>> pavement. I, however, experienced a controllable side-slip on my
>>> rear tire, followed by whole-bike drift, while doing some 35 mph
>>> downhill, around a curve, on an older road whose pavement is
>>> probably imperfect (probably not as flat a surface as a taut string,
>>> for example), and it was probably not perfectly clean.


>> If it was pavement with no sand or other solid (lubricant) I am
>> reasonably sure that you did not drift around a curve on pavement.


> It probably was not perfect, fresh, clean, 100% black, unmolested
> pavement. I'm sure that it includes some dust and dirt. Many
> driveways on that street are dirt. No dirt was visible on the
> pavement, but it wasn't the 100% dark jet black of brand new
> pavement either.


I'm not quibbling about common dust on roads. The dry pavement you
describe fits the definition of clean dry pavement and on such a
surface, no "drifting" or sliding is possible without crashing. This
has been measured often enough and we have not seen anyone who can
demonstrate a slide in a curve since the lean angle for that is
greater than 45 degrees to the pavement. At that angle, no one I or
any of the fastest descenders that I know have seen anyone do that and
not crash.

> In short, it's a real world condition.


It doesn't take that much definition.

>> I am sure you experienced loss of traction but it was not on clean
>> dry pavement, that condition where cornering ability of a tire can
>> only be assessed by measurement at the moment of break out and
>> crashing.


> Agreed. It was a real road, the kind where bicyclists depend on tire
> traction.


>> That is not a reasonable thing to attempt and that is why I asked
>> how handling of one tire over another under similar conditions is
>> assessed.


> 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. We have a
few riders in this area who corner at the limit of near 45 degrees and
the testing machine predicts break out at 47 or so with slick tread
repeatably.

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

>>>> You test it on a machine. I originally performed such tests on a
>>>> 16ft long paved plywood tiltbed increasing the angle until the
>>>> bicycle slid.


>>> I suspect that the different compounds, as well as tire casing
>>> constructions, react differently to the changing conditions of a
>>> road while moving than to the static conditions of a stopped
>>> bicycle on a tilted platform. Per my example above, where I
>>> theorize that the pavement is probably slightly wavy (although
>>> I've never noticed it, a tire on a 35 mph bike would), the tire's
>>> casing would have quite an effect on how the tire's tread stays in
>>> contact with the road.


>> Who's talking about static condition? The test bed was ridden across
>> at about 15mph. That is dynamic enough to give a reading and to


> I think I understand; the bed was tilted sideways while you rode
> across it, leaning to the high side of the bed to keep yourself
> plumb. That makes more sense; I visualized you on the non-moving
> bike holding the brakes as the front of the bed raised (in a dumping
> motion), until the bike slid.


I didn't lean, I rode across it upright. The test bed was tilted.
When the tilt was too steep, the bicycle slid out unrecoverably as it
does on a road.

>>> The casing also must compensate for imbalanced wheels. We don't
>>> balance our wheels because it doesn't bother us; but if you lift
>>> your bike, hold it in your hand, and pedal the rear wheel up to 25
>>> mph, you may feel the bike jumping up and down. Mine does; I
>>> taped weights to the wheel until it was balanced, just to see if I
>>> could. I suppose it could be something odd with the bearings...


>> I guess you missed the balance experiments that were done by
>> placing lead weights at one spoke location and other such balance
>> and imbalance conditions that are used as excuses for all sorts of
>> rider errors. This has all been done. None of the best descenders
>> I have talked to has ever considered balanced tires as a benefit.


> 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. 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
said, I have done balance and imbalance tests with no perceptible
effect and reported the results here. These tests were done to prove
that shimmy is not related to wheel im/balance.

>>> Additionally, that test is certainly irrelevant for lateral
>>> traction; it only tests fore-aft traction. Sideways, the tire
>>> bends (again, involving the casing), and also the rider leans,
>>> exposing a different part of the tire to the road.


>> I think you are not visualizing what occurs when a bicycle leans in
>> a curve. The tire testing machine leaned the tire that was loaded
>> in-plane onto a large paved drum while a set of sensors triggered
>> the recording of the angle at which the wheel slipped out. This
>> was repeatable and was done at about 20mph. There are no side
>> loads any more than there are side loads on a bicycle when
>> cornering.


> A different portion of the tread, supported differently by the
> sidewalls, is in contact with the road. However, the tire testing
> machine of which you speak, and of which I was unaware in my
> previous message, would test that.


I don't understand what you propose here. The tires tested were
typical of available major brand tires.

>>> I disagree that a rider can't tell; and more importantly, if I'm
>>> wrong and the only way to know how a tire handles is to wipe out,
>>> then it would seem _very_ important to know how the tire handles
>>> before buying it; at that point, one's life could depend on a
>>> tire's handling ability.


>> Could you explain what this paragraph means with respect to a rider
>> being able to feel that one tire handles better than another?


> 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.

> More importantly, however, you've failed to address the big issue --
> if tires really do break out without any warning as you say, then it
> would seem extremely important to be able to choose a tire based on
> it's actual tested and reviewed handling. A high speed traction
> failure accident sure sounds dangerous! I doubt I would have ridden
> home if my slip incident turned into a complete loss of control; at
> 35 mph or so, I would have wrapped my body around a tree or a stone
> wall (the two types of object found on the side of that road). --


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.

Tire testing machinery is important in this business and as far as I
can tell no one has one other than Avocet, a company that is not
currently performing such tests.

Jobst Brandt
[email protected]
 
R

Rick Onanian

Guest
On Tue, 22 Jun 2004 01:33:44 GMT, [email protected]
wrote:
>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. We have a


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 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.

>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.

>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.

>> 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?

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.

> 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 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.
--
Rick Onanian
 
On Tue, 22 Jun 2004 01:33:44 GMT,
[email protected] wrote:

[snip]

>
>Tire testing machinery is important in this business and as far as I
>can tell no one has one other than Avocet, a company that is not
>currently performing such tests.
>
>Jobst Brandt
>[email protected]


Dear Jobst,

While most of what you wrote makes sense, your closing
sentence puzzles me.

If "tire testing machinery is important in this business,"
why does only one company have it--and not currently use it?

When you wrote "business," did you perhaps mean the topic of
the thread and not the actual business of the Avocet
company?

Carl Fogel
 
B

Benjamin Lewis

Guest
[email protected] wrote:

> [email protected] wrote:
>
>> Tire testing machinery is important in this business and as far as I
>> can tell no one has one other than Avocet, a company that is not
>> currently performing such tests.

>
> While most of what you wrote makes sense, your closing
> sentence puzzles me.
>
> If "tire testing machinery is important in this business,"
> why does only one company have it--and not currently use it?


Is there a difference between "should be important" and "is important"?
(Not a rhetorical question. I think it depends on how you define
"important".)

--
Benjamin Lewis

I regret to say that we of the FBI are powerless to act in cases of
oral-genital intimacy, unless it has in some way obstructed interstate
commerce. -- J. Edgar Hoover
 
Carl Fogel writes:

>> Tire testing machinery is important in this business and as far as
>> I can tell no one has one other than Avocet, a company that is not
>> currently performing such tests.


> While most of what you wrote makes sense, your closing sentence
> puzzles me.


> If "tire testing machinery is important in this business," why does
> only one company have it--and not currently use it?


Because I don't work for these companies and designed the machine for
Avocet at a time when I encouraged them to introduce slick tread
tires. Their question was, "how can we convince people they won't
crash with them?"

http://tinyurl.com/2gbsj

My response was the test bed and the machine, plus the picture of the
tire in action. You apparently don't recall how extreme the
resistance to smooth tread was at the time. We may have gotten over
that now but it could always return if Continental, for instance, put
on a big advertising effort to sell a new tread pattern. People
forget.

> When you wrote "business," did you perhaps mean the topic of the
> thread and not the actual business of the Avocet company?


What means this? Please clarify.

Jobst Brandt
[email protected]
 
Benjamin Lewis writes:

>>> Tire testing machinery is important in this business and as far as
>>> I can tell no one has one other than Avocet, a company that is not
>>> currently performing such tests.


>> While most of what you wrote makes sense, your closing sentence
>> puzzles me.


>> If "tire testing machinery is important in this business," why does
>> only one company have it--and not currently use it?


> Is there a difference between "should be important" and "is
> important"? (Not a rhetorical question. I think it depends on how
> you define "important".)


That depends on whether you think traction is an important parameter.
Currently, those who make colored treads do not think so or they
wouldn't send people out in wet weather on their tires. A quick run
on a testing machine would reveal how these tire track in wet and dry
in short order and they could be compared against some standard carbon
black tread tire.

That for me falls into the definition "is important". How can this
not be important to a tire manufacturer?

Jobst Brandt
[email protected]
 
On Tue, 22 Jun 2004 03:44:40 GMT,
[email protected] wrote:

>Carl Fogel writes:
>
>>> Tire testing machinery is important in this business and as far as
>>> I can tell no one has one other than Avocet, a company that is not
>>> currently performing such tests.

>
>> While most of what you wrote makes sense, your closing sentence
>> puzzles me.

>
>> If "tire testing machinery is important in this business," why does
>> only one company have it--and not currently use it?

>
>Because I don't work for these companies and designed the machine for
>Avocet at a time when I encouraged them to introduce slick tread
>tires. Their question was, "how can we convince people they won't
>crash with them?"
>
>http://tinyurl.com/2gbsj
>
>My response was the test bed and the machine, plus the picture of the
>tire in action. You apparently don't recall how extreme the
>resistance to smooth tread was at the time. We may have gotten over
>that now but it could always return if Continental, for instance, put
>on a big advertising effort to sell a new tread pattern. People
>forget.
>
>> When you wrote "business," did you perhaps mean the topic of the
>> thread and not the actual business of the Avocet company?

>
>What means this? Please clarify.
>
>Jobst Brandt
>[email protected]


Dear Jobst,

I was just trying to figure out why you seemed to be saying
that tire testing machinery is important in this [tire
manufacturing?] business, but then apparently saying that
only one company thinks that it's important enough to have
such machinery and isn't even using it at present.

This seems to be the familiar picture of you in a corner:

http://tinyurl.com/2gbsj

Are there any pictures of the machine in use?

Thanks,

Carl Fogel
 
B

Benjamin Lewis

Guest
jobst brandt wrote:

> Benjamin Lewis writes:
>
>> Is there a difference between "should be important" and "is
>> important"? (Not a rhetorical question. I think it depends on how
>> you define "important".)

>
> That depends on whether you think traction is an important parameter.
> Currently, those who make colored treads do not think so or they
> wouldn't send people out in wet weather on their tires. A quick run
> on a testing machine would reveal how these tire track in wet and dry
> in short order and they could be compared against some standard carbon
> black tread tire.
>
> That for me falls into the definition "is important". How can this
> not be important to a tire manufacturer?


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?

--
Benjamin Lewis

I regret to say that we of the FBI are powerless to act in cases of
oral-genital intimacy, unless it has in some way obstructed interstate
commerce. -- J. Edgar Hoover
 
H

Helmut Springer

Guest
[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-/

--
MfG/Best regards
helmut springer
 

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