Road tire life span



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.
 
C

carlfogel

Guest
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
 
J

Jobst Brandt

Guest
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]
 
J

Jobst Brandt

Guest
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]
 
C

carlfogel

Guest
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.
 
J

Jobst Brandt

Guest
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
 
J

Jobst Brandt

Guest
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
 
J

Jobst Brandt

Guest
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]
 
C

carlfogel

Guest
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
 
J

Jobst Brandt

Guest
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]
 
J

Jobst Brandt

Guest
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]
 
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
 
C

carlfogel

Guest
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
 
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
 
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
 
H

Hjalmar DuklæT

Guest
> Hutchinson Carbon Comp tires. They wear very well, but
> still have good
fast
> cornering characteristics (I use em in crits, but I'm only
> Cat 4, so we're not cornering at 30+) and pliable enough
> (even at 140PSI) that on long rides, I don't start cursing
> them out.

I also use Hutchinson Carbon Comp tires on my competition
wheels. They have been on for nearly three seasons now and
probably run about 1500 miles. I've not had any flats so far
(knock on wood) besides the one I made when I put them on
for the first time (quite tight fit on Shimano wheels).
These are the only clinchers I've used so cannot say
anything about other brands. By the way I got a flat on my
front tubular this morning. A real bang going at 35 mph.
Luckily the glue kept it on. Hjalmar
 

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