Remember the ads for the old Avocet smooth tires?
Bill
dry pavement than treaded tires. True or false?
How did the smooth tires do on wet pavement? How about on wet painted
pavement?
Remember the rider they showed in their ads who was leaning his road
bike on a downhill turn at (what seemed to me to be) a ridiculous
angle? Were those photos real or fake? Anybody know who the rider
was? He's got bigger ones than I've got!
Why did Avocet stop selling smooth tires? Lack of demand? Lawsuits?
Because they went out of business?
Inquiring minds want to know.
Art Harris
> They claimed that smooth tires actually gave you better traction on
> dry pavement than treaded tires. True or false?
>
True
> How did the smooth tires do on wet pavement? How about on wet painted
> pavement?
>
Better than those with tread patterns.
> Remember the rider they showed in their ads who was leaning his road
> bike on a downhill turn at (what seemed to me to be) a ridiculous
> angle? Were those photos real or fake? Anybody know who the rider
> was?
You're joking, right?
http://sheldonbrown.com/brandt/images/tiretest.jpg
>
> Why did Avocet stop selling smooth tires? Lack of demand? Lawsuits?
> Because they went out of business?
>
>
They were made by IRC in Japan, which had problems after shifting
production to Korea.
Art Harris
thirty-six
> They claimed that smooth tires actually gave you better traction on
> dry pavement than treaded tires. True or false?
How could you possibly sell a tire that actively slowed you down over
the regular version and then boasted about it?
> How did the smooth tires do on wet pavement? How about on wet painted
> pavement?
How do you expect? Seems to be the important question to many.
> Remember the rider they showed in their ads who was leaning his road
> bike on a downhill turn at (what seemed to me to be) a ridiculous
> angle? Were those photos real or fake? Anybody know who the rider
> was? He's got bigger ones than I've got!
It's only an image. A ridiculous size 15's, for a ridiculous rider, I
believe.
> Why did Avocet stop selling smooth tires? Lack of demand? Lawsuits?
> Because they went out of business?
Not enough buyers. One size fits all policy doesn't work for bicycle
tyres. Lack of proper distribution (UK).
Norman
Same reason Suntour, whose basic derailer design is
used by _everyone_, went under: Great engineering,
terrible marketing.
If you can't give away 2-3000 units to supply international
race teams and fill prize bins at more local races, and run
full page ads in every major industry magazine month after
month, and pay editors and writers at those same
magazines to write gushing reviews of your product, don't
even think about trying to compete with shimano.
Chalo
>
> They claimed that smooth tires actually gave you better traction on
> dry pavement than treaded tires. True or false?
True.
> How did the smooth tires do on wet pavement?
Fine.
> How about on wet painted pavement?
Fine.
The issue with smooth treads always comes down to loose solids between
tire and surface. Whether these solids are relatively large like pea
gravel, relatively small like sand, or truly tiny like soil particles
in the form of wet mud, they break the traction of a smooth tire very
effectively. Appropriately treaded tires have half a chance of
cutting through the loose material to get a purchase on something more
stable. It's not confidence-inspiring, but it's better than
nothing.
> Why did Avocet stop selling smooth tires? Lack of demand? Lawsuits?
> Because they went out of business?
Avocet made a couple of serious errors in distributing their tires to
retailers. They refused to have their tires distributed by others,
but they required shops to order $500 wholesale value of product,
minimum. That meant most independent shops couldn't be bothered, or
couldn't afford to stock them.
For all I know, Avocet tires may still be available technically, but I
know of no retail sellers for them.
Chalo
thirty-six
> Bill wrote:
>
> > They claimed that smooth tires actually gave you better traction on
> > dry pavement than treaded tires. True or false?
>
> True.
>
> > How did the smooth tires do on wet pavement?
>
> Fine.
>
> > How about on wet painted pavement?
>
> Fine.
Ha Ha, Ha Ha
>
> The issue with smooth treads always comes down to loose solids between
> tire and surface.
So make sure you only ride on a test track that has been detergent
cleaned and hot rinsed and you'll be alright.
> Whether these solids are relatively large like pea
> gravel, relatively small like sand, or truly tiny like soil particles
> in the form of wet mud, they break the traction of a smooth tire very
> effectively.
and oil.
> Appropriately treaded tires have half a chance
Much better than none.
Bill
bike on a downhill turn at (what seemed to me to be) a ridiculous
angle? Were those photos real or fake? Anybody know who the rider
was?
>
You're joking, right?
>
> http://sheldonbrown.com/brandt/images/tiretest.jpg
>
have somewhat larger ones than I've got. Ever since my last
experience with roadrash, I've been taking the turns pretty slowly.
Bill
retroguybilly
thirty-six
Just checked that photo, the lean looks less than 45deg, it even looks
that with modern pedals he could get the inside down on that corner.
M'bike riders can do a 55deg to 60deg lean on racing tyres in the
dry. With good wheel suspension I see this as a possibility with
bicycles.
Art Harris
>> You're joking, right?
>
> >http://sheldonbrown.com/brandt/images/tiretest.jpg
>
> No, Art, I'm not joking. Thanks for the link. Yeah, that guy does
> have somewhat larger ones than I've got. Ever since my last
> experience with roadrash, I've been taking the turns pretty slowly.
>
Well, the guy in the photo is Jobst Brandt who posts here often.
Art Harris
Frank Krygowski
> On 19 Nov, 07:28, Chalo <chalo.col...@gmail.com> wrote:
>
> > Bill wrote:
>
> > > They claimed that smooth tires actually gave you better traction on
> > > dry pavement than treaded tires. True or false?
>
> > True.
>
> > > How did the smooth tires do on wet pavement?
>
> > Fine.
>
> > > How about on wet painted pavement?
>
> > Fine.
>
> Ha Ha, Ha Ha
>
>
>
> > The issue with smooth treads always comes down to loose solids between
> > tire and surface.
>
> So make sure you only ride on a test track that has been detergent
> cleaned and hot rinsed and you'll be alright.
Oh please. I've ridden several sets of those Avocets until they've
worn out, on every sort of road imaginable. I don't corner the way
Jobst does in that photo, but their smooth rubber has always gripped
the road just fine. Those were my favorite tires.
- Frank Krygowski
Jobst Brandt
>>>> They claimed that smooth tires actually gave you better traction
>>>> on dry pavement than treaded tires. True or false?
>>> True.
>>>> How did the smooth tires do on wet pavement?
>>> Fine.
>>>> How about on wet painted pavement?
>>> Fine.
>> Ha Ha, Ha Ha
>>> The issue with smooth treads always comes down to loose solids
>>> between tire and surface.
>> So make sure you only ride on a test track that has been detergent
>> cleaned and hot rinsed and you'll be alright.
> Oh please. I've ridden several sets of those Avocets until they've
> worn out, on every sort of road imaginable. I don't corner the way
> Jobst does in that photo, but their smooth rubber has always gripped
> the road just fine.
It's too bad that van der Waals forces, the ones that describe
adhesion and lubrication, are not taught in physics courses. Most
people, including engineers, have no idea what makes things adhere or
stick, and what the boundary between lubrication and adhesion is for
liquids.
> Those were my favorite tires.
Mine too, until IRC got rid of their bicycle tire division to another
manufacturer, who had no idea of how to make them.
Jobst Brandt
Jobst Brandt
>>> They claimed that smooth tires actually gave you better traction
>>> on dry pavement than treaded tires. True or false?
>> How could you possibly sell a tire that actively slowed you down
>> over the regular version and then boasted about it?
>>> How did the smooth tires do on wet pavement? How about on wet
>>> painted pavement?
>> How do you expect? Seems to be the important question to many.
>>> Remember the rider they showed in their ads who was leaning his
>>> road bike on a downhill turn at (what seemed to me to be) a
>>> ridiculous angle? Were those photos real or fake? Anybody know
>>> who the rider was? He's got bigger ones than I've got!
>> It's only an image. A ridiculous size 15's, for a ridiculous
>> rider, I believe.
>>> Why did Avocet stop selling smooth tires? Lack of demand?
>>> Lawsuits? Because they went out of business?
>> Not enough buyers. One size fits all policy doesn't work for
>> bicycle tyres. Lack of proper distribution (UK).
> Same reason SunTour, whose basic derailleur design is used by
> _everyone_, went under: Great engineering, terrible marketing.
> If you can't give away 2-3000 units to supply international race
> teams and fill prize bins at more local races, and run full page ads
> in every major industry magazine month after month, and pay editors
> and writers at those same magazines to write gushing reviews of your
> product, don't even think about trying to compete with Shimano.
...and what would that do for the customer in the bicycle store? The
problem is the same for most goods today, which is IMAGE while and
function be damned. Just think how many riders need 33 different gear
combinations. When I consider how many thousands of miles on mountain
tours I rode on one chainring and a couple of sprockets on a five
speed cluster never feeling at a loss for gear ratios.
You could also ask that of Campagnolo, once the unchallenged leader in
bicycle components. Tullio Campagnolo retired along with his chief
engineer, and we never saw components as elegantly designed and
manufactured again as the old stuff. That's where Masi, Cinelli,
Colnago, and most others went. The undiscerning public deserves what
they buy.
Iv'e watched the displays at InterBike international bicycle trade
show for years and watched the technical content go to approximately
zero, where it arrived in this year's event. Fashion and image is what
sells.
So how shiny black and jacked up is the average driver's TRUCK these
days, as Mrs. houewife goes shopping and climbs down from the cab in
the supermarket parking lot?
Jobst Brandt
Simon Lewis
> Frank Krygowski wrote:
>
>>>>> They claimed that smooth tires actually gave you better traction
>>>>> on dry pavement than treaded tires. True or false?
>
>>>> True.
>
>>>>> How did the smooth tires do on wet pavement?
>
>>>> Fine.
>
>>>>> How about on wet painted pavement?
>
>>>> Fine.
>
>>> Ha Ha, Ha Ha
>
>>>> The issue with smooth treads always comes down to loose solids
>>>> between tire and surface.
>
>>> So make sure you only ride on a test track that has been detergent
>>> cleaned and hot rinsed and you'll be alright.
>
>> Oh please. I've ridden several sets of those Avocets until they've
>> worn out, on every sort of road imaginable. I don't corner the way
>> Jobst does in that photo, but their smooth rubber has always gripped
>> the road just fine.
>
> It's too bad that van der Waals forces, the ones that describe
> adhesion and lubrication, are not taught in physics courses. Most
> people, including engineers, have no idea what makes things adhere or
> stick, and what the boundary between lubrication and adhesion is for
> liquids.
All I know is this : slicks in wet "in town" cycling are a recipe for a
spill. End of subject.
>
>> Those were my favorite tires.
>
> Mine too, until IRC got rid of their bicycle tire division to another
> manufacturer, who had no idea of how to make them.
>
> Jobst Brandt
Sure. Of course these tyre specialists had no idea.
Jobst Brandt
>>>>>> They claimed that smooth tires actually gave you better traction
>>>>>> on dry pavement than treaded tires. True or false?
>>>>> True.
>>>>>> How did the smooth tires do on wet pavement?
>>>>> Fine.
>>>>>> How about on wet painted pavement?
>>>>> Fine.
>>>> Ha Ha, Ha Ha
>>>>> The issue with smooth treads always comes down to loose solids
>>>>> between tire and surface.
>>>> So make sure you only ride on a test track that has been detergent
>>>> cleaned and hot rinsed and you'll be alright.
>>> Oh please. I've ridden several sets of those Avocets until they've
>>> worn out, on every sort of road imaginable. I don't corner the way
>>> Jobst does in that photo, but their smooth rubber has always gripped
>>> the road just fine.
>> It's too bad that van der Waals forces, the ones that describe
>> adhesion and lubrication, are not taught in physics courses. Most
>> people, including engineers, have no idea what makes things adhere or
>> stick, and what the boundary between lubrication and adhesion is for
>> liquids.
> All I know is this : slicks in wet "in town" cycling are a recipe for a
> spill. End of subject.
That may be your perception, but I have ridden smooth tires for many
years on wet and dry roads and still do with Continental GatorSkins:
As I said, you should become familiar with van der Waals thesis on
adhesion.
>>> Those were my favorite tires.
>> Mine too, until IRC got rid of their bicycle tire division to another
>> manufacturer, who had no idea of how to make them.
> Sure. Of course these tyre specialists had no idea.
No idea of WHAT? I suspect you are talking of folklore rather than
practical tests. Do you wear waffle stompers to walk down the road
when it rains for the traction you perceive:
Jobst Brandt
Norman
I apologise for not falling down every single time I go out
in the snow, rain, sleet, ice on slick tires. Lord knows
how lucky I am!
>
> >> Those were my favorite tires.
>
> > Mine too, until IRC got rid of their bicycle tire division to another
> > manufacturer, who had no idea of how to make them.
>
> Sure. Of course these tyre specialists had no idea.
Ac japeres and jangeleres, Judas children,
Feynen hem fantasies, and fooles hem maketh -
And hen wit at wille to werken if they wolde.
--Wm. Langland
thirty-six
>, on every sort of road imaginable. I don't corner the way
> Jobst does in that photo, but their smooth rubber has always gripped
> the road just fine. Those were my favorite tires.
So, cornering on wet polished granite setts? Riding along a cobbled
road? Turning across rail tracks? A loose stone bridleway? A
packhorse trail? You done these?
Simon Lewis
You're obviously a cycling alpha male.
>
>>
>> >> Those were my favorite tires.
>>
>> > Mine too, until IRC got rid of their bicycle tire division to another
>> > manufacturer, who had no idea of how to make them.
>>
>> Sure. Of course these tyre specialists had no idea.
>
> Ac japeres and jangeleres, Judas children,
> Feynen hem fantasies, and fooles hem maketh -
> And hen wit at wille to werken if they wolde.
> --Wm. Langland
Wonderful I am sure.
But in the meantime in the real world .....
Simon Lewis
Mounting curbs wet on pavements, drainage gratings etc.
Like the helmet naysayers these guys appear to inhabit some mythical
universe where only they can see the one truth.
Norman
I'm very sorry. Do you need me to translate it into
monosyllables, or will just sayin', "Uh, USA USA!"
work for you? Seriously: what part of Alabama
did you grow up in to have received such a poor
education?
Simon Lewis
What are you talking about? You seem to be raving for some reason.
Translate what into monosyllables?
Frank Krygowski
> spill. End of subject.
End of subject for those who don't want to think, or examine actual
experience.
My spill count on Avocets is zero. That includes wet, in town, out of
town, rough roads, smooth roads, gravel roads, paint stripes and all
the rest in every possible combination.
Get a grip.
- Frank Krygowski
Frank Krygowski
Perhaps not the "wet polished granite setts." But one stretch of
street I sometimes ride is ancient, lumpy brick that's probably not
much different. (And AFAIK, cobbles and setts are synomyms.)
Railroad tracks, gravel, dirt - yes, I've done those. I ride mostly
pavement, but when necessary or desirable, I ride whatever I need to.
Would you really instantaneously fall if your tires didn't have
tread? Are you admitting to so much lesser competence?
- Frank Krygowski
thirty-six
> On Nov 19, 2:56 pm, thirty-six <thirty-...@live.co.uk> wrote:
>
> > On 19 Nov, 18:01, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > >, on every sort of road imaginable. I don't corner the way
> > > Jobst does in that photo, but their smooth rubber has always gripped
> > > the road just fine. Those were my favorite tires.
>
> > So, cornering on wet polished granite setts? Riding along a cobbled
> > road? Turning across rail tracks? A loose stone bridleway? A
> > packhorse trail? You done these?
>
> Perhaps not the "wet polished granite setts." But one stretch of
> street I sometimes ride is ancient, lumpy brick that's probably not
> much different. (And AFAIK, cobbles and setts are synomyms.)
No they're not. Cobbles are what you find in rivers, rounded
polished stones. There were set dimensions (7"x5"x4" or something
like that) which were used to select the cobbles for road laying. A
granite sett road has little texture, the setts are on end and square
in section, to find such a road in good condition is wonderous for the
cyclist as all tread noise seems to disappear and there is no
vibration to feel of. There was one in perfect condition I used
regularly up to a decade ago but has since been covered. Perfect when
dry, but required caution when cornering in the wet. I used this road
to assess a tyres grip in the wet before attempting high speed
cornering on grippier surfaces. I'd average about three tyres a year
when racing and although I never tried the Fasgrip, one was obtained
by a club rider and it was tried by other members of the club. It did
not get a favourable respose. For high pressures, Michelins and
Hutchinsons became the order of the day. There were many brands and
models being sampled at one time. My testing on the granite along
with less shock transmission on rough finished roads had me settle on
the Hutchinsons. We mixed with the other clubs in the district and
could draw on the opinions of 200 or so riders over a weekend which
included tourist and racing riders. It was a time when the touring
tubular was getting difficult to get hold of so a lot of tourists were
trying High pressures and when the racers saw how well the tourists
were riding they wanted to know more about the tyres. Avocets were
not popular, this was not just ma marketing problem, because as I've
said we, the racers would swap tyres to see the differences in feel
and wet cornering, and also hill climbing.
> Railroad tracks, gravel, dirt - yes, I've done those. I ride mostly
> pavement, but when necessary or desirable, I ride whatever I need to.
If you corner on a wet railtrack (try to) you'll be on your arse if
you're using slicks.
>
> Would you really instantaneously fall if your tires didn't have
> tread? Are you admitting to so much lesser competence?
I'm competent to recognise not to ride a tyre without tread. When the
tread has gone I've always thrown my tyres away.
Frank Krygowski
>
> ... although I never tried the Fasgrip, one was obtained
> by a club rider and it was tried by other members of the club. It did
> not popular, this was not just ma marketing problem, because as I've
> said we, the racers would swap tyres to see the differences in feel
> and wet cornering, and also hill climbing.
I know this will shock and enrage some, but I've never accepted the
idea that the "feelings" of racers constitute proof.
> > Railroad tracks, gravel, dirt - yes, I've done those. I ride mostly
> > pavement, but when necessary or desirable, I ride whatever I need to.
>
> If you corner on a wet railtrack (try to) you'll be on your arse if
> you're using slicks.
I clearly recall seeing two different cyclists crash while crossing
wet railroad tracks. Both were using bike tires with tread.
Also, one of only two motorcycle falls I've ever experienced involved
a turn on a set of wet railroad tracks. Fortunately both of my two
falls were at walking speed. But those motorcycle tires also featured
a definite tread pattern.
So I'd say if you try to corner too fast on wet steel, tread or no
tread, you'll be on your arse. And I don't believe the tread is going
to make a measurable difference.
> I'm competent to recognise not to ride a tyre without tread.
> When the tread has gone I've always thrown my tyres away.
Have you never ridden tires with fine "file" tread? Do you really
throw them out after a few hundred miles? If so, can I have them?
- Frank Krygowski
Jobst Brandt
>> ... although I never tried the Fasgrip, one was obtained by a club
>> rider and it was tried by other members of the club. It did not
>> get a favourable response. ... Avocets were not popular, this was
>> not just ma marketing problem, because as I've said we, the racers
>> would swap tyres to see the differences in feel and wet cornering,
>> and also hill climbing.
> I know this will shock and enrage some, but I've never accepted the
> idea that the "feelings" of racers constitute proof.
>>> Railroad tracks, gravel, dirt - yes, I've done those. I ride
>>> mostly pavement, but when necessary or desirable, I ride whatever
>>> I need to.
>> If you corner on a wet railway track (try to) you'll be on your ass if
>> you're using slicks.
> I clearly recall seeing two different cyclists crash while crossing
> wet railroad tracks. Both were using bike tires with tread.
> Also, one of only two motorcycle falls I've ever experienced
> involved a turn on a set of wet railroad tracks. Fortunately both
> of my two falls were at walking speed. But those motorcycle tires
> also featured a definite tread pattern.
> So I'd say if you try to corner too fast on wet steel, tread or no
> tread, you'll be on your ass. And I don't believe the tread is
> going to make a measurable difference.
>> I'm competent to recognise not to ride a tyre without tread. When
>> the tread has gone I've always thrown my tyres away.
> Have you never ridden tires with fine "file" tread? Do you really
> throw them out after a few hundred miles? If so, can I have them?
As I have often mentioned in this forum, tire traction on hard
surfaces is not dependent on tread profile... except to get worse with
greater depth of profile (as with knobby tires and grooves). A
knobby MTB tire will slide as well as any tire on smooth metal or
other such material.
Traction on hard surface arises from micro-granular structure of the
surface, such as small paving stones in asphalt or concrete. It does
not come from tire tread patterns. If you don't believe that you
should not fly with commercial air whose tires are large slicks that
touch down with as much as 200mph with hard braking in the rain.
Jobst Brandt
Simon Lewis
In a straight line with no lean on a flat hard specially made and clean
runway.
Are you really this far from reality?
>
> Jobst Brandt
Chalo
>
> Chalo wrote:
> >
> > Whether these solids are relatively large like pea
> > gravel, relatively small like sand, or truly tiny like soil particles
> > in the form of wet mud, they break the traction of a smooth tire very
> > effectively.
>
> and oil.
Oil does the job on any tire regardless of tread. Same with fine silt
or clay, algal slime, and smooth ice. Tire tread edges can't cut
through these things to an underlying surface, so tread pattern does
not help.
Chalo
Simon Lewis
thirty-six
> I know this will shock and enrage some, but I've never accepted the
> idea that the "feelings" of racers constitute proof.
Feel as in security, as in comfort, as in fatigue inducing level.
This is entirely subjective and individual, but with enough testers a
good approximation of how the tyre will perform for oneself can be
assertained.
> I clearly recall seeing two different cyclists crash while crossing
> wet railroad tracks. Both were using bike tires with tread.
That will always happen with smooth treads. Non-recoverable side
slip.
> Also, one of only two motorcycle falls I've ever experienced involved
> a turn on a set of wet railroad tracks. Fortunately both of my two
> falls were at walking speed. But those motorcycle tires also featured
> a definite tread pattern.
The precise compound, vulcanization exposure and age of the tyre will
all affect the grip. You have to get these right first.
> So I'd say if you try to corner too fast on wet steel, tread or no
> tread, you'll be on your arse. And I don't believe the tread is going
> to make a measurable difference.
It will if it ihas a fine herringbone pattern. The difference is
measurable in the absence of a bruise.
> > I'm competent to recognise not to ride a tyre without tread.
> > When the tread has gone I've always thrown my tyres away.
>
> Have you never ridden tires with fine "file" tread? Do you really
> throw them out after a few hundred miles? If so, can I have them?
They dont wear that quick. It takes around two thousand miles to wear
the centre section sufficientlty to reduce cornering grip to that of a
slick. Tubular tyres fare better. No wear evident for a thousand
miles, possibly half worn the centre pattern at 4-5k miles.
thirty-six
> As I have often mentioned in this forum, tire traction on hard
> surfaces is not dependent on tread profile... except to get worse with
> greater depth of profile (as with knobby tires and grooves). A
> knobby MTB tire will slide as well as any tire on smooth metal or
> other such material.
I'm not discussing agressive off-road tread meant for soft dirt and
awkward pedalling.
The discussion is about road tyres on wet smooth train tracks. If
there is no texture to the road surface the tyre needs texture to
permit the contact of rubber with road. otherwise the tyre sits on
top until the water disperses sidewaysthrough the tiny gap between
tyre and road.
>
> Traction on hard surface arises from micro-granular structure of the
> surface, such as small paving stones in asphalt or concrete. It does
> not come from tire tread patterns. If you don't believe that you
> should not fly with commercial air whose tires are large slicks that
> touch down with as much as 200mph with hard braking in the rain.
Airstrips are constantly checked for grip, roads are not tested to the
same standards or anywhere near as frequently. Cars and bicycles do
not have air braking or any aerofail stabilization like aircraft.
Pilots will lock up landing gear and slide the wheels and will use the
rudder to stabilize the aircraft. Bicycles do not as a general rule
travel in excess of 40mph so a carrying suitable tailplane because of
using slicks is wasteful.
thirty-six
> Jobst Brandt <jbra...@sonic.net> writes:
is as high as a kite.
thirty-six
Yes they can, you just need a stiffer and smaller contact area
resulting in a higher penetration pressure. This is why metal studs
work on ice, the higher pressure permits penetration. I have noticed
great differences in adhesion through algae. But it's water on smooth
surfaces we are discussing which can be solved by rubber.
Peter Rathmann
> On 20 Nov, 03:39, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > I clearly recall seeing two different cyclists crash while crossing
> > wet railroad tracks. Both were using bike tires with tread.
>
> That will always happen with smooth treads. Non-recoverable side
> slip.
And with any other type of tread.
> > So I'd say if you try to corner too fast on wet steel, tread or no
> > tread, you'll be on your arse. And I don't believe the tread is going
> > to make a measurable difference.
>
> It will if it ihas a fine herringbone pattern. The difference is
> measurable in the absence of a bruise.
So please let us in on any such measurements that show a difference.
I've seen people slide out on wet tracks regardless of tire type. A
friend of mine has been sidelined from cycling for the last year
because of such an incident and his tires had the 'fine herringbone
pattern' that you advocate. Rubber on wet steel is not a good
combination and the only way to avoid problems is to keep sidewards
forces extremely low.
Frank Krygowski
> On 20 Nov, 03:39, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > I know this will shock and enrage some, but I've never accepted the
> > idea that the "feelings" of racers constitute proof.
>
> Feel as in security, as in comfort, as in fatigue inducing level.
> This is entirely subjective and individual, but with enough testers a
> good approximation of how the tyre will perform for oneself can be
> assertained.
Feel as in _whatever_. There are "expert" connoisseurs who claim
their finely developed senses can spot quality differences in wines,
in bicycle frames, in high quality stereo systems, in the sound
quality of fine violins, in abstract art and in many other fields.
But in each of those cases listed, those "experts" have failed when
subjected to blind tests.
> > I clearly recall seeing two different cyclists crash while crossing
> > wet railroad tracks. Both were using bike tires with tread.
>
> That will always happen with smooth treads. Non-recoverable side
> slip.
"Always"? Do you seriously think that nobody has ever made it across
wet railroad tracks on an Avocet tire??
> > So I'd say if you try to corner too fast on wet steel, tread or no
> > tread, you'll be on your arse. And I don't believe the tread is going
> > to make a measurable difference.
>
> It will if it ihas a fine herringbone pattern. The difference is
> measurable in the absence of a bruise.
That's an assertion stated with no logical explanation and no hint of
proof.
> > Have you never ridden tires with fine "file" tread? Do you really
> > throw them out after a few hundred miles? If so, can I have them?
>
> They dont wear that quick. It takes around two thousand miles to wear
> the centre section sufficientlty to reduce cornering grip to that of a
> slick.
Well, not in my experience. But no matter. At the first instant your
fine file treads wear down, please mail me your tires for
safekeeping. It's for your own protection. You can't be too safe,
you know! ;-)
- Frank Krygowski
Jobst Brandt
>>>> Whether these solids are relatively large like pea gravel,
>>>> relatively small like sand, or truly tiny like soil particles in
>>>> the form of wet mud, they break the traction of a smooth tire very
>>>> effectively.
>>> and oil.
>> Oil does the job on any tire regardless of tread. Same with fine
>> silt or clay, algal slime, and smooth ice. Tire tread edges can't
>> cut through these things to an underlying surface, so tread pattern
>> does not help.
> Yes they can, you just need a stiffer and smaller contact area
> resulting in a higher penetration pressure. This is why metal studs
> work on ice, the higher pressure permits penetration. I have
> noticed great differences in adhesion through algae. But it's water
> on smooth surfaces we are discussing which can be solved by rubber.
I don't see where this explains (slick) commercial aircraft tires.
Don't make this up on the fly. RR Locomotives get wheel spin on wet
and well worn steel rails. They all use sand to control slip. There
is more pressure there than with any non-metallic wheel offers.
Tribology is a greatly misunderstood subject. From what you write, I
doubt that you understand physics or mechanics of materials.
Jobst Brandt
Jobst Brandt
>>>> Whether these solids are relatively large like pea gravel,
>>>> relatively small like sand, or truly tiny like soil particles in
>>>> the form of wet mud, they break the traction of a smooth tire very
>>>> effectively.
>>> and oil.
>> Oil does the job on any tire regardless of tread. Same with fine
>> silt or clay, algal slime, and smooth ice. Tire tread edges can't
>> cut through these things to an underlying surface, so tread pattern
>> does not help.
> Yes they can, you just need a stiffer and smaller contact area
> resulting in a higher penetration pressure. This is why metal studs
> work on ice, the higher pressure permits penetration. I have
> noticed great differences in adhesion through algae. But it's water
> on smooth surfaces we are discussing which can be solved by rubber.
I don't see where this explains (slick) commercial aircraft tires.
Don't make this up on the fly. RR Locomotives get wheel spin on wet
and well worn steel rails. They all use sand to control slip. There
is more pressure there than any non-metallic wheel offers. Tribology
Don Piven
> Pilots will lock up landing gear and slide the wheels and will use the
> rudder to stabilize the aircraft.
'Scuse me, but that statement is high-volume bull exhaust. If you lock
up the wheels on a landing, the rudder will only control which way the
nose points, not which way the airplane moves. This is why commercial
airplanes have antiskid braking systems. This is also why cars have
anti-lock braking systems, to keep the driver from locking the wheels
and losing control over the car in a skid situation.
thirty-six
If the pilot didn't control the aircraft with the rudder, it would
still skew and stick a wing tip in the ground.
Don Piven
> If the pilot didn't control the aircraft with the rudder, it would
> still skew and stick a wing tip in the ground.
If the pilot is worried about sticking his wingtip in the ground, he'd
use his ailerons (which control roll) instead of his rudder (which
controls yaw).
A competent pilot would release the brakes, get the wheels gripping the
runway again, and then reapply the brakes to get his plane under
control, before thinking of goofy stunts like using his attitude
controls. Jobst's point was that it's nearly unheard of for aircraft
tires to lose traction even while being heavily braked at high speed
(discounting bad braking efficiency, which is a property of the runway),
and I was commenting about your silly proposition that pilots lock up
their wheels on purpose so they can control their craft with their
attitude control surfaces.
thirty-six
> On Nov 20, 8:15 am, thirty-six <thirty-...@live.co.uk> wrote:
>
> > On 20 Nov, 03:39, Frank Krygowski <frkry...@gmail.com> wrote:
>
> > > I know this will shock and enrage some, but I've never accepted the
> > > idea that the "feelings" of racers constitute proof.
>
> > Feel as in security, as in comfort, as in fatigue inducing level.
> > This is entirely subjective and individual, but with enough testers a
> > good approximation of how the tyre will perform for oneself can be
> > assertained.
>
> Feel as in _whatever_. There are "expert" connoisseurs who claim
> their finely developed senses can spot quality differences in wines,
> in bicycle frames, in high quality stereo systems, in the sound
> quality of fine violins, in abstract art and in many other fields.
> But in each of those cases listed, those "experts" have failed when
> subjected to blind tests.
Taste and auditory response are subjective and most subjective tests
applied are irrelevant for they fail to address the non-linearity of
auditory and taste reponses. Flavour response may be tainted by
experience and what is comforting to one is not to another. Tyres are
relatively simple to assess, ride the same roads and see if you ride
them quicker with less effort and resultant fatigue, if so, it's a
better tyre, tell team nmates.
>
> > > I clearly recall seeing two different cyclists crash while crossing
> > > wet railroad tracks. Both were using bike tires with tread.
>
> > That will always happen with smooth treads. Non-recoverable side
> > slip.
>
> "Always"? Do you seriously think that nobody has ever made it across
> wet railroad tracks on an Avocet tire??
Not if they were trying to corner at the same time. Patterned treads
will help although cornering power is still much reduced.
>
> > > So I'd say if you try to corner too fast on wet steel, tread or no
> > > tread, you'll be on your arse. And I don't believe the tread is going
> > > to make a measurable difference.
>
> > It will if it ihas a fine herringbone pattern. The difference is
> > measurable in the absence of a bruise.
>
> That's an assertion stated with no logical explanation and no hint of
> proof.
If you dont fall on your arse, like you would if you attempted to take
a bend across tracks with a slick tyresuch as an avocet, then you dont
get the 1.1/2DIA bruise which shows up the next day.
>
> > > Have you never ridden tires with fine "file" tread? Do you really
> > > throw them out after a few hundred miles? If so, can I have them?
>
> > They dont wear that quick. It takes around two thousand miles to wear
> > the centre section sufficientlty to reduce cornering grip to that of a
> > slick.
>
> Well, not in my experience. But no matter. At the first instant your
> fine file treads wear down, please mail me your tires for
> safekeeping. It's for your own protection. You can't be too safe,
> you know! ;-)
>
No chance, I've improved my training tubs with the herringbone pattern
and hope to retread them when wearing thin, because they ride so
well. These were very good tyres when bought, they are better now and
I may even put some thin strips on them and see if they perform on the
track with one of the club youngsters..
thirty-six
> nameless from the UK wrote:
>
> >>>> Whether these solids are relatively large like pea gravel,
> >>>> relatively small like sand, or truly tiny like soil particles in
> >>>> the form of wet mud, they break the traction of a smooth tire very
> >>>> effectively.
> >>> and oil.
> >> Oil does the job on any tire regardless of tread. Same with fine
> >> silt or clay, algal slime, and smooth ice. Tire tread edges can't
> >> cut through these things to an underlying surface, so tread pattern
> >> does not help.
> > Yes they can, you just need a stiffer and smaller contact area
> > resulting in a higher penetration pressure. This is why metal studs
> > work on ice, the higher pressure permits penetration. I have
> > noticed great differences in adhesion through algae. But it's water
> > on smooth surfaces we are discussing which can be solved by rubber.
>
> I don't see where this explains (slick) commercial aircraft tires.
No, this is a bicyle tyre discussion about bicycle tyres in a bicycle
newsgroup in which talk about bicycles occurs. I'd have thought that
after thirty years you cou;ld have at least fixed that one in your
mind.
>
> Don't make this up on the fly.
I know you dont, the same documents you used over ten years ago keep
re-appearing, you're well practised and have an extensive library of
persuasive arguments which dont apply to bicycle usage and are a
complete sideswipe to divert attention that you are consistently
wrong.
Such as:
> RR Locomotives get wheel spin on wet
> and well worn steel rails. They all use sand to control slip. There
> is more pressure there than with any non-metallic wheel offers.
> Tribology is a greatly misunderstood subject. From what you write, I
> doubt that you understand physics or mechanics of materials.
Where have I heard that before?
thirty-six
With large aicraft, wheel brakes have to be used. It is diparity in
braking, which could be caused in the braking system or the airstrip,
which causes the plane to yaw, the roll comes as a result of it. If
the pilot leaves of the brakes he runs off the end of the airstrip
which is not tooo comfortable. By controlling the yaw with the rudder
the plane does not roll and it tracks straight along the runway.
Using the ailerons will be too late and the plane will skew off the
runway before tipping the outer wing into the turf.
Gary Mishler
"thirty-six" <thirt...@live.co.uk> wrote in message
news:4fba5ee2-543f-4da7...@m16g2000yqc.googlegroups.com...
>>Pilots will lock up landing gear and slide the wheels and will use the
>>rudder to stabilize the aircraft.
Not to start 'Thread creep", but this statement is not even close to
correct.
Mish
thirty-six
> Tyres work like squeegees. Having a cosmetic pattern on the surface
> is more likely to interfere with that than to enhance it.
You could 0only use that analogy to a sliding tyre with a sharp
patterned tread perpendicular to the undesirable sliding motion. This
is why tyres did come with concentric rings. I did use some and the
rear tyre which was well worn was the one which slid out not the front
which maintained its pattern.>
>
> >> Traction on hard surface arises from micro-granular structure of the
> >> surface, such as small paving stones in asphalt or concrete. It does
> >> not come from tire tread patterns. If you don't believe that you
> >> should not fly with commercial air whose tires are large slicks that
> >> touch down with as much as 200mph with hard braking in the rain.
>
> >Airstrips are constantly checked for grip, roads are not tested to the
> >same standards or anywhere near as frequently. Cars and bicycles do
> >not have air braking or any aerofail stabilization like aircraft.
> >Pilots will lock up landing gear and slide the wheels and will use the
> >rudder to stabilize the aircraft.
>
> Not if they want to stay employed they don't.
I didn't say it was intentional, but its usually better to do that
than run off the end of the strip, which will put it out of action
while the aircraft is recovered. Will not the aircraft operator then
be charged for closing the airport?
> Have you checked the cost of those tyres?
Not recently £30000 I think I remember for a jumbo. But the more you
buy, the cheaper they get ;-)
>
> > Bicycles do not as a general rule
> >travel in excess of 40mph so a carrying suitable tailplane because of
> >using slicks is wasteful.
>
> On a cycle, we don't need that - we just sit up.
That is usually a good way to limit speed on a moderate grade to
40mph. I generally dont bother, especially if I havn't put on a
windcheater. My patterned tyres grip better than other tyres
patterned or not but I also use a larger contact patc so that wil have
something to do with it. The only reason a slick can match a pattern
is because the area of the contact patch is the same and the slick
applies more rubber, but if the contact patch area is larger consiting
of varying pressure because of pattern, the treaded tyre is clearly
superior in practice.
Gary Mishler
>> I didn't say it was intentional, but its usually better to do that
>> than run off the end of the strip, which will put it out of action
>> while the aircraft is recovered. Will not the aircraft operator then
>> be charged for closing the airport?
Actually you have a lot better chance of running off the end of the runway
by locking up the brakes and skidding the tires than if the wheels are
allowed to remain rotating while under braking. That is the reason large
aircraft have automatic anti-skid protection and why in recent years cars
have anti-lock brakes.
Stopping distances increase dramatically in aircraft when the anti-skid is
inoperative vs. when it is operational.
Mish
thirty-six
> "thirty-six" <thirty-...@live.co.uk> wrote in message
Does the pilot still have to balance braking forces or is the whole
system automated?
Jobst Brandt
>>>> I didn't say it was intentional, but its usually better to do
>>>> that than run off the end of the strip, which will put it out of
>>>> action while the aircraft is recovered. Will not the aircraft
>>>> operator then be charged for closing the airport?
>> Actually you have a lot better chance of running off the end of the
>> runway by locking up the brakes and skidding the tires than if the
>> wheels are allowed to remain rotating while under braking. That is
>> the reason large aircraft have automatic anti-skid protection and
>> why in recent years cars have anti-lock brakes.
>> Stopping distances increase dramatically in aircraft when the
>> anti-skid is inoperative vs. when it is operational.
> Does the pilot still have to balance braking forces or is the whole
> system automated?
... as automated as the brakes on your car that are confronted by the
same challenges.
Jobst Brandt
thirty-six
Hydraluic brakes controlled by foot pedal with manifold powered servo
assist, 'gravity position' sensor biases braking to front as weight
transfers to front wheels due to braking. That is the only automatic,
front bias. I dont find it necessary to correct left/right braking
according to wind bias, the car does not have wings and tends not to
want to spin. Dont seem to get overheated brakes with brake fade
neither. This I believe is a particular problem with large commercial
aircraft, rather severe brake fade, or is that just in the movies?
Jym Dyer
> Well, the guy in the photo is Jobst Brandt who posts
> here often.
=v= That's all well and good, but what does he know about
bicycle wheels, anyway? Are we to believe that he's the
world's leading authority on them or something?
<_Jym_>
Gary Mishler
> Does the pilot still have to balance braking forces or is the whole
> system automated?
Totally automated. Wheel sensors on each wheel detect wheel speed. When a
sensor detects a wheel is locking up the anti-skid computer comands a servo
to release just enough hydraylic pressure to that individual wheel to allow
it to remain rotating. All four main (in the aircraft I fly) wheels could
potentially have different amounts of hydraulic pressure applied at any
given time to modulate that individual wheel brake.
When maximum braking is required the pilot is taught to just mash the brake
pedals as hard as possible and let the anti-skid "do it's thing" to achieve
maximum braking effort.
Gary Mishler
>>Hydraluic brakes controlled by foot pedal with manifold powered servo
assist, 'gravity position' sensor biases braking to front as weight
transfers to front wheels due to braking. That is the only automatic,
front bias. I dont find it necessary to correct left/right braking
according to wind bias, the car does not have wings and tends not to
want to spin. Dont seem to get overheated brakes with brake fade
neither. This I believe is a particular problem with large commercial
aircraft, rather severe brake fade, or is that just in the movies? <<
It's a movie thing.
Aircraft are designed and certified to have "maximum stop braking effort"
without fade available for an aborted take-off at maximum take-off weight
and speed. Note that this certification requirement assumes operating
anti-skid system. If the anti-skid is inoperative then you are a test
pilot, and your test is pretty much guaranteed not to go well. :)
Aircraft are susceptible to heat induced brake fade but that would only come
into play if, for example, a crew made a landing with high brake load and
then took off again within too short of a time to allow the brakes to cool.
Or, if a crew made an aborted take-off then taxied back right away for
another take-off, or if a pilot 'rode the brakes' during an extended taxi,
etc.
Mish
Jobst Brandt
>>>>>> I didn't say it was intentional, but its usually better to do
>>>>>> that than run off the end of the strip, which will put it out
>>>>>> of action while the aircraft is recovered. Will not the
>>>>>> aircraft operator then be charged for closing the airport?
>>>> Actually you have a lot better chance of running off the end of
>>>> the runway by locking up the brakes and skidding the tires than
>>>> if the wheels are allowed to remain rotating while under
>>>> braking. That is the reason large aircraft have automatic
>>>> anti-skid protection and why in recent years cars have anti-lock
>>>> brakes. Stopping distances increase dramatically in aircraft
>>>> when the anti-skid is inoperative vs. when it is operational.
>>> Does the pilot still have to balance braking forces or is the
>>> whole system automated?
>> ... as automated as the brakes on your car that are confronted by
>> the same challenges.
> Hydraluic brakes controlled by foot pedal with manifold powered
> servo assist, 'gravity position' sensor biases braking to front as
> weight transfers to front wheels due to braking. That is the only
> automatic, front bias. I dont find it necessary to correct
> left/right braking according to wind bias, the car does not have
> wings and tends not to want to spin. Dont seem to get overheated
> brakes with brake fade neither. This I believe is a particular
> problem with large commercial aircraft, rather severe brake fade, or
> is that just in the movies?
Brake fade is something left behind when disk brakes took over. Brake
fade is loss of servo effect in leading shoe drum brakes. The
"leading shoe" term makes clear that these brakes depended on self
servo effect that is highly sensitive to friction coefficient of the
friction material. For this reason drum brakes are no longer used for
braking on vehicles... except on some large semi-trailer trucks
(mainly the trailers) that cannot accommodate disks suitably large to
dissipate heat.
"Brake fade" is a term left over from earlier times.
Jobst Brandt
Tom Sherman °_°
We have several different makes and models of pick-up trucks at work,
all less than 3 years old, and all have rear drum brakes, as does my
2005 Honda Civic. None are "grabby" they way older drum brakes used to
be (I used to drive a 1994 C/K 2500 that was particularly bad that way).
--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
Simon Lewis
> thirty-six <thirt...@live.co.uk> considered Fri, 20 Nov 2009
> 05:29:13 -0800 (PST) the perfect time to write:
>
>>On 20 Nov, 05:47, Jobst Brandt <jbra...@sonic.net> wrote:
>>
>>> As I have often mentioned in this forum, tire traction on hard
>>> surfaces is not dependent on tread profile... except to get worse with
>>> greater depth of profile (as with knobby tires and grooves). A
>>> knobby MTB tire will slide as well as any tire on smooth metal or
>>> other such material.
>>
>>I'm not discussing agressive off-road tread meant for soft dirt and
>>awkward pedalling.
>>The discussion is about road tyres on wet smooth train tracks. If
>>there is no texture to the road surface the tyre needs texture to
>>permit the contact of rubber with road. otherwise the tyre sits on
>>top until the water disperses sidewaysthrough the tiny gap between
>>tyre and road.
>
> Tyres work like squeegees. Having a cosmetic pattern on the surface
> is more likely to interfere with that than to enhance it.
To take the extreme this must be why motorcross bikes use slicks eh?
Stop talking so much nonsense.
thirty-six
<twshermanREM...@THISsouthslope.net> wrote:
>
> We have several different makes and models of pick-up trucks at work,
> all less than 3 years old, and all have rear drum brakes, as does my
> 2005 Honda Civic. None are "grabby" they way older drum brakes used to
> be (I used to drive a 1994 C/K 2500 that was particularly bad that way).
That'll be the er, negative servo reactionary force caused by er, the
other way roud, and coupled to the er, vacuum assisted hydraulic
master cylinder.
Don Piven
> We have several different makes and models of pick-up trucks at work,
> all less than 3 years old, and all have rear drum brakes, as does my
> 2005 Honda Civic. None are "grabby" they way older drum brakes used to
> be (I used to drive a 1994 C/K 2500 that was particularly bad that way).
Of course you realize that most of the braking force is applied by the
front (disc) brakes :-)
Jobst Brandt
You didn't say why. The drum brakes are for parking and hand brake
effectiveness, while the disks do speed control and stopping.
Nothing new there.
Jobst Brandt
thirty-six
What I've heard beaten about the bush is that rear disc brakes can be
a liability and perform worse than drums because it is difficult to
get much heat in to them. Drums are consistent performers and using
rear discs is unecessary overkill which will result in poor
performance on a lightweight saloon car with public road use. I think
the only validity to them on a car is when it is used for towing
purposes.
landotter
> thirty-six <thirty-...@live.co.uk> writes:
> > On 19 Nov, 18:01, Frank Krygowski <frkry...@gmail.com> wrote:
> >>, on every sort of road imaginable. I don't corner the way
> >> Jobst does in that photo, but their smooth rubber has always gripped
> >> the road just fine. Those were my favorite tires.
>
> > So, cornering on wet polished granite setts? Riding along a cobbled
> > road? Turning across rail tracks? A loose stone bridleway? A
> > packhorse trail? You done these?
>
> Mounting curbs wet on pavements, drainage gratings etc.
>
> Like the helmet naysayers these guys appear to inhabit some mythical
> universe where only they can see the one truth.
OK, please present your evidence that treadless tires suffer traction
difficulties on cobbles. Also throw in that study showing the dramatic
decrease in Australian cycling related head injuries.
You seem to have a bias against fact and statistics.
FWIW, I ride cyclocross tires on the daily rider for the odd trail and
fire road. They're a speed liability on road, but seem to grip just
fine as my slicks.
Bill
Yes, I know that Jobst is a very prominent cyclist, but I'll compare
my devotion to the sport with his any day. Why, I've been a bike bum
my entire life when I could get away with it!
DougC
I think that most of the aircraft I've seen had /ribbed/ tread tires as
well, tho'. Mostly small to middlin' planes however. Not so much the
bigger stuff. The center goes slick when they wear a bit I guess.
-------
Apparently some of the bigger stuff is still using ribbed tires:
http://www.skycontrol.net/industry/newbow-aerospace-ltd-aircraft-tire-service-equipment-helps-world-airlines-reduce-operating-costs-and-overheads/
above made tiny:
http://tinyurl.com/yfokktf
It's my understanding that ribbed tires tend to track straighter than
slicks, or other tread styles. They only don't work well as driving wheels.
We note that board-track-era racers used ribbed tires when running on
the wooden tracks {even though slicks were easily obtainable) and farm
implement trailers (and aircraft!) still use ribbed tires today....
{as a matter of fact-ology,,,,, in my efforts at home-made tire
building, I took a survey of period board-track era photos of
motorcycles that I could find online, and even asked others for help. In
all the photos, NONE of the motorcycles was using slicks.
Not one single example.
The motorcycles on board tracks ALWAYS used the ribbed tires, and
motorcycles anywhere else always had treaded tires of some kind, in
every photo I could find.
Slick tires were available, they are shown in period car tire
advertisements--but no advertisement for motorcycle tires I have yet
found showed slicks}
~