Differential front and rear tyres [Archive]

carlfogel@comcast.net

01-03-1970, 08:04 PM

On Nov 19, 3:51 am, Artoi <ar...@hotmail.com> wrote:
> I am wondering what people think of running different tyres front and
> back on a road bike? Recently the rear of my pair of Vittoria Open Corsa
> Evo Cx has worn thin and suffered a number of flats yet the front one is
> still in pretty good shape. So I am wondering what if I paired the
> Vittoria with a more puncture and wear resistant Conti GP4000 at the
> rear? Note here that the Vittoria is considered to be a race tyre that
> wears pretty quickly.
>
> So the logic is as follows.
>
> Given that,
> 1) Rear tyre's wear rate is greater.
> 2) Front tyre is more important for bike control.
> 3) High TPI tyres gives a "better" ride.
>
> Then a more durable tyre for the rear with a better riding tyre at the
> front would balance the performance benefits of each and would retire at
> a similar time.
>
> Any comments?

Dear Artoi,

What's the advantage of having the tires "retire at the same time"?

If there isn't any advantage to synchronized tire replacement, then
you're back to trying to decide whether you want a tire that lasts
longer or rolls easier, presumably based on some tests of tires in a
magazine--and those tires may have changed by the time you decide to
buy one and ride it for months.

Frankly, handling doesn't seem likely to be something that the rider
can actually feel during ordinary riding, at least not between two
700c tires of roughly the same width, tread pattern, and inflation.

After all, no one routinely rides so close to the limit that a
different tire of the same width and inflation would cause a crash.
(If anyone did, he'd be crashing all the time, since the difference
between the tires is likely to be rather smaller than the variation in
speed and road surface.)

As for rolling resistance differences, it's unlikely that any rider
can "feel" the kind of speed difference between one 700c tire and
another of the same width, even if he compares the best tire to the
worst tire.

This test measured the RR for 18 700c tires:

http://ddata.over-blog.com/xxxyyy/0/02/72/10/clincher-specs.html

You can compare the effect of RR on this calculator:

http://austinimage.com/bp/velocityN/velocity.html

300 watt
kmh speed
RR kmh increase
#01 best tire 0.0038 37.7106 1.3
#06 6th best 0.0048 37.2669 0.9
#13 6th worst 0.0058 36.8238 0.5
#18 worst tire 0.0069 36.3373 0.0

It's unlikely that a rider can actually feel the 0.85 mph difference
between the best tire's 23.43 mph and the worst tire's 22.58 mph while
he's putting out 300 watts--he needs a digital speedometer to measure
that kind of difference.

Cheers,

Carl Fogel

Morten Reippuert Knudsen

01-03-1970, 08:04 PM

Artoi <artoi@hotmail.com> wrote:
> I am wondering what people think of running different tyres front and
> back on a road bike? Recently the rear of my pair of Vittoria Open Corsa
> Evo Cx has worn thin and suffered a number of flats yet the front one is
> still in pretty good shape. So I am wondering what if I paired the
> Vittoria with a more puncture and wear resistant Conti GP4000 at the
> rear? Note here that the Vittoria is considered to be a race tyre that
> wears pretty quickly.
>
> So the logic is as follows.
>
> Given that,
> 1) Rear tyre's wear rate is greater.
> 2) Front tyre is more important for bike control.
> 3) High TPI tyres gives a "better" ride.

more road contact area an more flexible sidewalls will provide you
with a more grip.

Notice that vittoria counts the threads doubble, witch means that 290
is equal to 145 compared to michelins with 127 threads.

my choice for the front is a 25mm Michelin Pro2race, the grip and
smoothness is similar to Vittorias now discontinued 23mm Open Extreeme
witch i have always found to be a nicer tyre than the CX's.

The Michelin is also very puncture resistent when riding on dry roads and
lasts at least twice the km count of the vittorias. I haved tried the
conti 4000, but i never liked the 3000's so im sticking with the michelins.

If you want a durable rear tire i can recocment Michelins Krylion
carbon. For the rear the isn't mutch difference between 23 and 25mm.
For the front 25mm has a better grip, and better comfort - especialy
the pro2race.
as of roling resistance the 25mm pro2race actually has lower
resistance than the 23mm version. The weight is almost the same. Among
other top level tires 25mm are noticeable heavier than 23mm.

--
Morten Reippuert Knudsen :-) <http://blog.reippuert.dk>

Merlin Works CR-3/2.5 & Campagnolo Chorus 2007.

Tom Sherman

01-03-1970, 08:05 PM

Art Harris wrote:
> ...
> Yes, rear tires definitely wear much faster for a number of reasons.
> And front tires either rot or get cut before they wear out.

My front tires wear out first.

> So, when the rear tire wears out, move the front tire to the rear, and
> install a new tire on the front. This insures that the newer tire is
> on front.

butbutbut, my rear wheel is bigger than the front! How do I stretch the
tire onto the rim? ;)

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Artoi

01-03-1970, 08:05 PM

In article <4741a794$0$14098$742ec2ed@news.sonic.net>,
jobst.brandt@stanfordalumni.org wrote:

> Artoi who? writes:
>
> > I am wondering what people think of running different tyres front
> > and back on a road bike? Recently the rear of my pair of Vittoria
> > Open Corsa Evo Cx has worn thin and suffered a number of flats yet
> > the front one is still in pretty good shape. So I am wondering what
> > if I paired the Vittoria with a more puncture and wear resistant
> > Conti GP4000 at the rear? Note here that the Vittoria is considered
> > to be a race tyre that wears pretty quickly.
>
> > So the logic is as follows.
>
> > Given that,
> > 1) Rear tyre's wear rate is greater.
> > 2) Front tyre is more important for bike control.
> > 3) High TPI tyres gives a "better" ride.
>
> > Then a more durable tyre for the rear with a better riding tyre at
> > the front would balance the performance benefits of each and would
> > retire at a similar time.
>
> > Any comments?
>
> http://www.sheldonbrown.com/brandt/rear-flats.html
>
> Jobst Brandt

Yes, that should have been the 4th point. Tendency for rear punctures,
thereby needing a tougher tyre at the rear.
--

Mike Jacoubowsky

01-03-1970, 08:05 PM

> i have tried having a thinner tire on the back to reduce friction on
> the back and it works. have a 23c in the front and a 20c on the back.
> you should pick 0.5 mph on your average ride. con's you might get more
> flats!

I'm skeptical that changing from a 23 to a 20c tire in the rear would be
responsible for anything close to a .5mph difference. Even the professionals
run wider tires than that, and if they could get a speed boost using a
narrower tire, they'd do it.

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

<cyclingthings@gmail.com> wrote in message
news:912f0eca-5d68-45a3-a4fd-53275709654b@b36g2000hsa.googlegroups.com...
> On Nov 19, 5:51 am, Artoi <ar...@hotmail.com> wrote:
>> I am wondering what people think of running different tyres front and
>> back on a road bike? Recently the rear of my pair of Vittoria Open Corsa
>> Evo Cx has worn thin and suffered a number of flats yet the front one is
>> still in pretty good shape. So I am wondering what if I paired the
>> Vittoria with a more puncture and wear resistant Conti GP4000 at the
>> rear? Note here that the Vittoria is considered to be a race tyre that
>> wears pretty quickly.
>>
>> So the logic is as follows.
>>
>> Given that,
>> 1) Rear tyre's wear rate is greater.
>> 2) Front tyre is more important for bike control.
>> 3) High TPI tyres gives a "better" ride.
>>
>> Then a more durable tyre for the rear with a better riding tyre at the
>> front would balance the performance benefits of each and would retire at
>> a similar time.
>>
>> Any comments?
>> --
>
> pro and semi pro riders do it all the time. they will have diferent
> tires and wheels.
> i have tried having a thinner tire on the back to reduce friction on
> the back and it works. have a 23c in the front and a 20c on the back.
> you should pick 0.5 mph on your average ride. con's you might get more
> flats!
> carlos
> www.bikingthings.com
> ride fast, get fit, live better, be happy

Artoi

01-03-1970, 08:05 PM

In article
<912f0eca-5d68-45a3-a4fd-53275709654b@b36g2000hsa.googlegroups.com>,
cyclingthings@gmail.com wrote:

> pro and semi pro riders do it all the time. they will have diferent
> tires and wheels.
> i have tried having a thinner tire on the back to reduce friction on
> the back and it works. have a 23c in the front and a 20c on the back.
> you should pick 0.5 mph on your average ride. con's you might get more
> flats!

Interesting idea. Have to keep that as an option.

But I have read elsewhere that the 20mm actually has greater rolling
resistance than the 23mm. While the 20mm has lower air resistance. So
shouldn't the setup be the reverse?
--

Rik O'Shea

01-03-1970, 08:05 PM

On 19 Nov, 15:31, cyclingthi...@gmail.com wrote:

> > --
>
> pro and semi pro riders do it all the time. they will have diferent
> tires and wheels.
> i have tried having a thinner tire on the back to reduce friction on
> the back and it works. have a 23c in the front and a 20c on the back.
> you should pick 0.5 mph on your average ride. con's you might get more
> flats!
> carloswww.bikingthings.com
> ride fast, get fit, live better, be happy

The general accepted wisdom is the opposite i.e. wider tire at the
rear and narrower one at the front. The rationale being that for the
same type of tire the wider one will generally have a lower rolling
resistance (plus the fact that most of your weight is on the rear) and
the front tire's higher rolling resistance is offset by improved
aerodynamics (in that the aerodynamics of the front wheel are more
important than the rear since it penetrates the air first and a
narrower tire is more aligned with the rim than a wider one). However
all of the above is difficult to prove (in that the improvement can
fall within the realm of statistical standard error) so if you "feel"
faster with your setup then stick with it.

Artoi

01-03-1970, 08:05 PM

In article <4741bc56$1@news.nb.nu>,
Lou Holtman <lholremovethis@planet.nl> wrote:

> Artoi wrote:
> > I am wondering what people think of running different tyres front and
> > back on a road bike?
>
> Why do you/people think that front and rear should be the same?
>
> > Recently the rear of my pair of Vittoria Open Corsa
> > Evo Cx has worn thin and suffered a number of flats yet the front one is
> > still in pretty good shape. So I am wondering what if I paired the
> > Vittoria with a more puncture and wear resistant Conti GP4000 at the
> > rear? Note here that the Vittoria is considered to be a race tyre that
> > wears pretty quickly.
> >
> > So the logic is as follows.
> >
> > Given that,
> > 1) Rear tyre's wear rate is greater.
> > 2) Front tyre is more important for bike control.
> > 3) High TPI tyres gives a "better" ride.
>
>
> >
> > Then a more durable tyre for the rear with a better riding tyre at the
> > front would balance the performance benefits of each and would retire at
> > a similar time.
> >
> > Any comments?
> > --
>
> You have seen the light...hallelujah ;-) or put the new one in front
> and move the front tyre to the back.

Actually that's what I used to do, so no news to me.

My specific question here is somewhat different, one where one
deliberately select and pair a more wear resistant tyre for the rear and
a higher TPI tyre with poorer wear for the front, aiming to equalize the
usage time for the pair.
--

carlfogel@comcast.net

01-03-1970, 08:05 PM

On Mon, 19 Nov 2007 09:01:03 -0800, "Mike Jacoubowsky"
<mikej1@ix.netcom.com> wrote:

>> i have tried having a thinner tire on the back to reduce friction on
>> the back and it works. have a 23c in the front and a 20c on the back.
>> you should pick 0.5 mph on your average ride. con's you might get more
>> flats!
>
>I'm skeptical that changing from a 23 to a 20c tire in the rear would be
>responsible for anything close to a .5mph difference. Even the professionals
>run wider tires than that, and if they could get a speed boost using a
>narrower tire, they'd do it.
>
>--Mike-- Chain Reaction Bicycles
>www.ChainReactionBicycles.com

Dear Mike,

Your skepticism is well-founded.

Plug 200 watts into both sides of this calculator:

http://austinimage.com/bp/velocityN/velocity.html

You have to reduce the rolling resistance on _both_ tires from the
default 0.0050 to 0.0034 to gain 0.8 kmh, a 33% drop in rolling
resistance.

That means that the scheme to replace a 23c with a 20c tire on just
the rear would somehow have to reduce the rear tire's rolling
resistance about 66% by narrowing only 15%.

If you started with a 23c tire that had 0.0050 RR, you'd need to find
a magical 20c version that had only 0.0016 RR.

The best tires in this link were the clinchers on the lower right
chart and achieved only 0.0038:

http://www.rouesartisanales.com/article-1503651.html

http://ddata.over-blog.com/xxxyyy/0/02/72/10/clincher-specs.html

http://ddata.over-blog.com/xxxyyy/0/02/72/10/tubular-specs.html

The best clincher tire was 24.0 mm wide with a 0.0038 RR.

The best 21.5 mm clincher tire had a worse RR of 0.0048.

The narrower tubular tires followed the same pattern, with all thinner
tires having worse RR than the best wider tires.

Cheers,

Carl Fogel

Lou Holtman

01-03-1970, 08:07 PM

Artoi wrote:
> In article <4741bc56$1@news.nb.nu>,
> Lou Holtman <lholremovethis@planet.nl> wrote:
>
>> Artoi wrote:
>>> I am wondering what people think of running different tyres front and
>>> back on a road bike?
>> Why do you/people think that front and rear should be the same?
>>
>>> Recently the rear of my pair of Vittoria Open Corsa
>>> Evo Cx has worn thin and suffered a number of flats yet the front one is
>>> still in pretty good shape. So I am wondering what if I paired the
>>> Vittoria with a more puncture and wear resistant Conti GP4000 at the
>>> rear? Note here that the Vittoria is considered to be a race tyre that
>>> wears pretty quickly.
>>>
>>> So the logic is as follows.
>>>
>>> Given that,
>>> 1) Rear tyre's wear rate is greater.
>>> 2) Front tyre is more important for bike control.
>>> 3) High TPI tyres gives a "better" ride.
>>
>>> Then a more durable tyre for the rear with a better riding tyre at the
>>> front would balance the performance benefits of each and would retire at
>>> a similar time.
>>>
>>> Any comments?
>>> --
>> You have seen the light...hallelujah ;-) or put the new one in front
>> and move the front tyre to the back.
>
> Actually that's what I used to do, so no news to me.
>
> My specific question here is somewhat different, one where one
> deliberately select and pair a more wear resistant tyre for the rear and
> a higher TPI tyre with poorer wear for the front, aiming to equalize the
> usage time for the pair.
> --

Why bother to equalize the wear for the front and the rear tire. Wear
out the rear and replace it. Wear out the front and replace it. I don't
even bother to put the new one in front. Puncture resistance and
comfort are much more important for me to choose a different tire for
the rear. Therefor I put a wider tire in the back. They last longer too,
but that is a bonus.

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

jobst.brandt@stanfordalumni.org

01-03-1970, 08:07 PM

Artoi who? writes:

>>> I am wondering what people think of running different tyres front
>>> and back on a road bike? Recently the rear of my pair of Vittoria
>>> Open Corsa Evo Cx has worn thin and suffered a number of flats yet
>>> the front one is still in pretty good shape. So I am wondering what
>>> if I paired the Vittoria with a more puncture and wear resistant
>>> Conti GP4000 at the rear? Note here that the Vittoria is considered
>>> to be a race tyre that wears pretty quickly.

>>> So the logic is as follows.

>>> Given that,
>>> 1) Rear tyre's wear rate is greater.
>>> 2) Front tyre is more important for bike control.
>>> 3) High TPI tyres gives a "better" ride.

>>> Then a more durable tyre for the rear with a better riding tyre at
>>> the front would balance the performance benefits of each and would
>>> retire at a similar time.

>>> Any comments?

http://www.sheldonbrown.com/brandt/rear-flats.html

> Yes, that should have been the 4th point. Tendency for rear
> punctures, thereby needing a tougher tyre at the rear.

If there were such a tire, and there isn't, Carl Fogel would have long
ago switched to them instead of patching tubes. The tire you seek you
don't want because it doesn't roll worth a damn. Besides, my front
tires (the same as the ones on the rear) wear out nearly as fast as
rear tires from braking and cornering. In any case, when switched to
the rear they wear out in a few hundred miles.

Jobst Brandt

bfd

01-03-1970, 08:07 PM

On Nov 19, 5:40 pm, jobst.bra...@stanfordalumni.org wrote:
> Artoi who? writes:
> >>> I am wondering what people think of running different tyres front
> >>> and back on a road bike? Recently the rear of my pair of Vittoria
> >>> Open Corsa Evo Cx has worn thin and suffered a number of flats yet
> >>> the front one is still in pretty good shape. So I am wondering what
> >>> if I paired the Vittoria with a more puncture and wear resistant
> >>> Conti GP4000 at the rear? Note here that the Vittoria is considered
> >>> to be a race tyre that wears pretty quickly.
> >>> So the logic is as follows.
> >>> Given that,
> >>> 1) Rear tyre's wear rate is greater.
> >>> 2) Front tyre is more important for bike control.
> >>> 3) High TPI tyres gives a "better" ride.
> >>> Then a more durable tyre for the rear with a better riding tyre at
> >>> the front would balance the performance benefits of each and would
> >>> retire at a similar time.
> >>> Any comments?
>
> http://www.sheldonbrown.com/brandt/rear-flats.html
>
> > Yes, that should have been the 4th point. Tendency for rear
> > punctures, thereby needing a tougher tyre at the rear.
>
> If there were such a tire, and there isn't, Carl Fogel would have long
> ago switched to them instead of patching tubes. The tire you seek you
> don't want because it doesn't roll worth a damn. Besides, my front
> tires (the same as the ones on the rear) wear out nearly as fast as
> rear tires from braking and cornering. In any case, when switched to
> the rear they wear out in a few hundred miles.
>
Actually, if you believe the marketing, there are a set of tires that
address the OP's "needs:"

http://tinyurl.com/64cvo

"On the rear wheel, GP Force guarantees superior power transmission.
23mm wide, consisting of an ultra fine nylon fabric and protected from
punctures by a double breaker belt under the tread, it embodies the
strength of Continental racing tires.

The GP Force is constructed for high mileage performance. Traction and
cornering behaviour remainS stable for thousands of racing kilometres.

GP Force 3 plies/ 330 tpi + Nylon Double Breaker"

I mean come on, who is going to doubt Contiental?.....

datakoll

01-03-1970, 08:07 PM

On Nov 19, 8:40 pm, jobst.bra...@stanfordalumni.org wrote:
> Artoi who? writes:
> >>> I am wondering what people think of running different tyres front
> >>> and back on a road bike? Recently the rear of my pair of Vittoria
> >>> Open Corsa Evo Cx has worn thin and suffered a number of flats yet
> >>> the front one is still in pretty good shape. So I am wondering what
> >>> if I paired the Vittoria with a more puncture and wear resistant
> >>> Conti GP4000 at the rear? Note here that the Vittoria is considered
> >>> to be a race tyre that wears pretty quickly.
> >>> So the logic is as follows.
> >>> Given that,
> >>> 1) Rear tyre's wear rate is greater.
> >>> 2) Front tyre is more important for bike control.
> >>> 3) High TPI tyres gives a "better" ride.
> >>> Then a more durable tyre for the rear with a better riding tyre at
> >>> the front would balance the performance benefits of each and would
> >>> retire at a similar time.
> >>> Any comments?
>
> http://www.sheldonbrown.com/brandt/rear-flats.html
>
> > Yes, that should have been the 4th point. Tendency for rear
> > punctures, thereby needing a tougher tyre at the rear.
>
> If there were such a tire, and there isn't, Carl Fogel would have long
> ago switched to them instead of patching tubes. The tire you seek you
> don't want because it doesn't roll worth a damn. Besides, my front
> tires (the same as the ones on the rear) wear out nearly as fast as
> rear tires from braking and cornering. In any case, when switched to
> the rear they wear out in a few hundred miles.
>
> Jobst Brandt- Hide quoted text -
>
> - Show quoted text -

JB is just too old to roll. So much for charachter assassination.
During HD Touring, a wider rear tire (you were waiting for this,
right?) propelled with greater force cornering not for speed but for
balance gives more control for stability and direction than the
thinner tire. 356 SC ? stock or E prod ?
In fact, porposing to the obvious fallacy, thinning 5-8mm more will
soon give slipperyness and squirm,
or as addding too much weight on the standard tire gives slipperness
and squirm at the rear.
Off course, what JB states is also correct.
Fat tire front? right ! confronted with slippery surfaces, avoiding
front washout is A Pus. But! balance the rear width with weight
considerations.
A tractor tread setup may be in odor. Circumferential ribs front with
greater tread surface and a digger rib rear for propulsion.
On the shoes: chinese Italian loafers cost the same as 1963 Italian-
North African loafers.

Ron Ruff

01-03-1970, 08:08 PM

On Nov 19, 7:44 pm, carlfo...@comcast.net wrote:
> What's the advantage of having the tires "retire at the same time"?

I'm with you Carl... 'cause I'm lazy. I've been running a Michelin Pro
2 on the front and a Krylion on the back and replace each when
necessary. I still get a lot more mileage out of the front.

Barry

01-03-1970, 08:08 PM

> It's unlikely that a rider can actually feel the 0.85 mph difference
> between the best tire's 23.43 mph and the worst tire's 22.58 mph while
> he's putting out 300 watts--he needs a digital speedometer to measure
> that kind of difference.

That difference is actually larger than I would have expected. I agree that a
rider probably can't feel the difference in speed, but if pushing hard on a
fast group ride, it might make the difference between keeping up and getting
dropped.

Artoi

01-03-1970, 08:08 PM

In article
<adf683ab-628c-49e6-837f-3d27837f43dc@i29g2000prf.googlegroups.com>,
carlfogel@comcast.net wrote:

> What's the advantage of having the tires "retire at the same time"?

Good question Carl. I guess it's just another way to skin a cat.

But seriously though. Given the combination of Vittoria Open Corsa Evo
Cx and Conti GP4000 (two tyres that just happened to be in my
possession), I figured that the Vittoria can stay at the front for its
improved handling (290tpi) but poorer wear. While the GP4000 provides
better wear and puncture resistance. Doesn't that make sense given the
importance of front wheel in handling and the higher wear and puncture
rate of the rear? And if the wear rate ratio stays at 1:2, both will
probably retire at the same time.
--

carlfogel@comcast.net

01-03-1970, 08:08 PM

On Mon, 19 Nov 2007 20:41:38 -0800 (PST), Ron Ruff
<rruffrruff@yahoo.com> wrote:

>On Nov 19, 7:44 pm, carlfo...@comcast.net wrote:
>> What's the advantage of having the tires "retire at the same time"?
>
>I'm with you Carl... 'cause I'm lazy. I've been running a Michelin Pro
>2 on the front and a Krylion on the back and replace each when
>necessary. I still get a lot more mileage out of the front.

Dear Ron,

With highwheelers, the teacup was turned upside down, but the tempest
was much the same.

On highwheelers, the little rear wheel had to rotate far more times
than the big front wheel.

Bearings were primitive.

So ads in "Bicycle Annual" for 1879 boasted if the hind wheel, as they
called it, had super-duper bearings:

http://i9.tinypic.com/8fe6138.jpg

It's from an unnumbered page near the end of this google book, so a
direct link is well-nigh impossible:

http://books.google.com/books?id=wYg3AAAAMAAJ&pg=PA198&lpg=PA198&dq=%22keen's+eclipse%22&source=web&ots=BszxqQAjVP&sig=aooIqM3qS9tg5SJl1pY__x9jzDQ#PPT24,M1

I haven't figured out what the difference is between the detachable
foot and toe rests that clamp onto the highwheeler fork.

Cheers,

Carl Fogel

carlfogel@comcast.net

01-03-1970, 08:09 PM

On Tue, 20 Nov 2007 08:28:00 -0500, "Barry" <a@b.c> wrote:

>> It's unlikely that a rider can actually feel the 0.85 mph difference
>> between the best tire's 23.43 mph and the worst tire's 22.58 mph while
>> he's putting out 300 watts--he needs a digital speedometer to measure
>> that kind of difference.
>
>That difference is actually larger than I would have expected. I agree that a
>rider probably can't feel the difference in speed, but if pushing hard on a
>fast group ride, it might make the difference between keeping up and getting
>dropped.

Dear Barry,

The speed difference could be even larger if worse tires were
tested--imagine rolling along on a pair of knobby MTB tires.

Of course, the question in this thread was about replacing only one
tire, not both, so the speed improvement would be only about half as
much.

On a fast group ride, it probably wouldn't make much difference at
all, for the same reason that 90% of the field in the Tour de France
finishes together on ordinary days--drafting is the overwhelming
factor in group rides on the flats.

In a time trial or a climbing day, where drafting is eliminated, the
difference in RR between various 700c tires can make a difference to
racers, but it's still a small difference.

Where it would make a huge difference is if a rider is just barely
able to keep up by drafting a group of much better riders. If his
tires held him back just a little bit more and he couldn't draft, the
peloton would leave him dramatically behind--but the tires would be
exposing the fact that he really needs to find a slower group, where
he can take a turn at the front. (Recreational groups, of course, will
often welcome riders who struggle to keep up because the better riders
like the social side of things, hope to help the slower riders
improve, or enjoy gloating over--er, never mind.

Cheers,

Carl Fogel

Artoi

01-03-1970, 08:09 PM

In article <Gaednd5GovwEfN_anZ2dnUVZ_vWtnZ2d@comcast.com>,
"Barry" <a@b.c> wrote:

> > It's unlikely that a rider can actually feel the 0.85 mph difference
> > between the best tire's 23.43 mph and the worst tire's 22.58 mph while
> > he's putting out 300 watts--he needs a digital speedometer to measure
> > that kind of difference.
>
> That difference is actually larger than I would have expected. I agree that
> a
> rider probably can't feel the difference in speed, but if pushing hard on a
> fast group ride, it might make the difference between keeping up and getting
> dropped.

May not be able to feel it, but that kind of speed difference can be
significant in a race.
--

Artoi

01-03-1970, 08:10 PM

In article <47431c22$1@news.nb.nu>,
Lou Holtman <lholremovethis@planet.nl> wrote:

> Why bother to equalize the wear for the front and the rear tire. Wear
> out the rear and replace it. Wear out the front and replace it. I don't
> even bother to put the new one in front. Puncture resistance and
> comfort are much more important for me to choose a different tire for
> the rear. Therefor I put a wider tire in the back. They last longer too,
> but that is a bonus.

Equalizing the wear was just an incidental possibility for the
particular pairing I am looking at.

The reason for wanting a better riding tyre at the front was because the
bike will be used for some racing. So I figured it might make some sense
to keep the tyre with the higher tpi at the front.

If I was just commuting, then I wouldn't have considered from this angle.
--

Barry

01-03-1970, 08:11 PM

> Where it would make a huge difference is if a rider is just barely
> able to keep up by drafting a group of much better riders. If his
> tires held him back just a little bit more and he couldn't draft, the
> peloton would leave him dramatically behind--but the tires would be
> exposing the fact that he really needs to find a slower group, where
> he can take a turn at the front.

This is exactly the situation I had in mind. I'm one of the weaker riders in
my usual group, and if I'm having a bad day and the fast guys really push it,
I'll struggle to keep up. I almost never drop, but an extra 0.8 mph might
save me on the tough days, and allow me to pull longer on the average days.
There don't seem to be enough riders around here to make an A- group, so
unless I want to take it easy, I have to suck it up and ride with the big boys
(and girls).

carlfogel@comcast.net

01-03-1970, 08:11 PM

On Tue, 20 Nov 2007 13:55:36 -0500, "Barry" <a@b.c> wrote:

>> Where it would make a huge difference is if a rider is just barely
>> able to keep up by drafting a group of much better riders. If his
>> tires held him back just a little bit more and he couldn't draft, the
>> peloton would leave him dramatically behind--but the tires would be
>> exposing the fact that he really needs to find a slower group, where
>> he can take a turn at the front.
>
>This is exactly the situation I had in mind. I'm one of the weaker riders in
>my usual group, and if I'm having a bad day and the fast guys really push it,
>I'll struggle to keep up. I almost never drop, but an extra 0.8 mph might
>save me on the tough days, and allow me to pull longer on the average days.
>There don't seem to be enough riders around here to make an A- group, so
>unless I want to take it easy, I have to suck it up and ride with the big boys
>(and girls).

Dear Barry,

Sorry that there aren't more riders nearby. Console yourself that
you're paying attention and getting more out of the ride, not goofing
off like the leaders. Poor devils, it must be boring for them to know
that they can always keep up, right?

Concentrating on your position to reduce wind drag is not only free,
but more likely to produce 0.8 mph improvements than tire selection.

If you're still tempted to spend a lot of money on new tires, remember
that the 0.8 mph theoretical difference was only for replacing the
very worst tires with the very best out of 18 tires.

A more likely difference for average tire improvement is about 0.4
mph--and that assumes that the tire that you buy is still as good as
the tire that was measured in a test months or years ago. Tire
companies have a bad habit of "improving" things.

As an aside, racers often mounted old tires for the most events and
stages in the Tour de France. hoping that the RR would be lower with
the rubber tread worn thinner.

Normal riders rarely notice that kind of minute improvement. Instead,
we tend to talk about how our new (and thicker) tires roll really
smooth and fast compared to those old (and thinner) tires that must
have been slowing us down.

This year, I find it more convenient to blame my slower speed on
contrary headwinds during a bad winter than my new tires.

Cheers,

Carl Fogel

carlfogel@comcast.net

01-03-1970, 08:11 PM

Artoi

01-03-1970, 08:11 PM

In article
<f1319625-5cad-431d-bfb6-98e6cd59fbfc@i37g2000hsd.googlegroups.com>,
bfd <bfd853@yahoo.com> wrote:

> Actually, if you believe the marketing, there are a set of tires that
> address the OP's "needs:"
>
> http://tinyurl.com/64cvo
>
> "On the rear wheel, GP Force guarantees superior power transmission.
> 23mm wide, consisting of an ultra fine nylon fabric and protected from
> punctures by a double breaker belt under the tread, it embodies the
> strength of Continental racing tires.
>
> The GP Force is constructed for high mileage performance. Traction and
> cornering behaviour remainS stable for thousands of racing kilometres.
>
> GP Force 3 plies/ 330 tpi + Nylon Double Breaker"
>
> I mean come on, who is going to doubt Contiental?.....

Good one! :)

I think I'll be happy with GP4000 for its puncture resistance at the
moment.
--

Rik O'Shea

01-03-1970, 08:12 PM

>
> As an aside, racers often mounted old tires for the most events and
> stages in the Tour de France. hoping that the RR would be lower with
> the rubber tread worn thinner.
>
> Carl Fogel

As an interesting aside when Tony Rominger won the Giro in 1995 every
single rider on this team (that's 9 riders) had both tires changed
every second day. The tires where tubular (dont ask me about the
logistics of this!) and apparently no one on the team suffered a
puncture during the event.

21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
help the mechanics)

bfd

01-03-1970, 08:14 PM

On Nov 21, 2:16 am, "Rik O'Shea" <rikos...@yahoo.com> wrote:
> > As an aside, racers often mounted old tires for the most events and
> > stages in the Tour de France. hoping that the RR would be lower with
> > the rubber tread worn thinner.
>
> > Carl Fogel
>
> As an interesting aside when Tony Rominger won the Giro in 1995 every
> single rider on this team (that's 9 riders) had both tires changed
> every second day. The tires where tubular (dont ask me about the
> logistics of this!) and apparently no one on the team suffered a
> puncture during the event.
>
> 21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
> help the mechanics)

That's alot of tires, its good to be sponsored! Also, I recall
watching the "Lance Chronicles," or whatever it was called that
Discovery (or was it US Postal) had an old-school mechanic guy who
*aged* their tubular tires in a cellar. He had a ton of them stored by
age. I believe some were as old as 10 years!

Obviously it must have worked as I never recalled Lance or any of his
key players ever getting a flat on a major stage!

carlfogel@comcast.net

01-03-1970, 08:14 PM

On Wed, 21 Nov 2007 02:16:50 -0800 (PST), "Rik O'Shea"
<rikoshea@yahoo.com> wrote:

>
>>
>> As an aside, racers often mounted old tires for the most events and
>> stages in the Tour de France. hoping that the RR would be lower with
>> the rubber tread worn thinner.
>>
>> Carl Fogel
>
>As an interesting aside when Tony Rominger won the Giro in 1995 every
>single rider on this team (that's 9 riders) had both tires changed
>every second day. The tires were tubular (dont ask me about the
>logistics of this!) and apparently no one on the team suffered a
>puncture during the event.
>
>21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
>help the mechanics)
>

Dear Rik,

Teams often replace costly equipment because of strange logic.

With tires, it's hard to see what the point of 2-day replacement is.

The amount of wear in two days of long distance bicycle racing is
typically trivial for tires. These aren't race-car tires that show
impressive wear in a few laps--the reduction in tread thickness on a
road bicycle in 300 miles would be hard to measure with a micrometer.

With slightly worn tread, the tires would be infinitesimally more
likely to flat, but they'd also roll a tiny bit faster and
theoretically corner a smidgen better, so it's not even clear whether
new tires are theoretically better or worse than slightly worn tires.

In any case, I'd be surprised if there was any actual data showing a
measurable practical change in any quality for 2-day old tires versus
3-day old tires. If there is a real advantage, then presumably a daily
change would be even better.

That's the trouble with most arguments about extremely tiny
theoretical improvements. Riders and mechanics have only so much time
and money, so fiddling with increasingly trivial minutiae means less
time and money for the dull but important matters.

An alternate theory is that 2-day replacement guarantees that
everything has been checked--no damaged tire, no tire with a slow
leak, no tubular with a hidden glue problem will be in use long enough
to cause a problem.

Again, daily replacement would provide an even more thorough check.

Most excessive replacement schedules look like wishful thinking.
People replace large, visible, and dramatic items in a hopeful rather
than sensible fashion. Even when there's nothing to be done, we still
like the illusion that we can do something--and often do it.

I wonder if that Giro team replaced their brake pads every two days?
The brake pads would wear more than the tires, but both would probably
work just fine on the third day.

Why not replace the cables every two days?

I suspect that mechanics like to replace tires that often because they
can do it easily. In the weeks before the race, they can occupy
themselves building up large stocks of spares and looking busy. During
the race, they can swap the new wheelsets in quickly, giving
themselves and the riders the dramatic illusion that a lot of
important work has been done.

Replacing brake pads and shift cables would be much more work on a
daily basis and much less likely to give that psychological boost. We
can "feel" a distinct improvement when we see a brand-new tire, but
it's harder to notice the difference between a 2-day old and a brand
new shift cable.

Cheers,

Carl Fogel

Tom Sherman

01-03-1970, 08:14 PM

Rik O'Shea wrote:
>> As an aside, racers often mounted old tires for the most events and
>> stages in the Tour de France. hoping that the RR would be lower with
>> the rubber tread worn thinner.
>>
>> Carl Fogel
>
> As an interesting aside when Tony Rominger won the Giro in 1995 every
> single rider on this team (that's 9 riders) had both tires changed
> every second day. The tires where tubular (dont ask me about the
> logistics of this!) and apparently no one on the team suffered a
> puncture during the event.
>
> 21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
> help the mechanics)

With that much glue to sniff, the mechanics were likely feeling really good.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

carlfogel@comcast.net

01-03-1970, 08:14 PM

On Wed, 21 Nov 2007 11:42:50 GMT, Artoi <artoi@hotmail.com> wrote:

>In article
><adf683ab-628c-49e6-837f-3d27837f43dc@i29g2000prf.googlegroups.com>,
> carlfogel@comcast.net wrote:
>
>> What's the advantage of having the tires "retire at the same time"?
>
>Good question Carl. I guess it's just another way to skin a cat.

[snip]

Dear Artoi,

Er, what cat is being skinned?

Cheers,

Carl Fogel

Lou Holtman

01-03-1970, 08:15 PM

Artoi wrote:
> In article <47431c22$1@news.nb.nu>,
> Lou Holtman <lholremovethis@planet.nl> wrote:
>
>> Why bother to equalize the wear for the front and the rear tire. Wear
>> out the rear and replace it. Wear out the front and replace it. I don't
>> even bother to put the new one in front. Puncture resistance and
>> comfort are much more important for me to choose a different tire for
>> the rear. Therefor I put a wider tire in the back. They last longer too,
>> but that is a bonus.
>
> Equalizing the wear was just an incidental possibility for the
> particular pairing I am looking at.
>
> The reason for wanting a better riding tyre at the front was because the
> bike will be used for some racing. So I figured it might make some sense
> to keep the tyre with the higher tpi at the front.
>
> If I was just commuting, then I wouldn't have considered from this angle.
> --

Do you think Vittoria Open Corsa Evo handles better than a GP4000S? I
doubt that.

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

datakoll

01-03-1970, 08:15 PM

On -

fatter tire more grip? punch the snow video and look for oil

http://www.christini.com/media.php?s=videos

M-gineering

01-03-1970, 08:15 PM

Lou Holtman wrote:

> Do you think Vittoria Open Corsa Evo handles better than a GP4000S? I
> doubt that.

yes, they are slightly wider ;)

--
/Marten

info(apestaartje)m-gineering(punt)nl

jobst.brandt@stanfordalumni.org

01-03-1970, 08:15 PM

Lou Holtman writes:

>>> Why bother to equalize the wear for the front and the rear
>>> tire. Wear out the rear and replace it. Wear out the front and
>>> replace it. I don't even bother to put the new one in front.
>>> Puncture resistance and comfort are much more important for me to
>>> choose a different tire for the rear. Therefor I put a wider tire
>>> in the back. They last longer too, but that is a bonus.

>> Equalizing the wear was just an incidental possibility for the
>> particular pairing I am looking at.

>> The reason for wanting a better riding tyre at the front was
>> because the bike will be used for some racing. So I figured it
>> might make some sense to keep the tyre with the higher tpi at the
>> front.

>> If I was just commuting, then I wouldn't have considered from this
>> angle.

> Do you think Vittoria Open Corsa Evo handles better than a GP4000S?
> I doubt that.

What do you mean by "handles"? How does one determine whether one
tire handles better than another? I don't see riders cornering at the
limit of traction on mountain roads in this area.

It is usually in junior racing that riders find their limits by
crashing (without breaking bones) and with most new riders today not
being youngsters, they rarely test handling limits of tires. That
appears to be borne out by the many colored tires that have poor wet
traction that no one seems to notice. Handling appears irrelevant.

Jobst Brandt

Artoi

01-03-1970, 08:15 PM

In article <4744610e$1@news.nb.nu>,
Lou Holtman <lholremovethis@planet.nl> wrote:

> Do you think Vittoria Open Corsa Evo handles better than a GP4000S? I
> doubt that.

It's supposed to theoretically and many riders vouch for that. More
scientific data? I don't have any.
--

russellseaton1@yahoo.com

01-03-1970, 08:15 PM

On Nov 21, 10:46 am, Lou Holtman <lholremovet...@planet.nl> wrote:
> Artoi wrote:
> > In article <47431c2...@news.nb.nu>,
> > Lou Holtman <lholremovet...@planet.nl> wrote:
>
> >> Why bother to equalize the wear for the front and the rear tire. Wear
> >> out the rear and replace it. Wear out the front and replace it. I don't
> >> even bother to put the new one in front. Puncture resistance and
> >> comfort are much more important for me to choose a different tire for
> >> the rear. Therefor I put a wider tire in the back. They last longer too,
> >> but that is a bonus.
>
> > Equalizing the wear was just an incidental possibility for the
> > particular pairing I am looking at.
>
> > The reason for wanting a better riding tyre at the front was because the
> > bike will be used for some racing. So I figured it might make some sense
> > to keep the tyre with the higher tpi at the front.
>
> > If I was just commuting, then I wouldn't have considered from this angle.
> > --
>
> Do you think Vittoria Open Corsa Evo handles better than a GP4000S? I
> doubt that.

I've used the Vittoria Open Corsa Evo CX 700x25 on front and rear and
the Continental GP4000 700x23 on the front. On PBP the Vittoria tires
flatted 4 times on the rear and 3 times on the front. On rides before
PBP I flatted a few times with the Continental and eventually cut up
the sidewall so the tire had to be botted and replaced in a hurry.
Can't give much of an opinion on ride quality and such of these
tires. But the Vittoria flat more often. But the Continental aren't
very good either. The Vittoria are easy to mount though.

>
> Lou
> --
> Posted by news://news.nb.nu (http://www.nb.nu)- Hide quoted text -
>
> - Show quoted text -

jobst.brandt@stanfordalumni.org

01-03-1970, 08:16 PM

someone writes:

>>> As an aside, racers often mounted old tires for the most events
>>> and stages in the Tour de France. hoping that the RR would be
>>> lower with the rubber tread worn thinner.

Grasping at straws!

>> As an interesting aside when Tony Rominger won the Giro in 1995
>> every single rider on this team (that's 9 riders) had both tires
>> changed every second day. The tires where tubular (don't ask me
>> about the logistics of this!) and apparently no one on the team
>> suffered a puncture during the event.

Well that's proof if I ever saw it. New tires don't puncture!

>> 21 days/2 * 9 riders * 2 tires = 180 tires used during the event
>> (God help the mechanics)

> That's alot of tires, its good to be sponsored! Also, I recall
> watching the "Lance Chronicles," or whatever it was called that
> Discovery (or was it US Postal) had an old-school mechanic guy who
> *aged* their tubular tires in a cellar. He had a ton of them stored
> by age. I believe some were as old as 10 years!

The tire aging story has a life of its own and won't die. Just the
same we have long threads on clinchers dying of age as the casings
frazzle and tread cracks. In the days of tubulars the same thing
occurred but no one wanted to talk about it. Blasphemy!

> Obviously it must have worked as I never recalled Lance or any of his
> key players ever getting a flat on a major stage!

Well that's proof if I ever saw it. Old tires don't puncture!

Jobst Brandt

datakoll

01-03-1970, 08:16 PM

well, using the well known heavy load squirm and squish as baseline
you own a bike shop or a gas well assemble the tires and rims trying
to computerize the so-called subjective data and work your way down
thru combinations
for the given course: surface type, weather...
till you squish and squirm then back off to the last batch rims/tires
and start using the stopwatch.

bfd

01-03-1970, 08:16 PM

On Nov 21, 10:49 am, jobst.bra...@stanfordalumni.org wrote:
> Lou Holtman writes:
> >>> Why bother to equalize the wear for the front and the rear
> >>> tire. Wear out the rear and replace it. Wear out the front and
> >>> replace it. I don't even bother to put the new one in front.
> >>> Puncture resistance and comfort are much more important for me to
> >>> choose a different tire for the rear. Therefor I put a wider tire
> >>> in the back. They last longer too, but that is a bonus.
> >> Equalizing the wear was just an incidental possibility for the
> >> particular pairing I am looking at.
> >> The reason for wanting a better riding tyre at the front was
> >> because the bike will be used for some racing. So I figured it
> >> might make some sense to keep the tyre with the higher tpi at the
> >> front.
> >> If I was just commuting, then I wouldn't have considered from this
> >> angle.
> > Do you think Vittoria Open Corsa Evo handles better than a GP4000S?
> > I doubt that.
>
> What do you mean by "handles"? How does one determine whether one
> tire handles better than another? I don't see riders cornering at the
> limit of traction on mountain roads in this area.
>
That's right! When was the last time you saw someone riding like
this:

http://tinyurl.com/p3f2y

Note, that's Jobst *riding* around a curve on, I believe either Page
Mill Road or Pescadero Road.

> It is usually in junior racing that riders find their limits by
> crashing (without breaking bones) and with most new riders today not
> being youngsters, they rarely test handling limits of tires. That
> appears to be borne out by the many colored tires that have poor wet
> traction that no one seems to notice. Handling appears irrelevant.
>
That's right, just about every 23mm wide tire on the market today is
colored, and is something most of my riding buddies use. I believe I'm
the only one with carbon black tires. Fortunately, it hasn't rain much
in the SF Bay Area in the last year, so not many crashes.

Lou Holtman

01-03-1970, 08:16 PM

jobst.brandt@stanfordalumni.org wrote:
> Lou Holtman writes:
>
>>>> Why bother to equalize the wear for the front and the rear
>>>> tire. Wear out the rear and replace it. Wear out the front and
>>>> replace it. I don't even bother to put the new one in front.
>>>> Puncture resistance and comfort are much more important for me to
>>>> choose a different tire for the rear. Therefor I put a wider tire
>>>> in the back. They last longer too, but that is a bonus.
>
>>> Equalizing the wear was just an incidental possibility for the
>>> particular pairing I am looking at.
>
>>> The reason for wanting a better riding tyre at the front was
>>> because the bike will be used for some racing. So I figured it
>>> might make some sense to keep the tyre with the higher tpi at the
>>> front.
>
>>> If I was just commuting, then I wouldn't have considered from this
>>> angle.
>
>> Do you think Vittoria Open Corsa Evo handles better than a GP4000S?
>> I doubt that.
>
> What do you mean by "handles"? How does one determine whether one
> tire handles better than another? I don't see riders cornering at the
> limit of traction on mountain roads in this area.

That is exactly my point. I doubt if anybody can tell that in their
daily/weekly rides. In their last test Tour Magazine tested tires to the
limit in the wet (until the rider crashed) and the differences in
cornering speeds between the testet tires were quite small. Even the
cornering speed of the worst tire most people never dare to use on a
soaking wet road.

>
> It is usually in junior racing that riders find their limits by
> crashing (without breaking bones) and with most new riders today not
> being youngsters, they rarely test handling limits of tires. That
> appears to be borne out by the many colored tires that have poor wet
> traction that no one seems to notice. Handling appears irrelevant.

All my tires are black(ish) ;-)

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

Sandy

01-03-1970, 08:16 PM

Dans le message de news:47447dd2$0$14144$742ec2ed@news.sonic.net,
jobst.brandt@stanfordalumni.org <jobst.brandt@stanfordalumni.org> a
réfléchi, et puis a déclaré :
> Lou Holtman writes:
>
>>>> Why bother to equalize the wear for the front and the rear
>>>> tire. Wear out the rear and replace it. Wear out the front and
>>>> replace it. I don't even bother to put the new one in front.
>>>> Puncture resistance and comfort are much more important for me to
>>>> choose a different tire for the rear. Therefor I put a wider tire
>>>> in the back. They last longer too, but that is a bonus.
>
>>> Equalizing the wear was just an incidental possibility for the
>>> particular pairing I am looking at.
>
>>> The reason for wanting a better riding tyre at the front was
>>> because the bike will be used for some racing. So I figured it
>>> might make some sense to keep the tyre with the higher tpi at the
>>> front.
>
>>> If I was just commuting, then I wouldn't have considered from this
>>> angle.
>
>> Do you think Vittoria Open Corsa Evo handles better than a GP4000S?
>> I doubt that.
>
> What do you mean by "handles"? How does one determine whether one
> tire handles better than another? I don't see riders cornering at the
> limit of traction on mountain roads in this area.

I guess if we left you to rewrite all dictionaries, then handling would mean
traction. But it doesn't. So, back to "handling". It is a matter partly
of perception, partly of common style of riding, and partly objectively
measurable.

Try, should you dare meet up with something from the current century,
testing two well thought of tires simply replacing one set with another.
I'll even suggest which ones, which "handle" differently in my use and
experience and the reports from other riders.

The first (and my preferred) is the Michelin Pro2Race. The second is the
Hutchinson Fusion. With the Michelin, my perception is that the transition
from vertical to leaning is very smooth, when compared to the Hutchinson.
Specifically as to the latter, through round points, where one can lean
heavily, I feel [feel, yes] there are brusque points of transition from
vertical to leaning hard. That has something to do with traction (something
measurable, I suspect) but is reported in subjective language concerning the
comfort or ease of achieving the turn. I will go faster the more at ease I
feel.

I have other tire comparisons I could offer, but it's clear to me that
people who speak or write about a tire's handling are reporting something
they actually experience; I trust they are not just mimicing the advertising
copy. Incidentally, I had no prejudice against the Hutchinson product; I
paid my money willingly, wanting to see if there were a tire that would
please me more that the Michelin.

Language is used for communication. It is a living mechanism for that. Go
ahead. Jump the milennium mark.
--
Sandy

The above is guaranteed 100% free of sarcasm,
denigration, snotty remarks, indifference, platitudes, fuming demands that
"you do the math", conceited visions of a better world on wheels according
to [insert NAME here].

datakoll

01-03-1970, 08:16 PM

-

it's well known thse tires failed at 2.5 days.
I mean like everyone knows that where you been?

damyth

01-03-1970, 08:16 PM

On Nov 21, 11:12 am, carlfo...@comcast.net wrote:
> On Wed, 21 Nov 2007 02:16:50 -0800 (PST), "Rik O'Shea"
>
>
>
> <rikos...@yahoo.com> wrote:
>
> >> As an aside, racers often mounted old tires for the most events and
> >> stages in the Tour de France. hoping that the RR would be lower with
> >> the rubber tread worn thinner.
>
> >> Carl Fogel
>
> >As an interesting aside when Tony Rominger won the Giro in 1995 every
> >single rider on this team (that's 9 riders) had both tires changed
> >every second day. The tires were tubular (dont ask me about the
> >logistics of this!) and apparently no one on the team suffered a
> >puncture during the event.
>
> >21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
> >help the mechanics)
>
> Dear Rik,
>
> Teams often replace costly equipment because of strange logic.
>
> With tires, it's hard to see what the point of 2-day replacement is.
>
> The amount of wear in two days of long distance bicycle racing is
> typically trivial for tires. These aren't race-car tires that show
> impressive wear in a few laps--the reduction in tread thickness on a
> road bicycle in 300 miles would be hard to measure with a micrometer.
>
> With slightly worn tread, the tires would be infinitesimally more
> likely to flat, but they'd also roll a tiny bit faster and
> theoretically corner a smidgen better, so it's not even clear whether
> new tires are theoretically better or worse than slightly worn tires.
>
> In any case, I'd be surprised if there was any actual data showing a
> measurable practical change in any quality for 2-day old tires versus
> 3-day old tires. If there is a real advantage, then presumably a daily
> change would be even better.
>
> That's the trouble with most arguments about extremely tiny
> theoretical improvements. Riders and mechanics have only so much time
> and money, so fiddling with increasingly trivial minutiae means less
> time and money for the dull but important matters.
>
> An alternate theory is that 2-day replacement guarantees that
> everything has been checked--no damaged tire, no tire with a slow
> leak, no tubular with a hidden glue problem will be in use long enough
> to cause a problem.
>
> Again, daily replacement would provide an even more thorough check.
>
> Most excessive replacement schedules look like wishful thinking.
> People replace large, visible, and dramatic items in a hopeful rather
> than sensible fashion. Even when there's nothing to be done, we still
> like the illusion that we can do something--and often do it.
>
> I wonder if that Giro team replaced their brake pads every two days?
> The brake pads would wear more than the tires, but both would probably
> work just fine on the third day.
>
> Why not replace the cables every two days?
>
> I suspect that mechanics like to replace tires that often because they
> can do it easily. In the weeks before the race, they can occupy
> themselves building up large stocks of spares and looking busy. During
> the race, they can swap the new wheelsets in quickly, giving
> themselves and the riders the dramatic illusion that a lot of
> important work has been done.
>
> Replacing brake pads and shift cables would be much more work on a
> daily basis and much less likely to give that psychological boost. We
> can "feel" a distinct improvement when we see a brand-new tire, but
> it's harder to notice the difference between a 2-day old and a brand
> new shift cable.
>
> Cheers,
>
> Carl Fogel

You didn't quite hit the nail on the head. Teams replace tires
virtually every day because it takes more time (and _good_ lighting, a
commodity they may not have) to inspect a used tire for embedded
glass, wires, foreign objects, etc., than to replace them. They
don't replace things like brake pads everyday because it's not a
component with a high fail rate (like tires if they were to get
punctured), and they are much easier to inspect due to the limited
surface area compared to tires.

It's not about the wear, it's all about minimizing potential down
time, more or less based on cost/benefit.

Sandy

01-03-1970, 08:16 PM

Dans le message de news:37u8k3929qlf0oqe59onsvdouq0fn3rc03@4ax.com,
carlfogel@comcast.net <carlfogel@comcast.net> a réfléchi, et puis a déclaré
:

[big general snip]
>
> Cheers,
>
> Carl Fogel

So, you figure the guys working on the bikes every day after a major tour
are going to take the time to microscopically examine the tread depth,
carcass bruises, cuts, embedded gravel, etc.?

Interesting to imagine how you would spend your evenings as a mechanic on
tour, having to clean and service bikes for the next day. between 3 and 5
complete bike cleanings and sets of adjustments and parts exchanges. You
think it's worth the possible loss of riders the next day by sending them
out again with old tires?

Do you watch any of these races? We know you can't do them. Well, riders
don't *****foot around gravel, they bang over curbs, lean hard, skid, cross
crappy paving, bounce on cobbles, smash into potholes, sometimes go down.
The tires take a pretty good beating.

Tell you what. My team mechanics can feel free to assure me a safe ride
tomorrow. You can just roll out the trusty RoadRasher and roll on and on
and on.

Just don't expect the rest of us to wait for you at the finish, or to give
you a spare when you need it, not even Slime or a patch. We won't have any
of those.

Try writing for your own context for a change. Slow, chubby, fabricator
group.
--
Sandy
--
Il n'est aucune sorte de sensation qui soit plus vive
que celle de la douleur ; ses impressions sont sûres,
elles ne trompent point comme celles du plaisir.
- de Sade.

jobst.brandt@stanfordalumni.org

01-03-1970, 08:16 PM

bfd who? writes:

>>>>> Why bother to equalize the wear for the front and the rear tire.
>>>>> Wear out the rear and replace it. Wear out the front and
>>>>> replace it. I don't even bother to put the new one in front.
>>>>> Puncture resistance and comfort are much more important for me
>>>>> to choose a different tire for the rear. Therefor I put a wider
>>>>> tire in the back. They last longer too, but that is a bonus.

>>>> Equalizing the wear was just an incidental possibility for the
>>>> particular pairing I am looking at.

>>>> The reason for wanting a better riding tyre at the front was
>>>> because the bike will be used for some racing. So I figured it
>>>> might make some sense to keep the tyre with the higher tpi at the
>>>> front.

>>>> If I was just commuting, then I wouldn't have considered from
>>>> this angle.

>>> Do you think Vittoria Open Corsa Evo handles better than a
>>> GP4000S? I doubt that.

>> What do you mean by "handles"? How does one determine whether one
>> tire handles better than another? I don't see riders cornering at
>> the limit of traction on mountain roads in this area.

> That's right! When was the last time you saw someone riding like
> this:

http://tinyurl.com/p3f2y

> Note, that's Jobst *riding* around a curve on, I believe either Page
> Mill Road or Pescadero Road.

Make that the first turn descending Haskins Hill toward Pescadero.

Jobst Brandt

Tom Sherman

01-03-1970, 08:16 PM

bfd ? wrote:
> ...
> That's right! When was the last time you saw someone riding like
> this:
>
> http://tinyurl.com/p3f2y
>
> Note, that's Jobst *riding* around a curve on, I believe either Page
> Mill Road or Pescadero Road....

The Famous Yellow Bicycle! Now you made Sorni's day!

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

jobst.brandt@stanfordalumni.org

01-03-1970, 08:16 PM

Lou Holtman writes:

>>>>> Why bother to equalize the wear for the front and the rear tire.
>>>>> Wear out the rear and replace it. Wear out the front and
>>>>> replace it. I don't even bother to put the new one in front.
>>>>> Puncture resistance and comfort are much more important for me
>>>>> to choose a different tire for the rear. Therefor I put a wider
>>>>> tire in the back. They last longer too, but that is a bonus.

>>>> Equalizing the wear was just an incidental possibility for the
>>>> particular pairing I am looking at.

>>>> The reason for wanting a better riding tyre at the front was
>>>> because the bike will be used for some racing. So I figured it
>>>> might make some sense to keep the tyre with the higher tpi at the
>>>> front.

>>>> If I was just commuting, then I wouldn't have considered from
>>>> this angle.

>>> Do you think Vittoria Open Corsa Evo handles better than a
>>> GP4000S? I doubt that.

>> What do you mean by "handles"? How does one determine whether one
>> tire handles better than another? I don't see riders cornering at
>> the limit of traction on mountain roads in this area.

> That is exactly my point. I doubt if anybody can tell that in their
> daily/weekly rides. In their last test Tour Magazine tested tires
> to the limit in the wet (until the rider crashed) and the
> differences in cornering speeds between the tested tires were quite
> small. Even the cornering speed of the worst tire most people never
> dare to use on a soaking wet road.

That sounds like a crude way of testing tires. For that, I deigned a
machine for Avocet with a 6-foot diameter paved drum and a pneumatic
piston load for the tire being tested, to give RR and traction. The
fork was mounted on a rotary table to give lean angle with computer
controlled position and a misting nozzle to wet the rolling surface.
Wipe-out angles were precisely measured and recorded. No riders
crashes or tire expectation were involved.

>> It is usually in junior racing that riders find their limits by
>> crashing (without breaking bones) and with most new riders today
>> not being youngsters, they rarely test handling limits of tires.
>> That appears to be borne out by the many colored tires that have
>> poor wet traction that no one seems to notice. Handling appears
>> irrelevant.

> All my tires are black(ish) ;-)

That's not good enough. There are tires made that have no carbon
black but coloring to suit, including "black".

Jobst Brandt

datakoll

01-03-1970, 08:16 PM

On Nov 21, 2:38 pm, Lou Holtman <lholremovet...@planet.nl> wrote:
> jobst.bra...@stanfordalumni.org wrote:
> > Lou Holtman writes:
>
> >>>> Why bother to equalize the wear for the front and the rear
> >>>> tire. Wear out the rear and replace it. Wear out the front and
> >>>> replace it. I don't even bother to put the new one in front.
> >>>> Puncture resistance and comfort are much more important for me to
> >>>> choose a different tire for the rear. Therefor I put a wider tire
> >>>> in the back. They last longer too, but that is a bonus.
>
> >>> Equalizing the wear was just an incidental possibility for the
> >>> particular pairing I am looking at.
>
> >>> The reason for wanting a better riding tyre at the front was
> >>> because the bike will be used for some racing. So I figured it
> >>> might make some sense to keep the tyre with the higher tpi at the
> >>> front.
>
> >>> If I was just commuting, then I wouldn't have considered from this
> >>> angle.
>
> >> Do you think Vittoria Open Corsa Evo handles better than a GP4000S?
> >> I doubt that.
>
> > What do you mean by "handles"? How does one determine whether one
> > tire handles better than another? I don't see riders cornering at the
> > limit of traction on mountain roads in this area.
>
> That is exactly my point. I doubt if anybody can tell that in their
> daily/weekly rides. In their last test Tour Magazine tested tires to the
> limit in the wet (until the rider crashed) and the differences in
> cornering speeds between the testet tires were quite small. Even the
> cornering speed of the worst tire most people never dare to use on a
> soaking wet road.
>
>
>
> > It is usually in junior racing that riders find their limits by
> > crashing (without breaking bones) and with most new riders today not
> > being youngsters, they rarely test handling limits of tires. That
> > appears to be borne out by the many colored tires that have poor wet
> > traction that no one seems to notice. Handling appears irrelevant.
>
> All my tires are black(ish) ;-)
>
> Lou
> --
> Posted by news://news.nb.nu (http://www.nb.nu)- Hide quoted text -
>
> - Show quoted text -

the market's saleable variety sez the results are small: a killer tire
would put the rest on the trailer. A developing research field
capable of dumping the product into the market would go one tire few
tires many tires one tire few tires...
but some riders continue buying cheap worthless tires, no reason why
that's not true near the local upper levels.

Ben Pfaff

01-03-1970, 08:16 PM

jobst.brandt@stanfordalumni.org writes:

> That's not good enough. There are tires made that have no carbon
> black but coloring to suit, including "black".

Interesting. How do I tell whether my tires were made with
carbon black or were merely colored black?
--
"...dans ce pays-ci il est bon de tuer de temps en temps un amiral
pour encourager les autres."
--Voltaire, _Candide_

datakoll

01-03-1970, 08:16 PM

On Nov 21, 2:54 pm, jobst.bra...@stanfordalumni.org wrote:
> Lou Holtman writes:
> >>>>> Why bother to equalize the wear for the front and the rear tire.
> >>>>> Wear out the rear and replace it. Wear out the front and
> >>>>> replace it. I don't even bother to put the new one in front.
> >>>>> Puncture resistance and comfort are much more important for me
> >>>>> to choose a different tire for the rear. Therefor I put a wider
> >>>>> tire in the back. They last longer too, but that is a bonus.
> >>>> Equalizing the wear was just an incidental possibility for the
> >>>> particular pairing I am looking at.
> >>>> The reason for wanting a better riding tyre at the front was
> >>>> because the bike will be used for some racing. So I figured it
> >>>> might make some sense to keep the tyre with the higher tpi at the
> >>>> front.
> >>>> If I was just commuting, then I wouldn't have considered from
> >>>> this angle.
> >>> Do you think Vittoria Open Corsa Evo handles better than a
> >>> GP4000S? I doubt that.
> >> What do you mean by "handles"? How does one determine whether one
> >> tire handles better than another? I don't see riders cornering at
> >> the limit of traction on mountain roads in this area.
> > That is exactly my point. I doubt if anybody can tell that in their
> > daily/weekly rides. In their last test Tour Magazine tested tires
> > to the limit in the wet (until the rider crashed) and the
> > differences in cornering speeds between the tested tires were quite
> > small. Even the cornering speed of the worst tire most people never
> > dare to use on a soaking wet road.
>
> That sounds like a crude way of testing tires. For that, I deigned a
> machine for Avocet with a 6-foot diameter paved drum and a pneumatic
> piston load for the tire being tested, to give RR and traction. The
> fork was mounted on a rotary table to give lean angle with computer
> controlled position and a misting nozzle to wet the rolling surface.
> Wipe-out angles were precisely measured and recorded. No riders
> crashes or tire expectation were involved.
>
> >> It is usually in junior racing that riders find their limits by
> >> crashing (without breaking bones) and with most new riders today
> >> not being youngsters, they rarely test handling limits of tires.
> >> That appears to be borne out by the many colored tires that have
> >> poor wet traction that no one seems to notice. Handling appears
> >> irrelevant.
> > All my tires are black(ish) ;-)
>
> That's not good enough. There are tires made that have no carbon
> black but coloring to suit, including "black".
>
> Jobst Brandt- Hide quoted text -
>
> - Show quoted text -

JB, what's on the drawing board for a computerized two wheel and
framed device?

can you tell us what the single wheel tester cost?

How did the human testor(s) results differ from the machine?

jobst.brandt@stanfordalumni.org

01-03-1970, 08:17 PM

Ben Pfaff writes:

>> That's not good enough. There are tires made that have no carbon
>> black but coloring to suit, including "black".

> Interesting. How do I tell whether my tires were made with
> carbon black or were merely colored black?

If the store has the same tire in different colors, that's a clue.
However, carbon black rubber has a matte dark gray color and is not
slick and smooth. If the tire is glossy black, like one that has been
sprayed for a car show, it is probably colored black rather than
carbon.

Jobst Brandt

Artoi

01-03-1970, 08:17 PM

In article <4744a36e$0$14107$742ec2ed@news.sonic.net>,
jobst.brandt@stanfordalumni.org wrote:

> Ben Pfaff writes:
>
> >> That's not good enough. There are tires made that have no carbon
> >> black but coloring to suit, including "black".
>
> > Interesting. How do I tell whether my tires were made with
> > carbon black or were merely colored black?
>
> If the store has the same tire in different colors, that's a clue.
> However, carbon black rubber has a matte dark gray color and is not
> slick and smooth. If the tire is glossy black, like one that has been
> sprayed for a car show, it is probably colored black rather than
> carbon.

Interesting point here. Conti brought out their Chili compound earlier
this year for improved grip and what have you. It's black only. So their
new GP4000+Chili and GP4000S won't have any colour choice.
--

carlfogel@comcast.net

01-03-1970, 08:17 PM

On Wed, 21 Nov 2007 14:10:39 -0800 (PST), damyth
<mdk.10.damyth@spamgourmet.com> wrote:

>On Nov 21, 11:12 am, carlfo...@comcast.net wrote:
>> On Wed, 21 Nov 2007 02:16:50 -0800 (PST), "Rik O'Shea"
>>
>>
>>
>> <rikos...@yahoo.com> wrote:
>>
>> >> As an aside, racers often mounted old tires for the most events and
>> >> stages in the Tour de France. hoping that the RR would be lower with
>> >> the rubber tread worn thinner.
>>
>> >> Carl Fogel
>>
>> >As an interesting aside when Tony Rominger won the Giro in 1995 every
>> >single rider on this team (that's 9 riders) had both tires changed
>> >every second day. The tires were tubular (dont ask me about the
>> >logistics of this!) and apparently no one on the team suffered a
>> >puncture during the event.
>>
>> >21 days/2 * 9 riders * 2 tires = 180 tires used during the event (God
>> >help the mechanics)
>>
>> Dear Rik,
>>
>> Teams often replace costly equipment because of strange logic.
>>
>> With tires, it's hard to see what the point of 2-day replacement is.
>>
>> The amount of wear in two days of long distance bicycle racing is
>> typically trivial for tires. These aren't race-car tires that show
>> impressive wear in a few laps--the reduction in tread thickness on a
>> road bicycle in 300 miles would be hard to measure with a micrometer.
>>
>> With slightly worn tread, the tires would be infinitesimally more
>> likely to flat, but they'd also roll a tiny bit faster and
>> theoretically corner a smidgen better, so it's not even clear whether
>> new tires are theoretically better or worse than slightly worn tires.
>>
>> In any case, I'd be surprised if there was any actual data showing a
>> measurable practical change in any quality for 2-day old tires versus
>> 3-day old tires. If there is a real advantage, then presumably a daily
>> change would be even better.
>>
>> That's the trouble with most arguments about extremely tiny
>> theoretical improvements. Riders and mechanics have only so much time
>> and money, so fiddling with increasingly trivial minutiae means less
>> time and money for the dull but important matters.
>>
>> An alternate theory is that 2-day replacement guarantees that
>> everything has been checked--no damaged tire, no tire with a slow
>> leak, no tubular with a hidden glue problem will be in use long enough
>> to cause a problem.
>>
>> Again, daily replacement would provide an even more thorough check.
>>
>> Most excessive replacement schedules look like wishful thinking.
>> People replace large, visible, and dramatic items in a hopeful rather
>> than sensible fashion. Even when there's nothing to be done, we still
>> like the illusion that we can do something--and often do it.
>>
>> I wonder if that Giro team replaced their brake pads every two days?
>> The brake pads would wear more than the tires, but both would probably
>> work just fine on the third day.
>>
>> Why not replace the cables every two days?
>>
>> I suspect that mechanics like to replace tires that often because they
>> can do it easily. In the weeks before the race, they can occupy
>> themselves building up large stocks of spares and looking busy. During
>> the race, they can swap the new wheelsets in quickly, giving
>> themselves and the riders the dramatic illusion that a lot of
>> important work has been done.
>>
>> Replacing brake pads and shift cables would be much more work on a
>> daily basis and much less likely to give that psychological boost. We
>> can "feel" a distinct improvement when we see a brand-new tire, but
>> it's harder to notice the difference between a 2-day old and a brand
>> new shift cable.
>>
>> Cheers,
>>
>> Carl Fogel
>
>You didn't quite hit the nail on the head. Teams replace tires
>virtually every day because it takes more time (and _good_ lighting, a
>commodity they may not have) to inspect a used tire for embedded
>glass, wires, foreign objects, etc., than to replace them. They
>don't replace things like brake pads everyday because it's not a
>component with a high fail rate (like tires if they were to get
>punctured), and they are much easier to inspect due to the limited
>surface area compared to tires.
>
>It's not about the wear, it's all about minimizing potential down
>time, more or less based on cost/benefit.

Dear Damyth,

Sorry, but I think that replacing bicycle tires every other day on a
long distance event is all about doing _something_ even when it
doesn't make sense.

I'm willing to learn otherwise, but . . .

The team replaced the tires every other day, not every day.

If replacement was a substitute for inspection, why would they risk
disaster every other day?

Did they have enough time to inspect the tires on Monday, but were so
rushed that they had replace them blindly on Tuesday?

If a team;s mechanics haven't got enough time to spin two tires
slowly on nine bikes every two days (and enough money for a flashlight
if they plans to do it in the dark), what on earth are they doing the
rest of the time? Whittling new bearings by hand?

For that matter, how much time can you save removing and replacing 18
quick release wheels versus inspecting 18 tires already in place?

Remember, you have to haul 18 new wheels out of storage in a cramped
van or truck to the bikes, remove the old wheels, pop the new ones in,
and carry 18 old wheels back to storage (or toss them over the fence
if that's cost effective).

Teams build up enormous stocks of spare wheels because they know how
to do it, they like to do it, and they have plenty of time between
events to do it.

Look at all those spare wheels, ready to go!

Swapping in whole new sets of wheels and tires every other day
certainly makes everyone feel good, but I'll be astonished if anyone
comes up with actual figures showing a cost-benefit advantage for
replacing the wheels and tires every 300 miles. That is, fewer flats,
better rolling resistance, or superior cornering.

Of course, we may have stumbled onto the dark secret of professional
racing. Maybe modern tubular glue weakens so much that the tires fall
off after two days, whether they're inspected or not.

:-)

As Parkinson explained, work expands to fill the time available for
its completion.

I suspect that if a team gives its mechanics enough time and not
enough else to do, they will come up with ever more complicated
tubular gluing routines (some procedures described on RBT occupy
several days) and will fill ever more racks in the support trucks with
increasing numbers of spare wheelsets, which they wll then swap in as
often as they can manage, sincerely believing that they're doing
something that _really_ needs doing.

But I could be wrong.

I'd just like a better theory than the claim that professional
mechanics can't spare the time to glance at tires every two days.

Cheers,

Carl Fogel

Sandy

01-03-1970, 08:17 PM

Dans le message de news:2fb9k3dc2bo04722cr9u8gfhgpvhmtpohc@4ax.com,
carlfogel@comcast.net <carlfogel@comcast.net> a réfléchi, et puis a déclaré
:

SADLY HE CONTINUES TO WRITE FROM THE DEPTHS OF IGNORANCE, BUT ....

> On Wed, 21 Nov 2007 14:10:39 -0800 (PST), damyth
> <mdk.10.damyth@spamgourmet.com> wrote:
>
>> On Nov 21, 11:12 am, carlfo...@comcast.net wrote:
>>> On Wed, 21 Nov 2007 02:16:50 -0800 (PST), "Rik O'Shea"
>>>
>>>
>>>
>>> <rikos...@yahoo.com> wrote:
>>>
>>>>> As an aside, racers often mounted old tires for the most events
>>>>> and stages in the Tour de France. hoping that the RR would be
>>>>> lower with the rubber tread worn thinner.
>>>
>>>>> Carl Fogel
>>>
>>>> As an interesting aside when Tony Rominger won the Giro in 1995
>>>> every single rider on this team (that's 9 riders) had both tires
>>>> changed every second day. The tires were tubular (dont ask me
>>>> about the logistics of this!) and apparently no one on the team
>>>> suffered a puncture during the event.
>>>
>>>> 21 days/2 * 9 riders * 2 tires = 180 tires used during the event
>>>> (God help the mechanics)
>>>
>>> Dear Rik,
>>>
>>> Teams often replace costly equipment because of strange logic.
>>>
>>> With tires, it's hard to see what the point of 2-day replacement is.
>>>
>>> The amount of wear in two days of long distance bicycle racing is
>>> typically trivial for tires. These aren't race-car tires that show
>>> impressive wear in a few laps--the reduction in tread thickness on a
>>> road bicycle in 300 miles would be hard to measure with a
>>> micrometer.
>>>
>>> With slightly worn tread, the tires would be infinitesimally more
>>> likely to flat, but they'd also roll a tiny bit faster and
>>> theoretically corner a smidgen better, so it's not even clear
>>> whether new tires are theoretically better or worse than slightly
>>> worn tires.
>>>
>>> In any case, I'd be surprised if there was any actual data showing a
>>> measurable practical change in any quality for 2-day old tires
>>> versus 3-day old tires. If there is a real advantage, then
>>> presumably a daily change would be even better.
>>>
>>> That's the trouble with most arguments about extremely tiny
>>> theoretical improvements. Riders and mechanics have only so much
>>> time and money, so fiddling with increasingly trivial minutiae
>>> means less time and money for the dull but important matters.
>>>
>>> An alternate theory is that 2-day replacement guarantees that
>>> everything has been checked--no damaged tire, no tire with a slow
>>> leak, no tubular with a hidden glue problem will be in use long
>>> enough to cause a problem.
>>>
>>> Again, daily replacement would provide an even more thorough check.
>>>
>>> Most excessive replacement schedules look like wishful thinking.
>>> People replace large, visible, and dramatic items in a hopeful
>>> rather than sensible fashion. Even when there's nothing to be done,
>>> we still like the illusion that we can do something--and often do
>>> it.
>>>
>>> I wonder if that Giro team replaced their brake pads every two days?
>>> The brake pads would wear more than the tires, but both would
>>> probably work just fine on the third day.
>>>
>>> Why not replace the cables every two days?
>>>
>>> I suspect that mechanics like to replace tires that often because
>>> they can do it easily. In the weeks before the race, they can occupy
>>> themselves building up large stocks of spares and looking busy.
>>> During the race, they can swap the new wheelsets in quickly, giving
>>> themselves and the riders the dramatic illusion that a lot of
>>> important work has been done.
>>>
>>> Replacing brake pads and shift cables would be much more work on a
>>> daily basis and much less likely to give that psychological boost.
>>> We can "feel" a distinct improvement when we see a brand-new tire,
>>> but it's harder to notice the difference between a 2-day old and a
>>> brand new shift cable.
>>>
>>> Cheers,
>>>
>>> Carl Fogel
>>
>> You didn't quite hit the nail on the head. Teams replace tires
>> virtually every day because it takes more time (and _good_ lighting,
>> a commodity they may not have) to inspect a used tire for embedded
>> glass, wires, foreign objects, etc., than to replace them. They
>> don't replace things like brake pads everyday because it's not a
>> component with a high fail rate (like tires if they were to get
>> punctured), and they are much easier to inspect due to the limited
>> surface area compared to tires.
>>
>> It's not about the wear, it's all about minimizing potential down
>> time, more or less based on cost/benefit.
>
> Dear Damyth,
>
> Sorry, but I think that replacing bicycle tires every other day on a
> long distance event is all about doing _something_ even when it
> doesn't make sense.
>
> I'm willing to learn otherwise, but . . .
>
> The team replaced the tires every other day, not every day.
>
> If replacement was a substitute for inspection, why would they risk
> disaster every other day?

No. They have something called experience, which they rely on.
>
> Did they have enough time to inspect the tires on Monday, but were so
> rushed that they had replace them blindly on Tuesday?

No, they will inspect all tires every day. That's not the same as changing
them. I feel so warmly comfortable that should they notice a nice big cut,
they would do their jobs. Don't you agree?
>
> If a team;s mechanics haven't got enough time to spin two tires
> slowly on nine bikes every two days (and enough money for a flashlight
> if they plans to do it in the dark), what on earth are they doing the
> rest of the time? Whittling new bearings by hand?

Perversion of the original facts. They do have the time. They do do that.
They simply have a good feeling for what replacement strategy is optimal.
>
> For that matter, how much time can you save removing and replacing 18
> quick release wheels versus inspecting 18 tires already in place?

All tires come off all bikes every time they go out. Another false premise
of yours. Go see a pro race. Observe. Learn. Before you wear out another
keyboard.

> Remember, you have to haul 18 new wheels out of storage in a cramped
> van or truck to the bikes, remove the old wheels, pop the new ones in,
> and carry 18 old wheels back to storage (or toss them over the fence
> if that's cost effective).

They are paid to do even more onerous and mindless work. All in the job.

> Teams build up enormous stocks of spare wheels because they know how
> to do it, they like to do it, and they have plenty of time between
> events to do it.

Observe. Learn. Then write. Again, you have no actual knowledge. Fact.
>
> Look at all those spare wheels, ready to go!
>
> Swapping in whole new sets of wheels and tires every other day
> certainly makes everyone feel good, but I'll be astonished if anyone
> comes up with actual figures showing a cost-benefit advantage for
> replacing the wheels and tires every 300 miles. That is, fewer flats,
> better rolling resistance, or superior cornering.

I am sure they have these analyses, and will not share them with you.
Because you would never, ever go away again. The indices of their strategy
are more likely based on _experience_ again. Some humans are content to
rely on experience. Even of avoiding unknown experiences. Would you jump
off a 100 foot cliff? Using your logic, you would have to actually collect
data on significant numbers of jumpers before you would hazard a guess. My
suggestion - be the first off the cliff. Please.
>
> As Parkinson explained, work expands to fill the time available for
> its completion.

This _is_ autobiographical and self-loathing, yes?
>
> But I could be wrong.

Insight at last.

Like the outliers of statistical analysis. You allow your own paradigm of
predictability to be enhanced by the stray quark.
--
Les faits relatés ici ne sont que pure fiction, et ne sauraient être
utilisés ou rapprochés d'une situation réelle existant ou ayant
existée

jobst.brandt@stanfordalumni.org

01-03-1970, 08:17 PM

Morten Reippuert Knudsen writes:

>> I am wondering what people think of running different tyres front
>> and back on a road bike? Recently the rear of my pair of Vittoria
>> Open Corsa Evo Cx has worn thin and suffered a number of flats yet
>> the front one is still in pretty good shape. So I am wondering
>> what if I paired the Vittoria with a more puncture and wear
>> resistant Conti GP4000 at the rear? Note here that the Vittoria is
>> considered to be a race tyre that wears pretty quickly.

>> So the logic is as follows.

>> Given that,
>> 1) Rear tyre's wear rate is greater.
>> 2) Front tyre is more important for bike control.
>> 3) High TPI tyres gives a "better" ride.

> more road contact area an more flexible sidewalls will provide you
> with a more grip.

How much is good and how much is enough. I haven't seen riders
skidding on climbs or descents recently and small cross section tires
are IN.

> Notice that Vittoria counts the threads double, witch means that
> 290 is equal to 145 compared to Michelins with 127 threads.

They count the total ply count and I'm not even sure whether they know
what those numbers are supposed to mean. Tire cords are threads and
their diameter is not as easily measured as that of a single wire
strands, so giving how many of these can be laid side-by-side in a
tire ply was a reasonable measure. The thinner a silk thread in a
tubular tire was, the lower the casing flex losses were, but threads
per inch is a sham these days.

> my choice for the front is a 25mm Michelin Pro2race, the grip and
> smoothness is similar to Vittorias now discontinued 23mm Open
> Extreeme witch i have always found to be a nicer tyre than the CX's.

I doubt you can even loosely quantify grip while smoothness is highly
sensitive to inflation pressure, so your qualitative claim is left
floating on air.

> The Michelin is also very puncture resistent when riding on dry
> roads and lasts at least twice the km count of the Vittorias. I
> haved tried the Conti 4000, but i never liked the 3000's so im
> sticking with the Michelins.

Puncture resistant against what? I'll match your test with any broken
beer bottle on the road or a ride through puncture vine. I don't
believe you have valid statistical testing from my experience of
having ridden racing tubulars for many years and subsequently
clinchers from all the major manufacturers. My puncture experience
has little statistical repetition. Most of my more than 2000mile
tours of the Alps didn't require even pumping a tire once after I
stopped riding Clement tubulars with latex tubes.

> If you want a durable rear tire i can recocment Michelins Krylion
> carbon. For the rear the isn't much difference between 23 and 25mm.
> For the front 25mm has a better grip, and better comfort -
> especially the pro2race.

> as of riling resistance the 25mm pro2race actually has lower
> resistance than the 23mm version. The weight is almost the same.
> Among other top level tires 25mm are noticeable heavier than 23mm.

On what do you base this advice? There are no quantified comparisons
anywhere in your promotion of one tire over another.

Jobst Brandt

Artoi

01-03-1970, 08:17 PM

In article <6kpe15-9lg.ln1@wm.reippuert.dk>,
Morten Reippuert Knudsen <spam@reippuert.dk> wrote:

> Notice that vittoria counts the threads doubble, witch means that 290
> is equal to 145 compared to michelins with 127 threads.

Really? I'll have to check this one out. Shocked to hear this as a
matter of fact.
--

jobst.brandt@stanfordalumni.org

01-03-1970, 08:17 PM

Gene Daniels writes:

>> That sounds like a crude way of testing tires. For that, I deigned
>> a machine for Avocet with a 6-foot diameter paved drum and a
>> pneumatic piston load for the tire being tested, to give RR and
>> traction. The fork was mounted on a rotary table to give lean
>> angle with computer controlled position and a misting nozzle to wet
>> the rolling surface. Wipe-out angles were precisely measured and
>> recorded. No riders crashes or tire expectation were involved.

>>>> It is usually in junior racing that riders find their limits by
>>>> crashing (without breaking bones) and with most new riders today
>>>> not being youngsters, they rarely test handling limits of tires.
>>>> That appears to be borne out by the many colored tires that have
>>>> poor wet traction that no one seems to notice. Handling appears
>>>> irrelevant.

>>> All my tires are black(ish).

>> That's not good enough. There are tires made that have no carbon
>> black but coloring to suit, including "black".

> JB, what's on the drawing board for a computerized two wheel and
> framed device?

> can you tell us what the single wheel tester cost?

This was part of the tire program at Avocet and when that project was
ended, no further effort was made to design test equipment.

> How did the human tester(s) results differ from the machine?

Not much human testing... to the limit was done. My experience was
that at about 45 degrees tires wash out. The first tests were done
riding across a tilted paved plywood ramp with adjustable slope.
Rider influence showed such a scatter of results that a machine needed
to be built... and it was.

Jobst Brandt