Grip - sticky 23 vs average 25?

"Pete Biggs" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Will a 23mm tyre with a particularly soft/grippy compound grip the road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than make up
for the difference in compound?

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro Race
2 (not that I'm sure the Pro Grip really is especially grippy, but
assuming it is...).

Thanks.

~PB

It should primarily depend on the coefficient of friction (Greek letter mu)
of the materials in contact.

These are the simple physics equations:

breaking distance = v^2 / (2 mu g) (I think) doesn't account for the
effects of drag...

curve slideout speed = sqrt(r g mu)

No mass involved (assuming your break pads can supply enough force to get
near the maximum static friction force of road-tire). More mass allows for a
proportionally greater max friction force, but it also proportionally
increases the force of deceleration. Same with a turn:
m g mu = m (v^2 / r) which simplifies to the equation above.

The equations are deceptively simple because mu is just an empirically
determined constant.
Contact patch of the two tires you mentioned will be determined by the
inflation pressure (not tire size unless the design places different limits
on max psi). Perhaps contact patch might have some small effects on mu due
to the differing deformations of the rubber that tire designers would
consider especially on car tires. But greater contact patch doesn't give
what some might consider an intuitive increase in frictional force --
there's more area but less normal force per unit area (unless it's because
your ass got bigger in which case the equations above show you're not any
better off).

Jobst has indicated that slick tires with carbon black can have mu>1
allowing an angle of 45 to 48 degrees.
http://www-math.science.unitn.it/Bike/Countries/Europe/Tour_Reports/Tour_of_the_Alps_Gallery/tiretest.jpg
And says that his tests showed that any substantial tread lowers mu (due to
tread squirm), even in the rain for bike tires where hydroplaning isn't an
issue.

--Art

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than make up
for the difference in compound?

It would depend on the surface wouldn't it. In truth I don't know the answer but
I do know it will depend on what traction limiting factors exist.

Quoted message said:

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro Race
2 (not that I'm sure the Pro Grip really is especially grippy, but
assuming it is...).

What I'm particularly wondering is where and how you ride that ultimate traction
on dry pavement is a factor?

Ron

RonSonic said:

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the
road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than
make up
for the difference in compound?

It would depend on the surface wouldn't it. In truth I don't know the
answer but I do know it will depend on what traction limiting factors
exist.

Quoted message said:

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro
Race 2 (not that I'm sure the Pro Grip really is especially grippy,
but
assuming it is...).

What I'm particularly wondering is where and how you ride that
ultimate traction on dry pavement is a factor?

I had a front-wheel slip last November on what looked like clean dry
pavement that broke my hip. I was turning into a side-road, doing well
under 20 mph, not leaning like crazy. It was too warm for ice but there
may have been some oil or deisal on the road (I don't know) but I am now
paranoid about grip in all conditions, so I want to increase it, even if
it's unlikely that I will need it. I don't want to ever fall again.

I specifically mentioned dry conditions because I'm always extremely
cautious in the wet anyway. You never know, my confidence in the dry
might eventually increase to the point of leaning at silly angles :-)

So back to the question: My understanding was that traction of wider
tyres was greater, partly/mainly because air pressure is lower (perhaps
allowing the tyre to stay in contact with the pavement more of the time
instead of bouncing?), but is that not enough of a factor to beat an
especially soft compound?

I certainly don't mind if we broaden the subject out to include slightly
greasy or dusty roads -- that's the greatest danger for me personally --
roads that basically look ok but where an unexpected or invisible small
patch of [censored] can catch you out.

~PB

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than make up
for the difference in compound?

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro Race
2 (not that I'm sure the Pro Grip really is especially grippy, but
assuming it is...).

IME compound wins out over anything else in determining how well a bike
tyre grips. I've currently got some fat 1.6" tyres on my 26" wheeled
touring bike which are downright dangerous in the wet, for instance. I
used to have 1.3" tyres which gripped like a limpet in virtually all
conditions (wet leaves being the notable exception, where no tyre works
well because the leaves slide over one another).

The flipside - if it has a grippy compound, it may be badly worn after
only 1,000 miles on the rear wheel. You don't get nowt for owt, as they
say in Yorkshire.

Zog The Undeniable said:

IME compound wins out over anything else in determining how well a
bike tyre grips. I've currently got some fat 1.6" tyres on my 26"
wheeled touring bike which are downright dangerous in the wet, for
instance. I used to have 1.3" tyres which gripped like a limpet in
virtually all conditions (wet leaves being the notable exception,
where no tyre works well because the leaves slide over one another).

Thanks, Mr Zog.

Quoted message said:

The flipside - if it has a grippy compound, it may be badly worn after
only 1,000 miles on the rear wheel. You don't get nowt for owt, as
they say in Yorkshire.

I could use a hardier rear tyre.

~PB

Pete Biggs said:

Thanks, Mr Zog.

Ah...I'd never though that someone would assume my online pseudonym was
based on Mr Zog's Sex Wax (The Best For Your Stick).

In reality, "Zog The Undeniable" was a name I once saw scratched on the
wooden surround of a pool table. The e-mail address works, but the
psuedonym is protection against current/future employers running a
search on my name and finding postings where I just might have mentioned
them ;-) Not a concern for retired folk or the self-employed, of course.

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the
road better (in the dry) than a 25mm tyre with an average compound
(for a modern race tyre), assuming the tyres are otherwise similar
and are inflated appropriately?

Quoted message said:

In other words, will the extra width and lower pressure more than
make up for the difference in compound?

Quoted message said:

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro
Race 2 (not that I'm sure the Pro Grip really is especially grippy,
but assuming it is...).

I think you better assess more accurately how "grippy" your tread is
before attributing that ability to these tires. I suspect there is no
difference among better tires other than tread patterns and tire
width. You can try this by using a front wheel placed in contact with
pavement and see at what angle to the surface it slips out as you push
on it holding on to the top of the wheel pushing with your hands.
This isn't high precision, but if your tires have higher traction than
others you should be able to see the difference even with such light
loads.

If they aren't slicks then heavier loads make a difference, loads that
would deform the ridges and grooves.

Jobst Brandt
[email hidden]

"Pete Biggs" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

RonSonic said:

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the
road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than
make up
for the difference in compound?

It would depend on the surface wouldn't it. In truth I don't know the
answer but I do know it will depend on what traction limiting factors
exist.

Quoted message said:

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro
Race 2 (not that I'm sure the Pro Grip really is especially grippy,
but
assuming it is...).

What I'm particularly wondering is where and how you ride that
ultimate traction on dry pavement is a factor?

I had a front-wheel slip last November on what looked like clean dry
pavement that broke my hip. I was turning into a side-road, doing well
under 20 mph, not leaning like crazy. It was too warm for ice but there
may have been some oil or deisal on the road (I don't know) but I am now
paranoid about grip in all conditions, so I want to increase it, even if
it's unlikely that I will need it. I don't want to ever fall again.

I specifically mentioned dry conditions because I'm always extremely
cautious in the wet anyway. You never know, my confidence in the dry
might eventually increase to the point of leaning at silly angles :-)

So back to the question: My understanding was that traction of wider
tyres was greater, partly/mainly because air pressure is lower (perhaps
allowing the tyre to stay in contact with the pavement more of the time
instead of bouncing?), but is that not enough of a factor to beat an
especially soft compound?

Did you even read my response?

It's the compound that matters on a road. That paragraph is full of inane
statements. "Bounces"?

If you made a right-angled right (or possibly left if your spelling of
"tyre" is any indication) turn starting to the outside of a full lane moving
to the inside and finishing wide again, using the equation,

v= sqrt(r g mu)

gives a crash speed of around 25mph good conditions, and very roughly: 19mph
wet, probably a lot less for oil, sand maybe 15 mph and <=8mph for ice. You
might simply have hit a round rock squarely that started a slide that was
unrecoverable at the reduced kinetic friction, though you would have had to
have taken a tighter curve than the one I described at the speed you stated
for that to have been unrecoverable on clean pavement.

Buy the tire with the best compound. (Though as W. said it's probably
irrelevant with junk conditions). Now equating that with the marketing term
"Pro Grip" is another matter altogether.

--Art
(I'm neither a physicist nor an engineer so it's possible I have made some
errors in which case I'm sure I'll get clobbered. If not someone back me
up.)

Quoted message said:

I certainly don't mind if we broaden the subject out to include slightly
greasy or dusty roads -- that's the greatest danger for me personally --
roads that basically look ok but where an unexpected or invisible small
patch of [censored] can catch you out.

~PB

<[email hidden]> a écrit dans le message de :
news:[email hidden]...

Quoted message said:

I think you better assess more accurately how "grippy" your tread is
before attributing that ability to these tires. I suspect there is no
difference among better tires other than tread patterns and tire
width.

Well, had you done some _recent_ reading, you would have found hard research
and testing on just this. Try Le Cycle, February 2005, where the slip
results for 50 different tested tires ranged from 41.1 to 52.7 degrees from
horizontal.

Quoted message said:

You can try this by using a front wheel placed in contact with
pavement and see at what angle to the surface it slips out as you push
on it holding on to the top of the wheel pushing with your hands.

I think that if one can guess from casual observation that a frame with a 72
degree seat tube is slacker than one with a 74 degree slant, one also could
see the kind of difference you don't.

Quoted message said:

This isn't high precision, but if your tires have higher traction than
others you should be able to see the difference even with such light
loads.

I haven't any credentials as an engineer, but just reading real world test
results lets me get a good idea of what precision testing will get you.
Again, I recommend reading an article or two should you find the time.

Quoted message said:

If they aren't slicks then heavier loads make a difference, loads that
would deform the ridges and grooves.

Without offering any guess on my part, the test results in the same article,
on "rain" tires shows that there is a healthy difference between rain and
dry conditions for these tested models.

Just helping out with your reading list about tires, which may have
stagnated a little.
--
Bonne route,

Sandy
Verneuil-sur-Seine FR

Pete Biggs said:

So back to the question: My understanding was that traction of wider
tyres was greater, partly/mainly because air pressure is lower
(perhaps allowing the tyre to stay in contact with the pavement more
of the time instead of bouncing?),

I think this is the major difference between various tires. However, if decent
quality tires of any width are being used, I don't think most riders could run
close enough to the limit with enough consistency for differences in tire
performance to matter. Whatever it is that would take you down on one tire
would likely do the same with another.

Quoted message said:

but is that not enough of a factor
to beat an especially soft compound?

Only a testing maching would tell, but those are controlled circumstances. On a
real road I don't think it's the deciding factor. Rider skill and judgement is.

Matt O.

Pete Biggs said:

RonSonic said:

Pete Biggs said:

Will a 23mm tyre with a particularly soft/grippy compound grip the
road
better (in the dry) than a 25mm tyre with an average compound (for a
modern race tyre), assuming the tyres are otherwise similar and are
inflated appropriately?

In other words, will the extra width and lower pressure more than
make up
for the difference in compound?

It would depend on the surface wouldn't it. In truth I don't know the
answer but I do know it will depend on what traction limiting factors
exist.

Quoted message said:

I'm particularly wondering about Michelin Pro Grip 23 v Michelin Pro
Race 2 (not that I'm sure the Pro Grip really is especially grippy,
but
assuming it is...).

What I'm particularly wondering is where and how you ride that
ultimate traction on dry pavement is a factor?

I had a front-wheel slip last November on what looked like clean dry
pavement that broke my hip. I was turning into a side-road, doing well
under 20 mph, not leaning like crazy. It was too warm for ice but there
may have been some oil or deisal on the road (I don't know) but I am now
paranoid about grip in all conditions, so I want to increase it, even if
it's unlikely that I will need it. I don't want to ever fall again.

Ouch. Damn right that'd leave me a bit skittish myself.

Quoted message said:

I specifically mentioned dry conditions because I'm always extremely
cautious in the wet anyway. You never know, my confidence in the dry
might eventually increase to the point of leaning at silly angles :-)

So back to the question: My understanding was that traction of wider
tyres was greater, partly/mainly because air pressure is lower (perhaps
allowing the tyre to stay in contact with the pavement more of the time
instead of bouncing?), but is that not enough of a factor to beat an
especially soft compound?

I certainly don't mind if we broaden the subject out to include slightly
greasy or dusty roads -- that's the greatest danger for me personally --
roads that basically look ok but where an unexpected or invisible small
patch of [censored] can catch you out.

Here's what I can say with some certainty, I don't think the grippiness of the
rubber compound is as important as negotiating small hazards. I say that because
we know from experience the kind of accident you had simply doesn't happen with
a truly clean, dry, even road or there'd be cyclists scattered in all the
gutters. The wider, lower pressure tire will be better at negotiating the odd
bit of [censored] in the road. On a dry, clean road tread on the tire makes no
positive difference in traction. I know from experience that some tread is
helpful with patches of stuff on the road. Here in Florida there are little
streaks of sand blown across a lot of less used roads and those can be
treacherous. I've got cyclocross tires on at the moment and they are way more
secure on stuff like that. Ironically they are a lot squirrellier in hard
cornering.

Anyway, I'd go up a size and run a lightly treaded tire if I were worried about
being ambushed by that thing that lives under the pavement tripping pedestrians
and messing up cyclists.

Ron

Art M said:

Did you even read my response?

Yes I did and I appreciate it (and this one), thanks, but I didn't know it
was the reponse to end all responses! I'm trying to provoke responses
from others as well. The more responses I get, the better I'll feel about
drawing a conclusion from them. I kind of arguing because my belief has
always been that wider tyres grip better but I *am* prepared to change my
mind.

Quoted message said:

It's the compound that matters on a road. That paragraph is full of
inane statements. "Bounces"?

By "bounce" I mean the more it's inflated, the more likely the tyre is to
loose contact with the ground as it hits a bump, possibly initiating a
slide when it comes back down. Just one of the many factors I'm trying to
consider.

"An overinflated tire can bounce on surface roughnesses. This can
cause dangerous interruptions in traction, particularly if it happens
during cornering."
"A correctly inflated tire will absorb surface irregularities without
bouncing and losing traction."
-- Sheldon Brown, www.sheldonbrown.com/tires.html#pressure

If I want to use lower pressure then I should really use a wider tyre (to
avoid pinch flats and low RR) but I'm finding it hard to find wider tyres
with particularly soft compounds, hence my dilema. But /maybe/ I will
indeed stop worrying about the Bounce Factor and go with whatever I think
will be the grippiest compound.

~PB

Sandy le Urre said:

Quoted message said:

I think you better assess more accurately how "grippy" your tread
is before attributing that ability to these tires. I suspect there
is no difference among better tires other than tread patterns and
tire width.

Quoted message said:

Well, had you done some _recent_ reading, you would have found hard
research and testing on just this. Try Le Cycle, February 2005,
where the slip results for 50 different tested tires ranged from
41.1 to 52.7 degrees from horizontal.

How about a URL reference so that we can all take advantage of these
reports. Google comes up with a lot of "Le cycle de l'eau" and the
like. I'm curious how these values were measured and which tires did
what. On the other hand, why do you keep this information secret when
it seems to be germane to this thread?

Jobst Brandt
[email hidden]

Pete Biggs said:

If I want to use lower pressure then I should really use a wider tyre
(to avoid pinch flats and low RR) but I'm finding it hard to find
wider tyres with particularly soft compounds, hence my dilema. But
/maybe/ I will indeed stop worrying about the Bounce Factor and go
with whatever I think will be the grippiest compound.

Sizes are only nominal anyway. I've been riding on some Vittorias (Open Corsa
CX TT) which are rated at 23mm but as big as most 25mm. They're probably the
best tires I've ever used -- incredibly fast, great handling, able to run at low
or high pressures, and very damage resistant. It was only when they got
paper-thin that the flats started coming. Until then they seemed impervious to
anything. I've since replaced them with some Vredestein Fortezzas -- the same
23mm size but actually much skinnier, and not nearly supple. Got 'em much
quicker at less than half the cost, though.

Matt O.

<[email hidden]> a écrit dans le message de :
news:[email hidden]...

Quoted message said:

Sandy le Urre said:

Quoted message said:

I think you better assess more accurately how "grippy" your tread
is before attributing that ability to these tires. I suspect there
is no difference among better tires other than tread patterns and
tire width.

Quoted message said:

Well, had you done some _recent_ reading, you would have found hard
research and testing on just this. Try Le Cycle, February 2005,
where the slip results for 50 different tested tires ranged from
41.1 to 52.7 degrees from horizontal.

How about a URL reference so that we can all take advantage of these
reports. Google comes up with a lot of "Le cycle de l'eau" and the
like. I'm curious how these values were measured and which tires did
what. On the other hand, why do you keep this information secret when
it seems to be germane to this thread?

Jobst Brandt
[email hidden]

Sorry - this is print medium. A magazine. Actual paper and ink stuff.
Kind of retro. Published in France, read throughout the world. At finer
kiosks (almost) everywhere.

I kept nothing secret - this is a well circulated magazine, at least here,
in France. And it is last month's edition. I don't republish copyright
materials. You shouldn't either. That's stealing.
--
Bonne route,

Sandy
Verneuil-sur-Seine FR

Sandy said:

<[email hidden]> a écrit dans le message de :
news:[email hidden]...

Quoted message said:

Sandy le Urre writes:

Quoted message said:

Quoted message said:

Quoted message said:

Well, had you done some _recent_ reading, you would have found hard
research and testing on just this. Try Le Cycle, February 2005,
where the slip results for 50 different tested tires ranged from
41.1 to 52.7 degrees from horizontal.

How about a URL reference so that we can all take advantage of these
reports. Google comes up with a lot of "Le cycle de l'eau" and the
like. I'm curious how these values were measured and which tires did
what. On the other hand, why do you keep this information secret when
it seems to be germane to this thread?

Quoted message said:

Sorry - this is print medium. A magazine. Actual paper and ink stuff.
Kind of retro. Published in France, read throughout the world. At
finer kiosks (almost) everywhere.

Total monthly sales appear to be about 37000 of which only about 3600
copies are outside of France. Hardly enough to be available almost
everywhere.

Quoted message said:

I kept nothing secret - this is a well circulated magazine, at least
here, in France. And it is last month's edition. I don't republish
copyright materials. You shouldn't either. That's stealing.

Brief excerpts are generally ruled to come under the fair use
provisions. The original poster asked his question with reference to
two specific tires, so it would certainly be helpful to mention if those
were included and how they performed.

"Peter" <[email hidden]> a écrit dans le message de :
news:[email hidden]...

Quoted message said:

Total monthly sales appear to be about 37000 of which only about 3600
copies are outside of France. Hardly enough to be available almost
everywhere.

Looks like you could find something about it, right ? However, for an
authority on a subject so narrow as bicycle tires and their grip
characteristics, one would think that keeping up with current literature
would be a habit. Anyway, I did offer the reference, the magazine is
readily available, and I might even be persuaded to send a copy to our
learned friend.

Quoted message said:

Quoted message said:

I kept nothing secret - this is a well circulated magazine, at least
here, in France. And it is last month's edition. I don't republish
copyright materials. You shouldn't either. That's stealing.

Brief excerpts are generally ruled to come under the fair use provisions.
The original poster asked his question with reference to two specific
tires, so it would certainly be helpful to mention if those were included
and how they performed.

Well, that may be a very fair statement. I did give, you may have noted,
the overall range reported. As another attempt at satisfying the OP's
inquiry, the answers are:

Pro Grip 42.5° dry - 44° wet
Pro 2 Race 48.2° dry (not tested wet)
Pro 2 Light 48.2° dry (not tested wet)
--
Bonne route,

Sandy
Verneuil-sur-Seine FR

Sandy le Urre said:

Quoted message said:

Quoted message said:

> I think you better assess more accurately how "grippy" your tread
> is before attributing that ability to these tires. I suspect
> there is no difference among better tires other than tread
> patterns and tire width.

Quoted message said:

Quoted message said:

Quoted message said:

Well, had you done some _recent_ reading, you would have found
hard research and testing on just this. Try Le Cycle, February
2005, where the slip results for 50 different tested tires ranged
from 41.1 to 52.7 degrees from horizontal.

Quoted message said:

Quoted message said:

How about a URL reference so that we can all take advantage of
these reports. Google comes up with a lot of "Le cycle de l'eau"
and the like. I'm curious how these values were measured and which
tires did what. On the other hand, why do you keep this
information secret when it seems to be germane to this thread?

Quoted message said:

Sorry - this is print medium. A magazine. Actual paper and ink
stuff. Kind of retro. Published in France, read throughout the
world. At finer kiosks (almost) everywhere.

Quoted message said:

I kept nothing secret - this is a well circulated magazine, at least
here, in France. And it is last month's edition. I don't republish
copyright materials. You shouldn't either. That's stealing.

I think you are hiding behind copyright laws. It is permissible to
cite various parts of articles and pieces from books if you aren't
making commercial use from that. Besides, you could describe what you
read in your own words. How about letting others in on what you
discovered?

Jobst Brandt
[email hidden]

Sandy said:

Pro Grip 42.5° dry - 44° wet
Pro 2 Race 48.2° dry (not tested wet)
Pro 2 Light 48.2° dry (not tested wet)

Thanks v much! Do they have numbers for Vittoria Open Corsa?

~PB