tire pressure for slippery pavement

[Werehatrack]

On Wed, 08 Nov 2006 13:37:01 +0100, Roberto Divia
<[email protected]> wrote:

>Mike Jacoubowsky wrote:
>> This morning's regular Tuesday/Thursday-morning ride was memorable due to
>> some unexpected, and *very* slippery pavement. The fog had burned off some
>> time earlier, but there was something about what it left behind in a few
>> places that caused noticeable slipping (a bit of an uncomfortable feeling as
>> you're going through a corner in a downhill spint!).
>
>No idea about the original request. Just a word of caution. If you'll ever
>ride in France under wet conditions (rain, fog) avoid all road markings,
>zebra crossing included. They get as slippery as if they were covered in
>soap. The worse are the zebra crossing at the entry/exit from roundabouts,
>where leaning is unavoidable. One moment you are up and the next moment
>you ask yourself who knocked you over.

I think the same paint is used in places here in Texas; same problem,
and same results. I have encountered it with the paint used to stripe
the bike lane on to the edge of a major street.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[bill]

[email protected] wrote:

> Painted and epoxy applique striping on most roads are slick when wet.
> Traction arises from the fine grain structure of the grains of sand of
> which it is made and paint does not have that. Most basalt paving
> stones are super slick when wet because they are homogeneous and
> polish to nearly optically smooth surfaces. Fortunately we don't see
> many of these anymore. ("Kopfstein Pflaster" as they were known in
> German speaking areas).

http://www.brugger-steine.at/images/Pflasterer/Kopfsteinpflaster/Kopfsteinpflaster - Seite 1.htm
>
> Shiny black tar fillers of pavement cracks are also slick when wet
> unless they given a sand dusting when made. I have seen bicyclists
> fall on tar stripes when climbing.
>

Aha! Good observation!

 

[* * Chas]

"John Forrest Tomlinson" <[email protected]> wrote in message
news[email protected]...
> On Tue, 7 Nov 2006 21:53:09 -0800, "* * Chas"
> <[email protected]> wrote:
>
> >A lot the currently available tires have a hard
> >narrow center rib and not much pattern on
> >either side for gripping in
> >corners.
>
> What road tires have a center rib? I use mainly racing tires
> (Vittoria, Schwalbe, Michelin, Continental) and haven't see that for
> years.
> --
> JT

Perhaps you are making the assumption that everyone rides "racing
tires".

One of my LBS, Velosport in Berkeley, CA has the widest selection of
tires that I've seen anywhere. They stock at least 50 different kinds of
road tires. At least 1/3 of the road tires that I looked a few months
ago had some degree of center rib that was thicker, harder or less
flexible than the side areas of the treads. I consider that a center
rib.

Many of the pure racing tires that I looked at had thin flexible treads
and no sign of a rib. Panaracer Pasela tires used to have a stiff narrow
center rib that some riders found objectionable. They've changed their
tread pattern on all of their road tires that I've seen except their 27"
x 1 1/8" and 1 1/4" Pasela and Pasela TG tires which still have a narrow
1/4" wide center rib.

I can't name any others at the moment because I was shopping for fast
touring tires. I bought sets of Panaracer Pasela TG in 26 x 1.5, 700c x
25 and 700c x 28. I really like the way they ride so far. I also bought
a set of Conti 700c x 23 GP tires. I like them too but I'm a little
suspicious of how they are going to corner in the wet.

Chas.

 

[* * Chas]

<[email protected]> wrote in message
news:[email protected]...
> Chas who? writes:
>
> >> This morning's regular Tuesday/Thursday-morning ride was memorable
> >> due to some unexpected, and *very* slippery pavement. The fog had
> >> burned off some time earlier, but there was something about what it
> >> left behind in a few places that caused noticeable slipping (a bit
> >> of an uncomfortable feeling as you're going through a corner in a
> >> downhill sprint!).
>
> >> One of the guys decided, at the top of one of the climbs, to let
> >> some air out of his tires. And he was the only person who, in a
> >> corner that didn't look all that bad, went down (hard).
>
> >> Personally, I haven't found much benefit to reducing the air in my
> >> tires when things are wet; wider tires, on the other hand, have
> >> made a noticeable improvement (I run 23c normally, and 25c in the
> >> winter).
>
> >> But what do the traction experts say about reducing air when things
> >> are wet? Does it actually help? And if so, how much do you reduce
> >> the pressure? Is there a point where you have too little air and
> >> the effect is reversed (less traction & control instead of more)?
>
> > Tire tread pattern can make a big difference in corning especially
> > wet versus dry conditions. A lot the currently available tires have
> > a hard narrow center rib and not much pattern on either side for
> > gripping in corners.
>
> Would you care to explain what "tread pattern" does for wet traction
> on pavement? While you're at it, consider that motorcycle and
> aircraft tires are slick and travel as much as ten times as fast in
> downpours as a cornering bicycle.
>
> http://draco.acs.uci.edu/rbfaq/FAQ/8b.13.html
>
> Jobst Brandt

Your citation mentions drag racers and aircraft neither of which make
fast turns. I used to ride motorcycle a lot and I've dumped from hitting
wet spots on the road plus both sand and gravel. High performance
motorcycle tires use soft sticky rubber compounds that provide increased
traction from the weight of the bike and the cornering forces when the
rider is over on the pegs. We're talking about bikes not panes or trains
or whatever.

I personally don't feel comfortable with slick treads on a bike tire.
They're probably great in many situations but I feel more comfortable
with a minor herringbone pattern on the sides of the treads. That's MY
opinion based on many cases of road rash from skidding on wet leaves,
sand, gravel, mud, water, ice, railroad tracks and so on.

Chas.

 

[[email protected]]

Chas who? writes:

>>>> This morning's regular Tuesday/Thursday-morning ride was
>>>> memorable due to some unexpected, and *very* slippery
>>>> pavement. The fog had burned off some time earlier, but there was
>>>> something about what it left behind in a few places that caused
>>>> noticeable slipping (a bit of an uncomfortable feeling as you're
>>>> going through a corner in a downhill sprint!).

>>>> One of the guys decided, at the top of one of the climbs, to let
>>>> some air out of his tires. And he was the only person who, in a
>>>> corner that didn't look all that bad, went down (hard).

>>>> Personally, I haven't found much benefit to reducing the air in
>>>> my tires when things are wet; wider tires, on the other hand,
>>>> have made a noticeable improvement (I run 23c normally, and 25c
>>>> in the winter).

>>>> But what do the traction experts say about reducing air when
>>>> things are wet? Does it actually help? And if so, how much do
>>>> you reduce the pressure? Is there a point where you have too
>>>> little air and the effect is reversed (less traction & control
>>>> instead of more)?

>>> Tire tread pattern can make a big difference in corning especially
>>> wet versus dry conditions. A lot the currently available tires
>>> have a hard narrow center rib and not much pattern on either side
>>> for gripping in corners.

>> Would you care to explain what "tread pattern" does for wet
>> traction on pavement? While you're at it, consider that motorcycle
>> and aircraft tires are slick and travel as much as ten times as
>> fast in downpours as a cornering bicycle.

http://draco.acs.uci.edu/rbfaq/FAQ/8b.13.html

> Your citation mentions drag racers and aircraft neither of which
> make fast turns. I used to ride motorcycle a lot and I've dumped
> from hitting wet spots on the road plus both sand and gravel. High
> performance motorcycle tires use soft sticky rubber compounds that
> provide increased traction from the weight of the bike and the
> cornering forces when the rider is over on the pegs. We're talking
> about bikes not planes or trains or whatever.

We're talking about tire traction on pavement. Hydroplaning is not an
issue, as others have mentioned. Traction on wet pavement is achieved
by rubber contacting the fine structure on the surface of pieces of
aggregate that penetrates the boundary's layer of water and transfers
force. The boundary layer is what remains after bulk water has been
pressed aside. It is that film that is left on a window after a
squeegee has been wiped across it.

This has nothing to do specifically with cornering but of shear-force
between tire and road. If you believe there is no parallel between
bicycles and other rubber tired vehicle, you might explain why. I
mention aircraft because most of us have flown and have noticed the
amazing braking forces achieve at landing speeds on wet runways. This
should give rise to thoughts about traction.

> I personally don't feel comfortable with slick treads on a bike
> tire. They're probably great in many situations but I feel more
> comfortable with a minor herringbone pattern on the sides of the
> treads. That's MY opinion based on many cases of road rash from
> skidding on wet leaves, sand, gravel, mud, water, ice, railroad
> tracks and so on.

Why do you qualify this as "personally". If it is so personal you
should not put it forth as something others should do. You seem to
have tire tread and traction confused when you say you skid on wet
leaves and other lubricants that are unaffected by patterned tread.
Tread patterns have no effect on wet leaves nor on wet manhole covers
for that matter.

How do you explain the general use of slicks on road motorcycles,
especially ones with more than 100HP?

Jobst Brandt

 

[Qui si parla Campagnolo]

* * Chas wrote:
> "John Forrest Tomlinson" <[email protected]> wrote in message
> news[email protected]...
> > On Tue, 7 Nov 2006 21:53:09 -0800, "* * Chas"
> > <[email protected]> wrote:
> >
> > >A lot the currently available tires have a hard
> > >narrow center rib and not much pattern on
> > >either side for gripping in
> > >corners.
> >
> > What road tires have a center rib? I use mainly racing tires
> > (Vittoria, Schwalbe, Michelin, Continental) and haven't see that for
> > years.
> > --
> > JT
>
> Perhaps you are making the assumption that everyone rides "racing
> tires".
>
> One of my LBS, Velosport in Berkeley, CA has the widest selection of
> tires that I've seen anywhere. They stock at least 50 different kinds of
> road tires. At least 1/3 of the road tires that I looked a few months
> ago had some degree of center rib that was thicker, harder or less
> flexible than the side areas of the treads. I consider that a center
> rib.
>
> Many of the pure racing tires that I looked at had thin flexible treads
> and no sign of a rib. Panaracer Pasela tires used to have a stiff narrow
> center rib that some riders found objectionable. They've changed their
> tread pattern on all of their road tires that I've seen except their 27"
> x 1 1/8" and 1 1/4" Pasela and Pasela TG tires which still have a narrow
> 1/4" wide center rib.
>
> I can't name any others at the moment because I was shopping for fast
> touring tires. I bought sets of Panaracer Pasela TG in 26 x 1.5, 700c x
> 25 and 700c x 28. I really like the way they ride so far. I also bought
> a set of Conti 700c x 23 GP tires. I like them too but I'm a little
> suspicious of how they are going to corner in the wet.
>
> Chas.

Always thought a shop that did just bicycle tires and tubes, every tire
and tube, would work well. Small place, inventory intensive, volume
buying and 'discount selling, of course. So if needed that 26 1/38,
590mm beadseat diameter, white wall, they'd have it.

 

[Mike Jacoubowsky]

>> This morning's regular Tuesday/Thursday-morning ride was memorable due to
>> some unexpected, and *very* slippery pavement. The fog had burned off
>> some time earlier, but there was something about what it left behind in a
>> few places that caused noticeable slipping (a bit of an uncomfortable
>> feeling as you're going through a corner in a downhill spint!).
>
> No idea about the original request. Just a word of caution. If you'll ever
> ride in France under wet conditions (rain, fog) avoid all road markings,
> zebra crossing included. They get as slippery as if they were covered in
> soap. The worse are the zebra crossing at the entry/exit from roundabouts,
> where leaning is unavoidable. One moment you are up and the next moment
> you ask yourself who knocked you over.

Road markings are likely the same everywhere; in France, they're no
different than in the US, at least not from my experiences (7 times so far).
Slippery when wet.

Interesting thing I noticed on my last trip to the TdF. On the upper part of
Alpe d'Huez, where someone had very recently painted things on the road in a
corner, they were laying dirt down on top of the "artwork" and then sweeping
it away. The paint was dry so it wasn't embedding in the paint, but could be
that it dulled the surface a bit, giving more traction.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Roberto Divia" <[email protected]> wrote in message
news:[email protected]...
> Mike Jacoubowsky wrote:
>> This morning's regular Tuesday/Thursday-morning ride was memorable due to
>> some unexpected, and *very* slippery pavement. The fog had burned off
>> some time earlier, but there was something about what it left behind in a
>> few places that caused noticeable slipping (a bit of an uncomfortable
>> feeling as you're going through a corner in a downhill spint!).
>
> No idea about the original request. Just a word of caution. If you'll ever
> ride in France under wet conditions (rain, fog) avoid all road markings,
> zebra crossing included. They get as slippery as if they were covered in
> soap. The worse are the zebra crossing at the entry/exit from roundabouts,
> where leaning is unavoidable. One moment you are up and the next moment
> you ask yourself who knocked you over.
>
> Ciao,
> --
> Roberto Divia` Love at first sight is one of the
> greatest
> DepH Bat:53 Mailbox:C02110 labour-saving devices the world has ever
> seen
> Route de Meyrin
> ---------------------------------------------
> Case Postale Phone: +41-22-767-4994
> CH-1211 Geneve 23 CERN Fax: +41-22-767-9585
> Switzerland E-Mail: [email protected]

 

[Johnny Sunset]

jim beam wrote:
> Johnny Sunset wrote:
> > jim beam wrote:
> >> Johnny Sunset wrote:
> >>> * * Chas wrote:
> >>>> ...
> >>>> Tire tread pattern can make a big difference in corning especially wet
> >>>> versus dry conditions. A lot the currently available tires have a hard
> >>>> narrow center rib and not much pattern on either side for gripping in
> >>>> corners.
> >>> Since the rubber in a tire tread is much softer than the pavement
> >>> surface, it will conform to minor irregularities. Patterned tread will
> >>> only decrease the contact area between the tire and pavement.
> >>>
> >>> Bicycle tires are narrow enough and have high enough inflation
> >>> pressures that hydroplaning will not occur under real world conditions,
> >>> so channels in the tread to remove water from between the tire and
> >>> pavement are not needed.
> >>>
> >> it's not inflation pressure that prevents hydroplaning, it's the load on
> >> the tire per its contact area.
> >
> > Which is merely another way of saying what I wrote above, since with
> > flexible bicycle tire casings, contact pressure will depend on
> > inflation pressure.
>
> so if the contact area was 3 square inches not 1 and the inflation
> pressure was still 100lbs, what would the contact pressure be then?
>
> >
> >> bike tires are up near 100psi contact
> >> pressure, enough to disperse water in the contact patch. that pressure
> >> cannot however disperse mud and debris that washes onto roads, in which
> >> case the cogging action of a tread pattern may be of advantage.
> >
> > Does the "herringbone" tread pattern found on many road tires really do
> > anything in this situation?
> >
> [D]o you bother to do your own homework or do you just repeat what others
> tell you?

When I replaced the 35-406 Primo Comet tires with "herringbone" tread
on my bike with smooth tread Avocet [1] 44-406 Fasgrip Freestyle tires,
wet weather braking traction improved significantly.

Setting up a proper tire traction experiment with mud and debris would
be extremely difficult, due to each test run affecting the test surface
and/or the near impossibility of creating identical test surfaces. Even
on smooth surfaces, an instrumented tire traction test is beyond the
means of most individuals. Therefore, the best alternative is to rely
on the consensus of opinion of other's based on their experiences, as
poor as this information may be.

[1] Note Jobst Brandt's association with smooth tread Avocet tires.

--
Tom Sherman - Post Free or Die!

 

[Johnny Sunset]

Peter Chisholm wrote:
> ...
> Always thought a shop that did just bicycle tires and tubes, every tire
> and tube, would work well. Small place, inventory intensive, volume
> buying and 'discount selling, of course. So if needed that 26 1/38,
> 590mm beadseat diameter, white wall, they'd have it.

And if ALL tires and tubes were primarily labeled with the ISO system,
it would make getting the right size tire and/or tube much easier. For
instance, (based on experience) many LBS employees have trouble
differentiating between ISO 406-mm and ISO 451-mm "20-inch" and ISO
305-mm and ISO 349-mm "16-inch" tires and tubes, which can lead to the
owner of a folding upright bicycle or [deleted] getting the wrong size.

--
Tom Sherman - Post Free or Die!

 

[Johnny Sunset]

Jobst Brandt wrote:
> ...
> Shiny black tar fillers of pavement cracks are also slick when wet
> unless they given a sand dusting when made. I have seen bicyclists
> fall on tar stripes when climbing.

I would be very surprised if the material used to fill crack control
joints, fatigue cracks, construction joints, etc. was tar and not
asphalt.

--
Tom Sherman - Post Free or Die!

 

[Werehatrack]

On Wed, 8 Nov 2006 12:12:13 -0800, "* * Chas"
<[email protected]> wrote:

>Your citation mentions drag racers and aircraft neither of which make
>fast turns.

Aircraft make turns that apply high side loads to the tires, and they
must apply substantial braking forces at speeds often in excess of
100mph; the forces involved are well beyond what a bicycle tire must
cope with. And yes, at times they *do* turn at a speed that would
surprise you, particularly when the aircraft lands a bit long or
encounters some loss of traction on the runout due to water, and has
to make a sudden turn onto the assigned taxiway.

>I used to ride motorcycle a lot and I've dumped from hitting
>wet spots on the road plus both sand and gravel. High performance
>motorcycle tires use soft sticky rubber compounds that provide increased
>traction from the weight of the bike and the cornering forces when the
>rider is over on the pegs.

Racing bikes use really soft, sticky compounds, but street bikes in
factory trim use materials that are very similar to those on bicycles;
hard enough to be durable, compliant enough to grip the surface. Real
racing tires have a life expectancy of a few hundred miles at most;
street tires have to go a lot farther...and truly soft, sticky
compounds would not get a DOT rating in any event.

Many years ago, when I was working on motorcycles, nearly all tires
for that market had distinct tread patterns which produced void ratios
of up to 60%; as time passed, however, the real-world experience of an
increasing number of riders was that slicks of a good compound
provided superior traction in all conditions, and the void ratio
dropped until it reached the currently typical point of less than 10%
for performance tires. All along, riding on wet surfaces simply
demanded that the rider treat them as being wet, whether the tires
were smooth or not. The vestigial tread patterns still seen on
motorcycle tires are often present for no other reason than to permit
the inclusion of the tread wear indicators that few bicycle tires
incorporate. A slick can, of course, be made with TWI holes instead
of bars, as is the case with road racing tires, but that's still not
allowed for street-usage tires as far as I know.

>We're talking about bikes not panes or trains
>or whatever.

Trains were not mentioned; why do you include them?

>I personally don't feel comfortable with slick treads on a bike tire.
>They're probably great in many situations but I feel more comfortable
>with a minor herringbone pattern on the sides of the treads. That's MY
>opinion based on many cases of road rash from skidding on wet leaves,
>sand, gravel, mud, water, ice, railroad tracks and so on.

I used to think your position was valid. Then I got a little more
experience, and discovered that Jobst was, indeed, quite correct in
his assertion; tread is seldom, if ever, going to make a difference
for a bike tire on a *clean* wet road surface, and can't improve
traction over a slick tire in dry conditions. In a situation where
there is a lubricated surface, I have observed that a tire with tread
capable of doing some squeegeeing sometimes will seem to slip less
than one that's smooth, but in such conditions the likelihood of that
being enough to keep the bike from dumping is small; if the squeegee
effect is engaging, it's because the tire has already begun to slip,
at which point the slide is already underway and will simply continue.

Tread isn't always a benign thing, either; patterns like those that
were employed on some of the the Slime-branded tires (briefly sold by
Bell, if I recall correctly) actually reduced traction in both wet and
dry conditions by cutting down on the amount of contact face
available; the damn things slide like crazy if you're getting anywhere
close to competitive-level cornering forces, and they *squeak* in
ordinary cornering as the tread nubs squirm on the pavement.


--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Mike Jacoubowsky]

> And if ALL tires and tubes were primarily labeled with the ISO system,
> it would make getting the right size tire and/or tube much easier. For
> instance, (based on experience) many LBS employees have trouble
> differentiating between ISO 406-mm and ISO 451-mm "20-inch" and ISO
> 305-mm and ISO 349-mm "16-inch" tires and tubes, which can lead to the
> owner of a folding upright bicycle or [deleted] getting the wrong size.

Count me as one shop owner that would *love* to have all tires marked
clearly (and asked for) with their ISO numbers.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"Johnny Sunset" <[email protected]> wrote in message
news:[email protected]...
>
> Peter Chisholm wrote:
>> ...
>> Always thought a shop that did just bicycle tires and tubes, every tire
>> and tube, would work well. Small place, inventory intensive, volume
>> buying and 'discount selling, of course. So if needed that 26 1/38,
>> 590mm beadseat diameter, white wall, they'd have it.
>
> And if ALL tires and tubes were primarily labeled with the ISO system,
> it would make getting the right size tire and/or tube much easier. For
> instance, (based on experience) many LBS employees have trouble
> differentiating between ISO 406-mm and ISO 451-mm "20-inch" and ISO
> 305-mm and ISO 349-mm "16-inch" tires and tubes, which can lead to the
> owner of a folding upright bicycle or [deleted] getting the wrong size.
>
> --
> Tom Sherman - Post Free or Die!
>

 

[[email protected]]

Bill Platt writes:

>> Painted and epoxy applique striping on most roads are slick when
>> wet. Traction arises from the fine grain structure of the grains
>> of sand of which it is made and paint does not have that. Most
>> basalt paving stones are super slick when wet because they are
>> homogeneous and polish to nearly optically smooth surfaces.
>> Fortunately we don't see many of these anymore. ("Kopfstein
>> Pflaster" as they were known in German speaking areas).

http://tinyurl.com/yjnff7

>> Shiny black tar fillers of pavement cracks are also slick when wet
>> unless they given a sand dusting when made. I have seen bicyclists
>> fall on tar stripes when climbing.

> Aha! Good observation!

I was thinking more of the larger grey to black basalt stones that
gave the name "Kopfstein" to the stones, being as large as a man's head
and curved so that they were like riding over human skulls:

http://www.bauzentrale.com/news/2006/1frame.htm?0805.php4

Most German city streets and rural roads were paved with them before
WWII. Even parts of the Autobahn had sections of them that were the
ultimate driving challenge in the rain.

Jobst Brandt

 

[Johnny Sunset]

Mike Jacoubowsky wrote:
> > And if ALL tires and tubes were primarily labeled with the ISO system,
> > it would make getting the right size tire and/or tube much easier. For
> > instance, (based on experience) many LBS employees have trouble
> > differentiating between ISO 406-mm and ISO 451-mm "20-inch" and ISO
> > 305-mm and ISO 349-mm "16-inch" tires and tubes, which can lead to the
> > owner of a folding upright bicycle or [deleted] getting the wrong size.
>
> Count me as one shop owner that would *love* to have all tires marked
> clearly (and asked for) with their ISO numbers.

I have asked for tires and tubes by ISO numbers, and received looks of
stunned incomprehension at LBS's.

--
Tom Sherman - Post Free or Die!

 

[Roberto Divia]

Mike Jacoubowsky wrote:
>>> This morning's regular Tuesday/Thursday-morning ride was memorable due to
>>> some unexpected, and *very* slippery pavement. The fog had burned off
>>> some time earlier, but there was something about what it left behind in a
>>> few places that caused noticeable slipping (a bit of an uncomfortable
>>> feeling as you're going through a corner in a downhill spint!).
>> No idea about the original request. Just a word of caution. If you'll ever
>> ride in France under wet conditions (rain, fog) avoid all road markings,
>> zebra crossing included. They get as slippery as if they were covered in
>> soap. The worse are the zebra crossing at the entry/exit from roundabouts,
>> where leaning is unavoidable. One moment you are up and the next moment
>> you ask yourself who knocked you over.
>
> Road markings are likely the same everywhere; in France, they're no
> different than in the US, at least not from my experiences (7 times so far).
> Slippery when wet.

My experience covers France, Germany, Austria, Switzerland, Hungary, Sweden
and Italy. U.S. is not on my logbook :-(.

In France all markings are slippery (they all use the same paint) and they
are very, very slippery. Just thinking "Hey, I'm riding on a road marking"
makes you fall. Not joking.

In the other countries I have visited, markings do not use always the same
paint/pattern (they vary with the place and with the type) and are not so
slippery.

Ciao,
--
Roberto Divia` Love at first sight is one of the greatest
DepH Bat:53 Mailbox:C02110 labour-saving devices the world has ever seen
Route de Meyrin 385 ---------------------------------------------
Case Postale Phone: +41-22-767-4994
CH-1211 Geneve 23 CERN Fax: +41-22-767-9585
Switzerland E-Mail: [email protected]

 

[sergio]

Mike Jacoubowsky wrote:
> Road markings are likely the same everywhere; in France, they're no
> different than in the US, at least not from my experiences (7 times so far).
> Slippery when wet.

Let me vouch for Italy.
They are mostly not slippery at all; sprayed so lightly, with cheap
stuff, that they fade away in a few months. Not the same everywhere,
though.

Sergio
Pisa

 

[Mark Hickey]

"Mike Jacoubowsky" <[email protected]> wrote:

>> And if ALL tires and tubes were primarily labeled with the ISO system,
>> it would make getting the right size tire and/or tube much easier. For
>> instance, (based on experience) many LBS employees have trouble
>> differentiating between ISO 406-mm and ISO 451-mm "20-inch" and ISO
>> 305-mm and ISO 349-mm "16-inch" tires and tubes, which can lead to the
>> owner of a folding upright bicycle or [deleted] getting the wrong size.
>
>Count me as one shop owner that would *love* to have all tires marked
>clearly (and asked for) with their ISO numbers.

Me too (though I'm not exactly a "shop" owner).

Of course, to do this, the bicycle industry would have to invent
another new standard to replace any confusion that had been
eliminated.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

 

[Jay Beattie]

<[email protected]> wrote in message
news:[email protected]...
> Roberto Divia writes:
>
> >> This morning's regular Tuesday/Thursday-morning ride was
memorable
> >> due to some unexpected, and *very* slippery pavement. The
fog had
> >> burned off some time earlier, but there was something about
what it
> >> left behind in a few places that caused noticeable slipping
(a bit
> >> of an uncomfortable feeling as you're going through a corner
in a
> >> downhill sprint!).
>
> > No idea about the original request. Just a word of caution.
If
> > you'll ever ride in France under wet conditions (rain, fog)
avoid
> > all road markings, zebra crossing included. They get as
slippery as
> > if they were covered in soap. The worse are the zebra
crossing at
> > the entry/exit from roundabouts, where leaning is
unavoidable. One
> > moment you are up and the next moment you ask yourself who
knocked
> > you over.
>
> Painted and epoxy applique striping on most roads are slick
when wet.
> Traction arises from the fine grain structure of the grains of
sand of
> which it is made and paint does not have that. Most basalt
paving
> stones are super slick when wet because they are homogeneous
and
> polish to nearly optically smooth surfaces. Fortunately we
don't see
> many of these anymore. ("Kopfstein Pflaster" as they were
known in
> German speaking areas).
>
> Shiny black tar fillers of pavement cracks are also slick when
wet
> unless they given a sand dusting when made. I have seen
bicyclists
> fall on tar stripes when climbing.

Especially the filler they use on Mt. Hamilton -- or maybe in
California. I used to do that climb every few weeks when I lived
in SJ, and I didn't recall that filler being so slippery. The
last time I did the climb while visiting a few years ago, I found
the filler on the SCV side was incredibly slippery -- far
slipperier than any filler I find here in Oregon.

As for tread pattern, what about the effect of a pattern on
less-than-clean road? I am riding slicks over wet, fallen
leaves, and it is worse than riding over painted stripes. I was
thinking that someting with a little bite would give me better
traction this time of year with all the blow down (something
short of ATB tread, obviously). -- Jay Beattie.

 

[[email protected]]

Jay Beattie writes:

>>>> This morning's regular Tuesday/Thursday-morning ride was
>>>> memorable due to some unexpected, and *very* slippery pavement.
>>>> The fog had burned off some time earlier, but there was something
>>>> about what it left behind in a few places that caused noticeable
>>>> slipping (a bit of an uncomfortable feeling as you're going
>>>> through a corner in a downhill sprint!).

>>> No idea about the original request. Just a word of caution. If
>>> you'll ever ride in France under wet conditions (rain, fog) avoid
>>> all road markings, zebra crossing included. They get as slippery
>>> as if they were covered in soap. The worse are the zebra crossing
>>> at the entry/exit from roundabouts, where leaning is unavoidable.
>>> One moment you are up and the next moment you ask yourself who
>>> knocked you over.

>> Painted and epoxy applique striping on most roads are slick when
>> wet. Traction arises from the fine grain structure of the grains
>> of sand of which it is made and paint does not have that. Most
>> basalt paving stones are super slick when wet because they are
>> homogeneous and polish to nearly optically smooth surfaces.
>> Fortunately we don't see many of these anymore. ("Kopfstein
>> Pflaster" as they were known in German speaking areas).

>> Shiny black tar fillers of pavement cracks are also slick when wet
>> unless they given a sand dusting when made. I have seen bicyclists
>> fall on tar stripes when climbing.

> Especially the filler they use on Mt. Hamilton -- or maybe in
> California. I used to do that climb every few weeks when I lived in
> SJ, and I didn't recall that filler being so slippery. The last
> time I did the climb while visiting a few years ago, I found the
> filler on the SCV side was incredibly slippery -- far slipperier
> than any filler I find here in Oregon.

> As for tread pattern, what about the effect of a pattern on
> less-than-clean road? I am riding slicks over wet, fallen leaves,
> and it is worse than riding over painted stripes. I was thinking
> that something with a little bite would give me better traction this
> time of year with all the blow down (something short of ATB tread,
> obviously).

As you said, you are riding ON wet leaves and it's the leaves that are
sliding so the tread has no effect on traction with the road.

Interestingly, car and truck tire treads are still in the dark about
what tread patterns can do. Trucks have tread patterns that make
howling noises and have no effect on performance other than causing
more heat from tread squirm (flexing that bulges rubber into voids).
I don't believe there have been any hydroplaning events with trucks.

Passenger cars, in contrast, have tread patterns that play to the same
fears bicyclists express about hydroplaning and have all sorts of
curved V-shaped patterns that do nothing useful. Right now it seems
not much is getting from research (Formula one racing) past racing and
motorcycles tires.

Jobst Brandt

 

[[email protected]]

On 09 Nov 2006 17:38:20 GMT, [email protected] wrote:

[snip]

>I don't believe there have been any hydroplaning events with trucks.

[snip]

Dear Jobst,

Assuming that you mean semi-trailer trucks, google for trucks,
hydroplaning, and horne, a fellow whose studies disagree with you:

http://www.google.com/search?hl=en&lr=&as_qdr=all&q=hydroplaning+trucks+horne

"Predicting the Minimum Dynamic Hydroplaning Speed for Aircraft, Bus,
Truck, and Automobiles Tires Rolling on Flooded Pavements"

Cheers,

Carl Fogel