slicks vs treads
Jobst Brandt
Ken Kifer writes:
> Someone else has objected to the word "hydroplaning"; let's just use
> slipping or sliding instead. I only once noticed a problem with a
> slick tire. I was on a smooth highway on a wet day, and I almost
> lost control from a fresh paint stripe. Traction was zero for an
> instant.
As I have often pointed out. There is no tire that will give traction
on a slick surface such as a paint stripe, manhole cover, railroad
track or any smooth homogeneous material with a water film on it. It
takes micro grit to penetrate the lubricating water layer.
You can test this by running a squeegee over a wet car window on a
sunny day and see the difference between wet and the second swipe when
it is dry. A rubber Squeegee has the sharpest rubber tread edge
available and it glides effortlessly over wet glass. Boundary layers
are not easily removed and a tire tread does a lot worse job than a
squeegee.
If this example does not demonstrate how strong boundary layers are,
you might consider the razor blade that does not penetrate the
boundary layer of water on your skin when you shave. If you dry your
skin with alcohol, allowing it to evaporate, a sharp blade will cut
the skin. The argument that a slick tire caused a slip on a railroad
track is like saying the slick caused you to fall on ice.
Jobst Brandt <jbr...@hpl.hp.com>
hau...@mbi.org
In article <5ldob7$h...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst Brandt) writes:
>From: jbr...@hpl.hp.com (Jobst Brandt)
>Subject: Re: slicks vs treads
>Date: 15 May 1997 01:19:35 GMT
>Ken Kifer writes:
>> Someone else has objected to the word "hydroplaning"; let's just use
>> slipping or sliding instead. I only once noticed a problem with a
>> slick tire. I was on a smooth highway on a wet day, and I almost
>> lost control from a fresh paint stripe. Traction was zero for an
>> instant.
>As I have often pointed out. There is no tire that will give traction
>on a slick surface such as a paint stripe, manhole cover, railroad
>track or any smooth homogeneous material with a water film on it. It
>takes micro grit to penetrate the lubricating water layer.
Unfortunately, those who have responded in support of slicks on wet pavement
have done so from a theoretical point of view. Armchair theories are one
thing, but this thread is becoming similar to the 'brains on road' thread in
that actual real-life experiences are being discounted to the point that they
must not have existed, since they discredit the theories being spewed forth.
I've ridden slicks under the same conditions as treaded with more slipping in
the wet; others have reported similar happenings. Further, I've found that
slicks cut easier, which I would assume is due to softer rubber. How would
you explain it, Jobst? Your assumption that all bicycle tires use the same
hardness of rubber is an awfully big one!
It's certainly possible I just didn't happen to use good slicks. I used two
different brands, but not the beloved Avocets Jobst recommends. Of course,
for what they cost, Avocets certainly SHOULD be superior. What model do you
recommend, Jobst?
Although I usually use Conti's, I don't put much stock in
manufacturer-sponsored 'tests'. Thus, that data isn't terribly useful.
>If this example does not demonstrate how strong boundary layers are,
>you might consider the razor blade that does not penetrate the
>boundary layer of water on your skin when you shave. If you dry your
>skin with alcohol, allowing it to evaporate, a sharp blade will cut
>the skin. The argument that a slick tire caused a slip on a railroad
>track is like saying the slick caused you to fall on ice.
Well, then, I guess we'd better stop driving our cars around in the rain. As
Jobst has pointed out, it's virtually impossible to cut through the 'boundary
layer' to obtain traction - even a razor blade can't!
Rich
Dr. David Martin
hau...@mbi.org wrote:
> Unfortunately, those who have responded in support of slicks on wet pavement
> have done so from a theoretical point of view.
They have replied from experience. It depends where you ride and on what
sort of sealed surface. Any tyre on wood in the rain is asking for
trouble except at slow speeds. Likewise anything on smooth tar (ie tar
bands, wet manhole covers, and paint stripes). On normal new tarmac I
find slicks to be just as good as treaded tyres if not better.
Maybe your roads are different.
On snow I find a good tread and studs give me far more traction than
slicks.
> Armchair theories are one
> thing, but this thread is becoming similar to the 'brains on road' thread in
> that actual real-life experiences are being discounted to the point that they
> must not have existed, since they discredit the theories being spewed forth.
>
> I've ridden slicks under the same conditions as treaded with more slipping in
> the wet; others have reported similar happenings.
Your experiences don't make a general rule. It depends on the surface
you are riding on.
Further, I've found that
> slicks cut easier, which I would assume is due to softer rubber. How would
> you explain it, Jobst? Your assumption that all bicycle tires use the same
> hardness of rubber is an awfully big one!
A slick tyre tends to have a thinner layer of rubber and has more rubber
in contact with the road therefore is more likely to pick up punctures
(though my experience is exactly the opposite but I wouldn't say it is a
ny where near statistically significant as I have neither carried out a
strictly controlled test nor (fortunately) had enough punctures to make
it worth the hassle of picking one of them on the basis of puncture
resistance.
>
> >If this example does not demonstrate how strong boundary layers are,
> >you might consider the razor blade that does not penetrate the
> >boundary layer of water on your skin when you shave.
in most cases, but it does cut the hairs. Something to do with local
pressure points?
>
> Well, then, I guess we'd better stop driving our cars around in the rain. As
> Jobst has pointed out, it's virtually impossible to cut through the 'boundary
> layer' to obtain traction - even a razor blade can't!
depends on speed, pressure gradients, amount of water needing moving,
and so on.
On certain outlying circumstances the boundary layer will not be removed
and you will slide. Typical examples are paint stripes and railroad
tracks.
Most of the time this doesn't happen. One would imagine (and I have
experienced this) great instability when a bicycle loses the friction
between road and tyre.
..d
--
* David Martin - Atherosclerosis and Thrombosis research group *
* http://www.uio.no/~damartin/ david....@biotek.uio.no *
* Lab +47 22 95 84 54 Fax +47 22 69 41 30 GSM +47 90 74 27 65 *
Dave Van den Branden
A smooth tire with some small grooves in it to remove some of the water
has worked best for me. I find that knobby or aggressively treaded
tires don't hold corners as well in any weather condition on roads. Off
road is a different story. The tread is necessary for forward
propulsion and to bite through the mud and sand in corners.
The problem with knobby tires on road, wet or dry, is that every gap or
space between tread lugs is an opportunity for the tire to let go and to
slip.
Speaking from experience,
Dave
Jobst Brandt
Rich Haubert writes:
>>> Someone else has objected to the word "hydroplaning"; let's just
>>> use slipping or sliding instead. I only once noticed a problem
>>> with a slick tire. I was on a smooth highway on a wet day, and I
>>> almost lost control from a fresh paint stripe. Traction was zero
>>> for an instant.
>> As I have often pointed out. There is no tire that will give
>> traction on a slick surface such as a paint stripe, manhole cover,
>> railroad track or any smooth homogeneous material with a water film
>> on it. It takes micro grit to penetrate the lubricating water layer.
> Unfortunately, those who have responded in support of slicks on wet
> pavement have done so from a theoretical point of view. Armchair
> theories are one thing, but this thread is becoming similar to the
> 'brains on road' thread in that actual real-life experiences are
> being discounted to the point that they must not have existed, since
> they discredit the theories being spewed
Don't worry, it's not theoretical. I worked with Avocet and defined
the tread thicknesses and compound used in Avocet tires. They are the
same as those used by Ritchey and IRC. In fact IRC makes all three of
these. IT is hard enough to come up with a durable tread compound
that works wet and dry. Altering the durometer is not something you
dial in for various tires. If the rubber tracks well on a patterned
tread, it works well on a slick. The physics does not change.
> I've ridden slicks under the same conditions as treaded with more
> slipping in the wet; others have reported similar happenings.
> Further, I've found that slicks cut easier, which I would assume is
> due to softer rubber. How would you explain it, Jobst? Your
> assumption that all bicycle tires use the same hardness of rubber is
> an awfully big one!
Your contention that they are different is greater conjecture and putting
it forth as fact is whatever word you like best. I call it lying.
> It's certainly possible I just didn't happen to use good slicks. I
> used two different brands, but not the beloved Avocets Jobst
> recommends. Of course, for what they cost, Avocets certainly SHOULD
> be superior. What model do you recommend, Jobst?
Oh bull shit. Now you're going to back down from your authoritative BS
and throw yourself at the mercy of the net.
> Although I usually use Conti's, I don't put much stock in
> manufacturer-sponsored 'tests'. Thus, that data isn't terribly useful.
You have to read between the lines, see how much data is presented
and how much "interpretation" or spin is applied to the evaluation. I
am amazed what poor BS detectors some readers of the net have. There
is a saying that hucksters are the best targets for a scam. Maybe
that's the problem.
>> If this example does not demonstrate how strong boundary layers are,
>> you might consider the razor blade that does not penetrate the
>> boundary layer of water on your skin when you shave. If you dry your
>> skin with alcohol, allowing it to evaporate, a sharp blade will cut
>> the skin. The argument that a slick tire caused a slip on a railroad
>> track is like saying the slick caused you to fall on ice.
> Well, then, I guess we'd better stop driving our cars around in the
> rain. As Jobst has pointed out, it's virtually impossible to cut
> through the 'boundary layer' to obtain traction - even a razor blade
> can't!
Oops, you cut out the part about why tires work on wet pavement, so
maybe you need a course in editing and truthful citations.
You're squirming Rich.
Jobst Brandt <jbr...@hpl.hp.com>
Garry Lee
THis is nonsense.
I cycle in Ireland and have used slicks here for 10 years. They do not have
inferior grip in the wet. In the winter here the roads would be wet for 90%
of rides.
In fact I demonstrated their superior roadholding in the wet to some
friends of mine one day when climbing a steep wet hill. I was the only
person whose tyres were not slipping.
Dr. David Martin
Jobst Brandt wrote:
> The argument that a slick tire caused a slip on a railroad
> track is like saying the slick caused you to fall on ice.
Indeed. I use semi slicks most of the time and they do slip on ice.
Thats why I use studded tyres on ice and they don't slip anywhere near
as much. They're far worse on metal manhole covers though (most
interesting...).
Jobst Brandt
Dr.(biophysics) David Martin writes:
> Do tyres grip as well in wet conditions?
Wait a minute. You just told us that they hydroplane. Now you ask
whether they grip in the wet. The Dr. is [OUT].
> The incident I was referring to was on very smooth asphalt, almost
> as smooth as a paint strip. In most cases the asphalt provides
> enough pressure points (each stone) to allow a high pressure point
> from which the water will be dispelled. Now, you know as well as I
> do that for something to move there has to be a pressure gradient,
> and the larger the gradient the greater the force.
I don't recall "an incident" but rather that you flatly stated that
smooth tires hydroplane. That traction is poorer on wet surfaces is
well known. That new pavement has residual oil and that this reduces
traction, especially with water, is also known. That tread patterns
improve this situation was your contention and I explained why that is
not the case, as long as hydroplaning is not occurring, because
boundary layer fluid is difficult to displace.
It is not each stone, but the fine structure of those bits of gravel
that cause traction. Traction is affected by the dimensions in
micrometers, about at the limit of unmagnified visible observation.
>> How about not alluding to knowledge that you don't have.
> I don't believe I did. My research affiliation is shown clearly in my
> sig. I have never claimed to be an expert researcher in tyre mechanics,
> I was merely putting forward a lay explaination.
So why do you list it? Your sig is at the bottom. I hope you
introduce yourself at social gatherings as Dr. That way in the event
of a medical emergency, you will be the first called. I guess you
worked hard for that title.
>>> On loose surfaces the grip depends on the shear between the dirt
>>> and the underneath. That is why MTBs have big tractor like tread,
>>> to dig down into the dirt and push it with a big shear plane.
>>> Otherwise you end up using the top surface layer as a row of tiny
>>> ball bearings and just spin.
>> If the tire does not make an impression on the soil, the tread does
>> not improve traction as you claim.
> Indeed. that is why tread has no effect on immovable substrates, and
> why slicks are faster on solid surfaces.
Oops, how did "substrates" slip in here. I see you are truly a
scientist who rides around on substrates. Wow.
>> The knobs can reach hardpack between the 'marbles', but this is
>> only under ideal conditions. The main effect is that a larger low
>> pressure tire gets a broader average of the loose surface.
> But that would mean that slicks and treaded tyres of the same
> dimensions have the same grip. Which is not true.
That is an unwarranted deduction. The point is that knobs don't give
the traction advantage that is often attributed to them mainly because
they are wasted on a hard surfaces.
>>> Try taking an MTB fitted with a treaded tyre and a then with
>>> slicks through a hard corner on tarmac. You'll soon notice the
>>> difference.
>> Yes, the knobby washes out at about half the lateral thrust. But
>> then we weren't talking about knobby tires, but rather smooth or
>> treaded road tires that have pseudo automotive tread.
> Depends what you consider an 'automotive tread'. Here we have a lot
> of M+S rated tyres. they look more like MTB tyres.
The point is that you changed the subject. We were talking about
tread having a positive effect on wet pavement, not whether knobs work
in the dirt.
> These treads may conceivably make a difference in some extremely rare
> circumstances, but are probably there for marketing purposes (or as a
> handy depth guage to let you know when the tyre is worn out).
Thanks. I think we're back where we started. In fact I am sure I
said that in this thread. How perceptive of you to notice.
>>> Its also strange how race cars use slicks in almost every race
>>> except when they need to worry about aquaplaning.
>> To you it may be strange, but to those who understand that even
>> rain tires in F1 have slick tread areas larger than those of a
>> bicycle, yet they travel at substantially greater speed and with
>> lower tire pressure.
> I'll have to try to write in American instead of English. In the wet
> in F1 hydroplaning is a given. That is what the above statement
> alluded to though in a typically British manner. The principal is
> established that hydroplaning can occur.
That has not been established and if the UK uses a different
definition of aquaplaning/hydroplaning then you'll have to supply
that. Here and on the continent it is separation of tire and road by
liquid water in contrast to boundary layer wetness of the contacting
surfaces. Those who have experienced it know that the steering of a
car turns freely and without effect when hydroplaning.
> A quick definition that you may care to dispute: 'Hydroplaning
> occurs when the speed of removal of water from between the tyre and
> the road is insufficient to allow the tyre to contact the road.'
You'll have to do better than that because contact is also lacking in
precise meaning here. As I said, the result is flotation and that
fits your definition as well.
> In the wet in bike racing hydroplaning is rare (not non existent).
You can ride through water deeper than the depth of tire and rim and
not get hydroplaning at speeds up to 40 mph on a bicycle. I have
ridden through such water without falling and had good steering
control. A two wheeled vehicle cannot be ridden any distance while
hydroplaning because it offers less traction than smooth ice at the
melting point.
> If you put two smooth surfaces together (ie a paint stripe and a
> slick tyre) with a layer of water between them, you will get
> hydroplaning under certain conditions (relatively high speed).
That is not hydroplaning. That is boundary layer lubrication. As
I pointed out, smooth homogeneous surfaces have no fine structure
that can break through the boundary layer as does the fine grit of
conglomerate paving rock or the sharp facets of crystalline rock
surfaces.
> Having a tread makes the interface less smooth, giving points of
> higher pressure, giving a pressure gradient, giving exclusion of
> water from the interface so increases the amount of rubber on the
> road at that point.
I guess you missed the item about a squeegee and that its edge is
the sharpest rubber edge offered commercially. It glides over water
on glass effortlessly. If you think you know of a tire tread that can
do better than that, please don't keep it a secret.
> Of course this only really matters if you are running slicks on a
> slick surface. I happened to find one such surface (on which braking
> in the dry is very good on the same tyres) in the rain and the water
> removal at the speed I was going (which was too fast for the
> conditions) was insufficient. I have never experienced it on tarmac
> since, just on paint stripes and manhole covers or similar features.
Yes? And have you compared your slicks with other tires on these same
surfaces? I doubt you will find any difference. In fact a good way
to fall on you ass on a wet surface is to put the rear edge of a
rubber heel on it. The flat surface of a rubber sole usually has
enough grit on it to prevent sliding. Vibram soles contain plenty of
carbon black for that purpose.
Jobst Brandt <jbr...@hpl.hp.com>
Joshua_Putnam
In <haubert.38...@mbi.org> hau...@mbi.org writes:
>Unfortunately, those who have responded in support of slicks on wet pavement
>have done so from a theoretical point of view.
I wouldn't call a lifetime of riding year-round in the Pacific
Northwet "theoretical." On relatively clean pavement, wet or
dry, slicks win no questions asked. Even under a foot of
standing water when the roads flood, if the pavement is clean,
slicks work better. Only when there is significant silt or sand
on the pavement is tread worthwhile, and then the decorative
little siping found on most road tires isn't worth much, if
anything, while a deep inverted tread gives a better grip without
being as noisy as a knobby off-road tire.
>I've ridden slicks under the same conditions as treaded with more slipping in
>the wet; others have reported similar happenings. Further, I've found that
>slicks cut easier, which I would assume is due to softer rubber. How would
>you explain it, Jobst? Your assumption that all bicycle tires use the same
>hardness of rubber is an awfully big one!
I can't say all bicycle tires use the same hardness of rubber,
but then neither did Jobst. I can confirm that IRC Japan
doesn't use softer rubber on its slicks than on its treaded road
tires, since I've used both and cut both up for tire boots.
Unless I'm mistaken IRC Japan makes Avocet's tires, too, as well
as many of Ritchey's tires, including the Cross-Bite and the
better grade of Tom Slicks.
I would assume the real difference is simply the thinner, lighter
tread rubber on slicks, which can be cut through more easily than
the thicker rubber needed to build a decorative pattern.
In any case, I certainly haven't noticed more flats with slicks
than with lightweight treaded tires in my own riding.
--
Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
"My other bike is a car."
http://www.wolfenet.com/~josh
Dr. David Martin
Jobst Brandt wrote:
>
> Dr.(biophysics) David Martin writes:
>
> > Do tyres grip as well in wet conditions?
>
> Wait a minute. You just told us that they hydroplane. Now you ask
> whether they grip in the wet. The Dr. is [OUT].
My apologies. It has emerged quite clearly that I was mistaking
hydroplaning for boundary layer lubrication. The two are very similar
but distinct as has clearly been pointed out by Jobst.
It appears that the incident (to which I did refer earlier) is
obviously boundary layer lubrication causing a loss of friction between
tyre and road.
> >> How about not alluding to knowledge that you don't have.
>
> > I don't believe I did. My research affiliation is shown clearly in my
> > sig. I have never claimed to be an expert researcher in tyre mechanics,
> > I was merely putting forward a lay explaination.
>
> So why do you list it? Your sig is at the bottom. I hope you
> introduce yourself at social gatherings as Dr. That way in the event
> of a medical emergency, you will be the first called.
No, not at all. I am a scientist not a clinician. I am employed as a
scientist. For the majority of my email and News work this is relevant.
For some it isn't. I never introduce myself as 'Dr.' at social
gatherings, people start to either assume I am some mad professor on a
mission to destroy the place, or start to ask me for medical advice.
Both of these I can quite happily do without. And it isn't that often at
a party that you find a molecular biologist or a protein engineer...
I found the best answer at parties to 'what do you do?' (apart from 'I
spend taxpayers money on torturing small animals') is just to say 'I
work at the university' at which point they assume that I am obviously
normal rather than an academic and will talk about something interesting
instead of work.
> > Indeed. that is why tread has no effect on immovable substrates, and
> > why slicks are faster on solid surfaces.
>
> Oops, how did "substrates" slip in here. I see you are truly a
> scientist who rides around on substrates. Wow.
We all ride on substrates (or in the case of mud, in substrates <g>)
Just a term that crept in. I must try to learn american to write my
posts.
> >> Yes, the knobby washes out at about half the lateral thrust. But
> >> then we weren't talking about knobby tires, but rather smooth or
> >> treaded road tires that have pseudo automotive tread.
>
> > Depends what you consider an 'automotive tread'. Here we have a lot
> > of M+S rated tyres. they look more like MTB tyres.
>
> The point is that you changed the subject. We were talking about
> tread having a positive effect on wet pavement, not whether knobs work
> in the dirt.
not changed. Drifted. A common feature of usenet threads..
>
> > These treads may conceivably make a difference in some extremely rare
> > circumstances, but are probably there for marketing purposes (or as a
> > handy depth guage to let you know when the tyre is worn out).
>
> Thanks. I think we're back where we started. In fact I am sure I
> said that in this thread. How perceptive of you to notice.
Yes. Now we are talking roughly the same language (and my misconceptions
have been corrected.)
apoogies fro the errors, and thanks for an interesting discussion.
hau...@mbi.org
In article <5lfh8k$4...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst Brandt) writes:
>From: jbr...@hpl.hp.com (Jobst Brandt)
>Subject: Re: slicks vs treads
>Rich Haubert writes:
>> Unfortunately, those who have responded in support of slicks on wet
>> pavement have done so from a theoretical point of view. Armchair
>> theories are one thing, but this thread is becoming similar to the
>> 'brains on road' thread in that actual real-life experiences are
>> being discounted to the point that they must not have existed, since
>> they discredit the theories being spewed
Jobst replies:
>Don't worry, it's not theoretical. I worked with Avocet and defined
>the tread thicknesses and compound used in Avocet tires.
Ah, yes - I had a feeling you had a personal stake in this, Jobst. Your
credibility on this issue is now zero.
>> I've ridden slicks under the same conditions as treaded with more
>> slipping in the wet; others have reported similar happenings.
>> Further, I've found that slicks cut easier, which I would assume is
>> due to softer rubber. How would you explain it, Jobst? Your
>> assumption that all bicycle tires use the same hardness of rubber is
>> an awfully big one!
>Your contention that they are different is greater conjecture and putting
>it forth as fact is whatever word you like best. I call it lying.
Then you don't know the definition of lying. Even if I was wrong, it
wouldn't have been lying. But in fact, I wasn't even wrong, as you admitted
above. In fact, NOT all bike tires use the same hardness.
>> It's certainly possible I just didn't happen to use good slicks. I
>> used two different brands, but not the beloved Avocets Jobst
>> recommends. Of course, for what they cost, Avocets certainly SHOULD
>> be superior. What model do you recommend, Jobst?
>Oh bull shit. Now you're going to back down from your authoritative BS
>and throw yourself at the mercy of the net.
At the mercy of the net? You have an odd demeanor, Jobst. I see - since I am
actually willing to ask for advice, I must be inferior to pig-heads like you
who could never possibly be even a tiny bit wrong. I simply asked for your
advice - but I see now that such advice would be extremely biased, and thus of
no value.
>> Well, then, I guess we'd better stop driving our cars around in the
>> rain. As Jobst has pointed out, it's virtually impossible to cut
>> through the 'boundary layer' to obtain traction - even a razor blade
>> can't!
>Oops, you cut out the part about why tires work on wet pavement, so
>maybe you need a course in editing and truthful citations.
Actually, I've already had that course - from you. Of course I'm not quite as
good at it as my teacher yet.
>You're squirming Rich.
Whatever you say, Jobst. After all, you are the master.
Rich
Bill Weston
Joshua_Putnam wrote:
On relatively clean pavement, wet or
> dry, slicks win no questions asked. Even under a foot of
> standing water when the roads flood, if the pavement is clean,
> slicks work better.
All my experience strongly contradicts this. I find slicks are much much
much more prone to slipping on wet roads. Some tires are much worse than
others. I currently have an IRC Paperlite Plus on my rear rim, which is
basically slick, and I can't even stand up going up hill without
spinning the back wheel if the roads are at all wet. To suggest slicks
work better on wet roads is totally absurd.
Martin A. Gulaian
In a previous article, jbr...@hpl.hp.com (Jobst Brandt) says:
>Rich Haubert writes:
>
>> Although I usually use Conti's, I don't put much stock in
>> manufacturer-sponsored 'tests'. Thus, that data isn't terribly useful.
>
>You have to read between the lines, see how much data is presented
>and how much "interpretation" or spin is applied to the evaluation. I
>am amazed what poor BS detectors some readers of the net have. There
>is a saying that hucksters are the best targets for a scam. Maybe
>that's the problem.
This is maybe slightly off the subject (it involves tread pattern, and
manufacturer's test data, but no flaming), but Avocet is running tire ads
that sure set my BS detector clanging:
They have a new line of offroad tires with a slick ridge on the sides for
better cornering - the ad claims it doesn't break loose until 44 degrees
cornering angle, vs. something like 33 for competing brands. Since 44
degrees is just about the breakout angle for slick tires on smooth
pavement, you can bet that the test was done on a smooth hard surface, and
that a pure road slick would have done even better, and that the results
are totally meaningless for any offroad situation.
I assume they produced these misleading results with Jobst Brandt's
machine...
--
Marty Gulaian - ma...@po.cwru.edu
Thomas H. Kunich
In article <337C5E...@raleigh.hcl.com>,
Bill Weston <bill....@raleigh.hcl.com> wrote:
>I currently have an IRC Paperlite Plus on my rear rim, which is
>basically slick, and I can't even stand up going up hill without
>spinning the back wheel if the roads are at all wet. To suggest slicks
>work better on wet roads is totally absurd.
So, which tires yield BETTER traction?
Thomas H. Kunich
>Ah, yes - I had a feeling you had a personal stake in this, Jobst. Your
>credibility on this issue is now zero.
I knew it would come out. Not only do you not understand simple
physics, but you don't respect knowledge either.
hau...@mbi.org
In article <01bc6212$a5217d20$8e18...@gbwebel.house.gov> "Baird Webel" <we...@potomac.net> writes:
>From: "Baird Webel" <we...@potomac.net>
>Subject: Re: slicks vs treads
>hau...@mbi.org wrote in article <haubert.39...@mbi.org>...
>> In article <5lfh8k$4...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst
>Brandt) writes:
>> Jobst replies:
>>
>> >Don't worry, it's not theoretical. I worked with Avocet and defined
>> >the tread thicknesses and compound used in Avocet tires.
>>
>> Ah, yes - I had a feeling you had a personal stake in this, Jobst.
>Your
>> credibility on this issue is now zero.
>Jobst may have a personal stake in this, but it also means that he has
>been intimately involved with testing and design of tires. He is not
>the only expert who has weighed in with this opinions. Why would
>conti's expert have admitted that slicks were optimal, when his company
>doesn't even produce slicks?
Uh, yes, continental DOES produce slicks. Next question.
Rich
hau...@mbi.org
In article <tomkEAA...@netcom.com> to...@netcom.com (Thomas H. Kunich) writes:
>From: to...@netcom.com (Thomas H. Kunich)
>Subject: Re: slicks vs treads
>In article <haubert.39...@mbi.org>, <hau...@mbi.org> wrote:
>>Ah, yes - I had a feeling you had a personal stake in this, Jobst. Your
>>credibility on this issue is now zero.
>I knew it would come out. Not only do you not understand simple
>physics, but you don't respect knowledge either.
Once again, Thom's juvenile mean streak is showing.
The fact is, I've posted in this group that I DO respect Jobst's knowledge
base, and I still do. In fact, I have his book sitting on the bookshelf in my
family room.
Nevertheless, it is no more meaningful nor legitimate for him to recommend
tires he gets a royalty from than to recommend that people buy 'The Bicycle
Wheel'.
Now do you get it, Thomas? Probably not.....
Rich
hau...@mbi.org
In article <tomkEAA...@netcom.com> to...@netcom.com (Thomas H. Kunich) writes:
>From: to...@netcom.com (Thomas H. Kunich)
>Subject: Re: slicks vs treads
Alas, Bill, your own legitimate experiences will be discounted, denied and
disputed until Thom and company convince themselves that they never existed.
Continental tests show that slicks are better, wet or dry, didn't ya hear? So
the fact that you, I, and probably thousands of other people had bad
experiences with them is meaningless. Oh, well - to each his own.
Rich
David Casseres
> The fact is, I've posted in this group that I DO respect Jobst's knowledge
> base, and I still do. In fact, I have his book sitting on the bookshelf
in my
> family room.
>
> Nevertheless, it is no more meaningful nor legitimate for him to recommend
> tires he gets a royalty from than to recommend that people buy 'The Bicycle
> Wheel'.
Don't be silly. Jobst isn't recommending any particular brand of tire in
this thread, he's telling you that slick tires (which are made by many
different manufacturers) have better traction on wet pavement than treaded
tires (which are made by all the same manufacturers).
As it happens, he is right and you are wrong. You're right about Kunich,
though.
--
Cheers,
David
Thomas H. Kunich
In article <haubert.40...@mbi.org>, <hau...@mbi.org> wrote:
>
>Nevertheless, it is no more meaningful nor legitimate for him to recommend
>tires he gets a royalty from than to recommend that people buy 'The Bicycle
>Wheel'.
So... how do you get from Jobst's admission that he helped develop the
Avocet tires to his getting paid a royalty for them? Am I missing something
here?
In my experience, consulting engineers receive a fee, not a royalty.
>Now do you get it, Thomas? Probably not.....
I'm still back at your insistance that a tire pumped up to 35 psi can
push down on the road harder than 35 psi.
Of course this is all my juvenile meaness that suggests to me that
your ideas of the world around you are...incomplete.
Thomas H. Kunich
>Alas, Bill, your own legitimate experiences will be discounted, denied and
>disputed until Thom and company convince themselves that they never existed.
>
>Continental tests show that slicks are better, wet or dry, didn't ya hear? So
>the fact that you, I, and probably thousands of other people had bad
>experiences with them is meaningless. Oh, well - to each his own.
You understate as usual: Continental's engineers as well as Michelin's
and Avocet's. I'm sure that IRC and Specialized would also agree but
the real test, as you see, is whether or not a tire ever slipped under
you and whether or not it had tread on it, not a real test of whether
or not two tires would have slipped at different loadings under
the same conditions.
Of course your crude approximations are much more accurate than a
machine which can actually measure these values to fractions of a
percent. Your senses are much more accurate than these silly machines
and your memory of conditions is much more accurate than controlled
testing.
Eric P. Salathe, Jr.
Jobst Brandt wrote:
> I worked with Avocet and defined
> same as those used by Ritchey and IRC.
So can you tell me if the Fasgrip Duro (700x32C) is truly discontined? I
have used IRC tires extensively on both singles and tandems, and wanted
to replace IRC Tandems (700x30c) with the Duro to get a properly slick
tread, but apparently this size is unavailable on either coast. I have
settled for the Tom Slick (ambiguously marked 700x30C and 32-622), which
seems similar despite their decorative 'vector analysis tread design',
but much less pricey.
--
,
Eric P. Salathe, Jr. sal...@atmos.washington.edu
Seattle WA
Eric P. Salathe, Jr.
> Unfortunately, those who have responded in support of slicks on wet pavement
> have done so from a theoretical point of view. Armchair theories are one
I'm sorry, but this arguement truly irks me. The phrase `armchair
theory' is just plain ignorant. Data are collected in the field or lab,
but it is understood in the arm chair.
This is an abstract medium; do you expect a demonstration transported
over the internet? A logical arguement we can follow and discuss; a
vague catalogue of experiences is basically worthless. Otherwise, go
ride.
redmist
I follow Formula One racing as well as cycling. The guys with the big bucks
go to treads...deep treads in the seriously wet. If conditions are damp
they use slicks....hoping it will dry out. I'been using a set of the new
Grand Prix 3000 Contis. They have a tread pattern but are very slippery
because of the compound used. The grip you will experience is a combination
of both the tire compound and the tread pattern.
Jobst Brandt <jbr...@hpl.hp.com> wrote in article
<5lfk0m$4...@hplms2.hpl.hp.com>...
Kirk R. Darling
Jobst, do bicycle tires actually hydroplane at all? Some one has told me
that due to the physics involved, the tiny area of contact of a bicycle
tire never does hydroplane in the same way as the much larger contact area
of an automobile tire. In fact, according to this person, the contact area
of a bicycle is about the size of the contact area of a section of tread of
a good wet-condition auto tire. This seemed logical to me, although I
don't know the physics of it.
--
KRD
"Leap boldly. You can't cross a chasm in two easy steps."
Jobst Brandt <jbr...@hpl.hp.com> wrote in article >
<snip>
I don't recall "an incident" but rather that you flatly stated that
> smooth tires hydroplane. That traction is poorer on wet surfaces is
> well known. That new pavement has residual oil and that this reduces
> traction, especially with water, is also known. That tread patterns
> improve this situation was your contention and I explained why that is
> not the case, as long as hydroplaning is not occurring, because
> boundary layer fluid is difficult to displace.
><snip>
Baird Webel
hau...@mbi.org wrote in article <haubert.39...@mbi.org>...
> In article <5lfh8k$4...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst
Brandt) writes:
> Jobst replies:
>
> >Don't worry, it's not theoretical. I worked with Avocet and defined
> >the tread thicknesses and compound used in Avocet tires.
>
> Ah, yes - I had a feeling you had a personal stake in this, Jobst.
Your
> credibility on this issue is now zero.
Jobst may have a personal stake in this, but it also means that he has
been intimately involved with testing and design of tires. He is not
the only expert who has weighed in with this opinions. Why would
conti's expert have admitted that slicks were optimal, when his company
doesn't even produce slicks?
baird
Omar Sze Leung
On Fri, 16 May 1997, Thomas H. Kunich wrote:
> In article <haubert.40...@mbi.org>, <hau...@mbi.org> wrote:
> >Alas, Bill, your own legitimate experiences will be discounted, denied and
> >disputed until Thom and company convince themselves that they never existed.
> >experiences with them is meaningless. Oh, well - to each his own.
>
> Of course your crude approximations are much more accurate than a
> machine which can actually measure these values to fractions of a
> percent. Your senses are much more accurate than these silly machines
> and your memory of conditions is much more accurate than controlled
> testing.
In "Tyre Technology", Tom French, the former Development Manager at
Dunlop, related a true story that might relate.
A magazine offered an award to anyone who could improve the adhesion of
the ends of walking canes during slippery and wet conditions.
Many well known scientists submitted entries, but the winner was an old
woman who crocheted some string into an end cap for the stick. Her
comment was that "everyone knows that it works"
Seriously, though, hasn't Bridgestone introduced a rain/snow car tire, the
"Blizzak", that uses small pores as a microtread? This type of
microporous material seems like it would have promise in two wheel
vehicles.
Omar Leung
Jobst Brandt
Rich Haubert writes:
> The fact is, I've posted in this group that I DO respect Jobst's
> knowledge base, and I still do. In fact, I have his book sitting on
> the bookshelf in my family room.
Thanks for the purchase, I hope you found it useful.
> Nevertheless, it is no more meaningful nor legitimate for him to
> recommend tires he gets a royalty from than to recommend that people
> buy 'The Bicycle Wheel'.
You don't know that. I am neither on the staff of Avocet, get paid
for any of my consulting work, or hold any paid position there. What
I have contributed is a hobby, and that includes the Cyclometers, the
shoes, the tires, and altimeters. I hold patents for several of these
things and Bud Hoffacker, my good friend runs the company that is an
offshoot of his father's bike shop, where my parents got their bikes
and where I recall my earliest bicycle shop experiences. It was on
that basis that Bud and I worked together on these projects. I buy my
tires in his store.
As I said, you'll have to read between the lines to see whether what
someone on the net is credible, consistent and not biased. That is an
important part of life. Suckers are everywhere, but you don;t have to
be one.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Bill Weston writes:
> I currently have an IRC Paperlite Plus on my rear rim, which is
> basically slick, and I can't even stand up going up hill without
> spinning the back wheel if the roads are at all wet. To suggest
> slicks work better on wet roads is totally absurd.
I think you'll find that this has been tested by more people than
Continental. IRC and Avocet have done the same and found that slicks
of similar size and rubber compound track better than patterned tread.
Your perception may be different, but were you able to do a controlled
experiment, I am sure you would find likewise.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
David Martin writes:
> My apologies. It has emerged quite clearly that I was mistaking
> hydroplaning for boundary layer lubrication. The two are very
> similar but distinct as has clearly been pointed out by Jobst.
I think this may be a general misconception, judging from some of the
posts to this subject. It takes a few questions on the subject to
clarify what is understood and not, albeit in question form, rather
than as rhetorical statement that may be misinterpreted.
> It appears that the incident (to which I did refer earlier) is
> obviously boundary layer lubrication causing a loss of friction
> between tyre and road.
It's a little more than just that. It is flotation on a substantial
water layer. As I said, one can turn the steering wheel of a car
effortlessly and with no effect when this happens. It is similar to
driving on wet ice.
> I never introduce myself as 'Dr.' at social gatherings, people start
> to either assume I am some mad professor on a mission to destroy the
> place, or start to ask me for medical advice.
Different countries, different customs. I believe the title is out of
place on wreck.bike. I doubt that a doctorate has been offered in
bicycling. Only Ed Burke lists himself as Dr. (MD) and should be
ashamed of it, considering the drugs and blood doping experiments that
occurred among our bicyclists in the Los Angeles Olympics.
> Yes. Now we are talking roughly the same language (and my
> misconceptions have been corrected.)
> apologies for the errors, and thanks for an interesting discussion.
That's about the most civil reply I have seen in response to a rebuke
I generally reserve for people who seriously propose technical matters
that are based on urban legends. It's been interesting.
Excuse me for underestimating you Dave.
Jobst Brandt <jbr...@hpl.hp.com>
Joshua_Putnam
>Joshua_Putnam wrote:
> On relatively clean pavement, wet or
>> dry, slicks win no questions asked. Even under a foot of
>> standing water when the roads flood, if the pavement is clean,
>> slicks work better.
>All my experience strongly contradicts this. I find slicks are much much
>much more prone to slipping on wet roads. Some tires are much worse than
>others. I currently have an IRC Paperlite Plus on my rear rim, which is
>basically slick, and I can't even stand up going up hill without
>spinning the back wheel if the roads are at all wet. To suggest slicks
>work better on wet roads is totally absurd.
You may find it absurd, but descending at 30+ mph in the rain,
I'd much rather be riding good slicks than any treaded tire I've
tried. I've climbed and descended many mountain passes and
smaller hills with both slicks and treaded tires, and I can't
agree with your assessment of slicks.
d. schultz
Omar Sze Leung wrote:
>
> A magazine offered an award to anyone who could improve the adhesion of
> the ends of walking canes during slippery and wet conditions.
>
> Many well known scientists submitted entries, but the winner was an old
> woman who crocheted some string into an end cap for the stick. Her
> comment was that "everyone knows that it works"
>
> Seriously, though, hasn't Bridgestone introduced a rain/snow car tire, the
> "Blizzak", that uses small pores as a microtread? This type of
> microporous material seems like it would have promise in two wheel
> vehicles.
>
> Omar Leung
Don't know if it is related, but fly fishermen and women have preferred
waders and boots with felt soles on the bottom over rubber hip boots with
massive tread for quite a while. Barring felt, cork soles or bare feet
are best when walkin on on smooth slippery rocks in fast moving trout
waters.
I have slicks front and back on my Vision recumbent, and maintain that
loose farm dogs are the biggest crash threat. . .
Lloyd in Wisconsin
Rick Denney
...snip...
>
> I'm still back at your insistance that a tire pumped up to 35 psi can
> push down on the road harder than 35 psi.
>
I've missed this thread, but I can't resist responding to this. 35 psi
is the pressure inside the tire. When weight is applied to the tire, two
things will happen. The first is that the tire will spread out, making a
larger contact patch. The second is that the tire pressure will
increase. Both occur, but the spread of the contact patch is by far the
greater effect, I suspect. If I weigh 200 pounds including the bike, and
my tires have 100 psi in them, then the contact patch is 2 square inches
for both tires combined. If I gain a lot of weight, and now weigh 300
pounds with bike, then the contact patch will be 3 square inches,
achieved by the tire squashing down a bit more. But that only applies
when the tire pressures are measured under full load.
When I raced cars, we would stump newbies by asking them which had a
bigger contact patch, given the same car and tire pressure, a
5-inch-wide street tire, or an 8-inch-wide racing slick. Answer: they
are both the same. The street tire's contact patch is longer than it is
wide, and the slick's is wider than it is long, but they both cover the
same real estate.
Rick Denney
redmist wrote:
>
> I follow Formula One racing as well as cycling. The guys with the big bucks
> go to treads...deep treads in the seriously wet. If conditions are damp
> they use slicks....hoping it will dry out. I'been using a set of the new
> Grand Prix 3000 Contis. They have a tread pattern but are very slippery
> because of the compound used. The grip you will experience is a combination
> of both the tire compound and the tread pattern.
>
contact patch is therefore very big. An F1 race car will place something
like 500 pounds on each tire (to pull a plausible number out of the
air). The tire probably has about 40 psi in it. That means that the
contact patch is 12 square inches. If the tire is 12 inches wide, then
the contact patch is 12 inches wide and 1 inch long. Water will pile up
under a patch of that shape. And it will pile up in a hurry: the car is
going 150 miles an hour.
A bicycle contact patch is probably about a square inch, and is
something a half inch wide and two inches long. Not much water will pile
up there, especially given that the speeds are very much lower than the
race car.
Each tread block of a treaded rain tire for a race car is probably twice
as big as the enture contact patch on a bicycle. Kinda makes you think,
doesn't it?
And another thing. Race cars use slip angles to resist lateral forces.
The force of cornering is resisted by the tire at an angle to the
centerline of the wheel. That makes the tire deform into an S curve as
it touches the pavement. Water in there does really terrible things.
Bicycle (and motorcycle) tires do not have to resist lateral forces: the
lean of the bicycle means that all forces are always applied straight
down through the wheel (otherwise, you fall). No slip angles. Water can
be squeegied aside, rather than getting trapped by the deformation of a
tire undergoing scrub.
Ain't physics great?
Jobst Brandt
Rick Denney writes:
> I've missed this thread, but I can't resist responding to this. 35 psi
> is the pressure inside the tire. When weight is applied to the tire, two
> things will happen. The first is that the tire will spread out, making a
> larger contact patch. The second is that the tire pressure will
> increase.
Well you're wrong about the inflation pressure unless you are
splitting hairs. On a conventional tire gauge, you will not see any
difference in pressure when you let the car off the jack, so to speak.
An unloaded tire inflated to 35psi remains at 35psi when the weight of
the car is lowered onto it. I guess you missed that part of inflating
spare tires when you were a kid. The same goes for a bicycle tire.
Most people pump their tires without anyone sitting on the bike. The
pressure is the same when they ride, for measurable pressures.
> Both occur, but the spread of the contact patch is by far the
> greater effect, I suspect. If I weigh 200 pounds including the bike, and
> my tires have 100 psi in them, then the contact patch is 2 square inches
> for both tires combined. If I gain a lot of weight, and now weigh 300
> pounds with bike, then the contact patch will be 3 square inches,
> achieved by the tire squashing down a bit more. But that only applies
> when the tire pressures are measured under full load.
Wrong. Try it instead of hypothesizing on it and lecturing on what
you imagine.
> When I raced cars, we would stump newbies by asking them which had a
> bigger contact patch, given the same car and tire pressure, a
> 5-inch-wide street tire, or an 8-inch-wide racing slick.
The effective contact area of the slick is bigger, less laterally
deformable and flat as a pancake, so it will hydroplane easily, there
being no place for the water to go in the squish of the advancing tire
but forward, where there is already water approaching at road speed.
If you have dived from a ten meter swimming pool tower, or motorcycled
in the rain, you should know how hard water gets at speed.
Jobst Brandt <jbr...@hpl.hp.com>
David Cruz
Recently, I bought a pair of Continental Goliaths tires. The Goliath is
a cross between a slick and treaded tire; I'd say it's more of a slick
than a treaded tire. Nevertheless it's a great tire for wet weather,
city driving, and even some light trail riding. I recommend it highly.
Ciao,
D.C.
Jobst Brandt
Eric Salathe writes:
> So can you tell me if the Fasgrip Duro (700x32C) is truly discontinued?
The Duro 700x32C is in stock and should be available. Have your
dealer place an order. Avocet is back on track now after a temporary
change in management. I expect good things coming. We are working on
a new Cyclometer that I think will make a lot of riders happy.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Marty Gulaian writes:
>> You have to read between the lines, see how much data is presented
>> and how much "interpretation" or spin is applied to the evaluation. I
>> am amazed what poor BS detectors some readers of the net have. There
>> is a saying that hucksters are the best targets for a scam. Maybe
>> that's the problem.
> This is maybe slightly off the subject (it involves tread pattern,
> and manufacturers test data, but no flaming), but Avocet is running
> tire ads that sure set my BS detector clanging:
> They have a new line of offroad tires with a slick ridge on the
> sides for better cornering - the ad claim it doesn't break loose
> until 44 degrees cornering angle, vs. something like 33 for
> competing brands. Since 44 degrees is just about the breakout angle
> for slick tires on smooth pavement, you can bet that the test was
> done on a smooth hard surface, and that a pure road slick would have
> done even better, and that the results are totally meaningless for
> any offroad situation.
That was the intention of the design. By having a continuous and solid
tread feature down in the low angle zone, these tires run as well as
slicks on pavement.
> I assume they produced these misleading results with Jobst Brandt's
> machine...
The lean angles were measured using that machine. I contributed to
the design of that tread and was satisfied that it achieved its goal.
Several bicycle magazines were invited to test them on a moderately
solid dirt road on a specific curve between timing lights. The best
ten runs on each tire were recorded. The new Avocet tires came off
the best against the leaders in the dirt tire field, including Ritchey
and Specialized.
Unfortunately MTB action that was the most enthusiastic about the
results did not publish their results, and I can only imagine that
they had advertiser problems. The sports editor did the bike riding
and was going to write a piece on it but in the last moment he
assigned another writer to write a "responsive", "quick", "lively"
article from having the tires in his hands.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Kirk Darling writes:
> Do bicycle tires actually hydroplane at all? [long dissertation
> proving that this question is being asked for lack of understanding
> deleted]
No. As was previously pointed out in this thread, the shape of the
tire above all, as well as its width and contact pressure, prevent
flotation until speeds above those normally attainable by bicycles,
even on descents, impossible.
The round cross section causes a contact patch that is a long narrow
canoe shape to develop from the advancing point that spreads to
displace water laterally. Commercial aircraft do likewise with
similarly round cross section tires, except that they do this up to
speeds of 200mph without hydroplaning.
Jobst Brandt <jbr...@hpl.hp.com>
Kirk R. Darling
You seem to be saying something in line with what I've been told before.
Essentially, bicycle tires don't hydroplane as do automobile tires, thus
there is no need for siping tread on pavement. By the same token
(according to what I've been told), since there isn't a soft surface for a
molded tread to bite into, the best traction is from a slick.
KRD
"Leap boldly. You can't cross a chasm in two easy steps."
Rick Denney <rde...@mail.viggen.com> wrote in article
> >
> Yes, but F1 race cars are very heavy compared to a bike and rider. The
> contact patch is therefore very big. An F1 race car will place something
> like 500 pounds on each tire (to pull a plausible number out of the
> air). The tire probably has about 40 psi in it. That means that the
> contact patch is 12 square inches. If the tire is 12 inches wide, then
> the contact patch is 12 inches wide and 1 inch long. Water will pile up
> under a patch of that shape. And it will pile up in a hurry: the car is
> going 150 miles an hour.
>
> A bicycle contact patch is probably about a square inch, and is
> something a half inch wide and two inches long. Not much water will pile
> up there, especially given that the speeds are very much lower than the
> race car.
>
> Each tread block of a treaded rain tire for a race car is probably twice
> as big as the enture contact patch on a bicycle. Kinda makes you think,
> doesn't it?
>
<snip>
Kirk R. Darling
Russian naval vessels (at least those I've been on) have smooth steel decks
(not the non-skid that US vessels have). Their sailors wear little rubber
booties with slick soles.
Topsider boat shoes have only thin siping, not heavy tread, too.
--
KRD
"Leap boldly. You can't cross a chasm in two easy steps."
d. schultz <schu...@gemed.med.ge.com> wrote in article
<337DED...@gemed.med.ge.com>...
>
> Don't know if it is related, but fly fishermen and women have preferred
> waders and boots with felt soles on the bottom over rubber hip boots with
> massive tread for quite a while. Barring felt, cork soles or bare feet
> are best when walkin on on smooth slippery rocks in fast moving trout
> waters.
>
><snip>
> Lloyd in Wisconsin
>
hau...@mbi.org
In article <5lj4ma$l...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst Brandt) writes:
>From: jbr...@hpl.hp.com (Jobst Brandt)
>Subject: Re: slicks vs treads
>Rich Haubert writes:
>> The fact is, I've posted in this group that I DO respect Jobst's
>> knowledge base, and I still do. In fact, I have his book sitting on
>> the bookshelf in my family room.
Jobst replies:
>Thanks for the purchase, I hope you found it useful.
Yeah, it's good. I found out that some people are even more anal than me!
>> Nevertheless, it is no more meaningful nor legitimate for him to
>> recommend tires he gets a royalty from than to recommend that people
>> buy 'The Bicycle Wheel'.
>You don't know that. I am neither on the staff of Avocet, get paid
>for any of my consulting work, or hold any paid position there. What
>I have contributed is a hobby, and that includes the Cyclometers, the
>shoes, the tires, and altimeters. I hold patents for several of these
>things
Well, then you DO get royalties, right? I sure hope you do - it certainly
sounds like you deserve them.
and Bud Hoffacker, my good friend runs the company that is an
>offshoot of his father's bike shop, where my parents got their bikes
>and where I recall my earliest bicycle shop experiences. It was on
>that basis that Bud and I worked together on these projects. I buy my
>tires in his store.
Jobst, I understand your position. I would place your knowledge level about
bike wheels and tires above anyone else I have ever read or talked to.
>As I said, you'll have to read between the lines to see whether what
>someone on the net is credible, consistent and not biased. That is an
>important part of life. Suckers are everywhere, but you don;t have to
>be one.
Yeah, the net is like that! And you're right - I should have given you the
benefit of the doubt. To you, I apologize. And thanks for giving me an easy
out.
Rich
Mark Atanovich
In article <5lj501$l...@hplms2.hpl.hp.com>
jbr...@hpl.hp.com (Jobst Brandt) writes:
> Bill Weston writes:
>
> > I currently have an IRC Paperlite Plus on my rear rim, which is
> > basically slick, and I can't even stand up going up hill without
> > spinning the back wheel if the roads are at all wet. To suggest
> > slicks work better on wet roads is totally absurd.
>
> I think you'll find that this has been tested by more people than
> Continental. IRC and Avocet have done the same and found that slicks
> of similar size and rubber compound track better than patterned tread.
> Your perception may be different, but were you able to do a controlled
> experiment, I am sure you would find likewise.
>
> Jobst Brandt <jbr...@hpl.hp.com>
Gee, I was expecting a classic Jobst tongue lashing (well deserved in
this case). A kindler, gentler Jobst? RB* will never be the same!
Mark_Atano...@REMOVEemail.sps.mot.com
Remove "REMOVE"
Thomas H. Kunich
In article <5lj6k9$m...@hplms2.hpl.hp.com>,
Jobst Brandt <jbr...@hpl.hp.com> wrote:
>We are working on
>a new Cyclometer that I think will make a lot of riders happy.
Hmm, I want the truely accurate non-bounce reading from the coil
input yet with great battery life. I want the offset bracket so that
the computer isn't in the way of my hands on a climb. I want automatic
start/stop but you might also make a touring model that calculates average
speed from a trigger to a trigger so that you can start the thing in the
morning and turn if off at the end of your days journey for those
number freaks who just have to know their average speed on a long
trip including stops. I want EASY reseting, not this pushing just
the right set of button while in just the correct mode.
And I want it cheap.
I'll take a dozen.
Kevin L. Papendick
Jobst Brandt wrote:
>
> change in management. I expect good things coming. We are working on
> a new Cyclometer that I think will make a lot of riders happy.
>
Don't tell me that! My new 45tt should be here on Tuesday or Wednesday.
--
Kevin L. Papendick
pape...@research.moore.com
Moore Pressure Sensitive Systems
Grand Island, NY USA
THolland63
Traction aside, I find the real advantage to slicks in the wet is that
they pick up and throw less water and grit. Ride behind one and you'll be
thankful for the smaller rooster tail. Not only does this make you less
messy, but less energy is wasted slinging all that water, so you will be
faster a well. Slick . . .
TRH
Jobst Brandt
Tom Holland63 writes:
> Traction aside, I find the real advantage to slicks in the wet is
> that they pick up and throw less water and grit. Ride behind one
> and you'll be thankful for the smaller rooster tail.
I think that was the first thing I noticed, years ago, when I switched
from a clunk with mini-automobile tread to a good bike with tubulars.
I no longer got water in the face from an uncovered front tire, and a
lot less spray up my back. I still often hear from people with
conventional tread complain of water in the face from their own bike
without mudgaurds.
Jobst Brandt <jbr...@hpl.hp.com>
Mike Ellwood
For a given type of tyre (let's say slicks), is it necessarily
true that a skinny tyre will have less traction/grip than a
fatter tyre? (assuming we're talking about the same wheel diameter).
Jobst Brandt
Mike Ellwood writes:
Yes. One main reason is that a smaller slick spot, one that has less
adhesion than the average of the road, will cause a slip at the
otherwise safe lean angle. Side slips on a two wheeled vehicle are
not recoverable on pavement, unless substantially better traction is
reached before ground is lost. That is to say, the lean angle worsens
rapidly and if you were at the limit before, you are beyond it once
you slip.
Beyond that, shear loading of the tread is lower with a fatter tire so
breakout will not leave a perceptible skid mark. If it leaves a skid
mark, then the stress concentration was such that the tread was over
stressed. A fat tire can also better absorb road surface irregularity
without making the bike bounce and lose traction.
Jobst Brandt <jbr...@hpl.hp.com>
Richard Young
On 21 May 1997 18:10:07 GMT, m...@unixfe.cc.rl.ac.uk (Mike Ellwood)
wrote:
>For a given type of tyre (let's say slicks), is it necessarily
>true that a skinny tyre will have less traction/grip than a
>fatter tyre? (assuming we're talking about the same wheel diameter).
>
--
No, A fatter tyre spreds the load which reduces the weight in a given
spot therefore reducing grip. Much the same as a stilleto heel or a
Doc Martin.
Rick
jts...@worldnet.att.net
Then why do GP motorcycle racers use the widest slicks they can fit on
their frames??
P.S. It's Marten
Chris Phillipo
In message <3390E7...@worldnet.att.net> - jts...@worldnet.att.net writes:
:>
:>Richard Young wrote:
:>>
:>> On 21 May 1997 18:10:07 GMT, m...@unixfe.cc.rl.ac.uk (Mike Ellwood)
:>> wrote:
:>>
:>> >For a given type of tyre (let's say slicks), is it necessarily
:>> >true that a skinny tyre will have less traction/grip than a
:>> >fatter tyre? (assuming we're talking about the same wheel diameter).
:>> >
:>> --
:>> No, A fatter tyre spreds the load which reduces the weight in a given
:>> spot therefore reducing grip. Much the same as a stilleto heel or a
:>> Doc Martin.
The coefficient of friction doesn't depend only on the downward force.
___________________________________________
Chris Phillipo - webm...@tread.pair.com
TREAD Publications
http://www.tread.pair.com
Jonathan M. Gladstone
> :>>
> :>> >For a given type of tyre (let's say slicks), is it necessarily
> :>> >true that a skinny tyre will have less traction/grip than a
> :>> >fatter tyre? (assuming we're talking about the same wheel
> diameter).
> :>> >
> :>> --
> :>> No, A fatter tyre spreds the load which reduces the weight in a
> given
> :>> spot therefore reducing grip. Much the same as a stilleto heel or
> a
> :>> Doc Martin.
> :>>
>
> The coefficient of friction doesn't depend only on the downward force.
>
>
The COEFFICIENT of friction is a function of the material(s) in
contact. The fricitonal FORCE is a function of the coefficient of
friction, the pressure, and the area of contact. In an ideal situation,
tire width shouldn't affect the frictional force, as a thinner tire will
have a smaller area, but more pressure. The total friction force should
just be Fs*A*P where Fs is the static coeffiecient of friction, A is the
Area of contact, and P is the pressure. Of course, P*A = F (the force,
or, in this case, the weight of the rider and cycle) so tired width is
irrelevant.
Again, this is just for an idealized situation. There are many other
effects of tire width, tread etc...perhaps someone else can comment on
those effects...
Jonathan M. Gladstone
Tom Ace
Jonathan M. Gladstone wrote:
[discussion about friction snipped]
> Again, this is just for an idealized situation. There are
> many other effects of tire width, tread etc...perhaps someone
> else can comment on those effects...
[Someone has to channel Jobst while he's not here.]
There is a Frequently Asked Questions list for bicycle newsgroups.
From said list:
------------------------------
Subject: 8.62 Rolling resistance of Tires
From: Jobst Brandt <jbr...@hplabsz.hpl.hp.com>
Date: Thu, 08 Aug 1996 17:17:57 PDT
The question often arises whether a small cross section tire has lower
rolling resistance than a larger one. The answer, as often, is yes
and no, because unseen factors come into play. Rolling resistance of
a tire arises almost entirely from flexural rubber losses in the tire
and tube. Rubber, especially with carbon black, as is commonly used in
tires, is a high loss material. On the other hand rubber without
carbon black although having lower losses, wears rapidly and has
miserable traction when wet.
Besides the tread, the tube of an inflated tire is so firmly pressed
against the casing that it, in effect, becomes an internal tread.
The tread and the tube together absorb the majority of the energy lost
in the rolling tire while the inter-cord binder (usually rubber) comes
in far behind. Tread scuffing on the road is even less significant.
Patterned treads measurably increase rolling resistance over slicks,
because the rubber bulges and deforms into tread voids when pressed
against the road. This effect, tread squirm, is mostly absent with
smooth tires because it cannot be bulge laterally by road contact
because rubber, although elastic, is incompressible.
Small cross section tires experience more deformation than a large
cross section tire and therefore, should have greater rolling
resistance, but they generally do not, because large and small cross
section tires are not identical in other respects. Large tires nearly
always have thicker tread and often use heavier tubes, besides having
thicker casings. For these reasons, smaller tire usually have lower
rolling resistance rather than from the smaller contact patch to which
it is often attributed.
These comparative values were measured on various tires over a range
of inflation pressures that were used to determine the response to
inflation. Cheap heavy tires gave the greatest improvement in rolling
resistance with increased pressure but were never as low as high
performance tires. High performance tires with thin sidewalls and
high TPI (threads per inch) were low in rolling resistance and
improved little with increasing inflation pressure.
As was mentioned in another item, tubular tires, although having lower
tire losses, performed worse than equivalent clincher tires because
the tubular's rim glue absorbs a constant amount of energy regardless
of inflation pressure. Only (hard) track glue absolves tubulars of
this deficit and should always be used in timed record events.
------------------------------