700/23 vs 700/25 tires ?

On Jan 28, 9:27*pm, jeffreybike wrote:
Is there any real difference between 23mm and 25mm tires as far as
speed. Will 2mm make you that slower or faster?
thanks, Jeff

973 posts with this one. Maybe this one should not count. Carl, can
you do one of your internet searches to determine the number of
rec.bicycle.tech threads which have reached 1000 posts? I'm sure this
one will make it in another day or two.

Robert Chung wrote:
Oh crap, I forgot the link. Here it is:
http://forum.slowtwitch.com/cgi-bin/...view_flat;post...
That thread also mentions some on-the-road validation of Al Morrison's Crr
data. All in all, it brought together some theoretical modeling, a bunch of
empirical testing, some analysis, and validation of the models and tests in
real world results. There're also plenty of responding to questions about
the tests, and some discussion of precision. One interesting example: the
method showed there was something odd about the results so Tom took off the
tires and realized the tubes were butyl rather than latex. A butyl-latex
correction based on Al's data brought everything back into line.
So, on the one hand, we have people who have done modeling, data collection,
analysis, and validation. On the other hand, there's Frank, who's obsessed
about a decades-old Shimano brochure, Carl, who paws through photos looking
for wris****ches, and Tim, who refuses to look at tables comparing tire
rolling resistance. Hmmm. Tough call.

Frank Krygowski wrote:
Yet more TT and tri stuff. That's all you understand, I see.
Do you really think any tiny difference in TT times must be equally
valuable in a road race? In a crit race? In a recreational ride?

Tour of California Stage Four Merced to Clovis 115 miles and the end
looked justthisdarnedclose:
http://asp.usatoday.com/_common/_scr...ingx-large.jpg

http://tinyurl.com/bek7g8

What's the percent elapsed time difference between victory and 'else'?
(115 miles over a tire width or two)

Could you imagine (for example) a tire inflation difference that great,
aside from the tires themselves?
Could you agree that a relatively niggling minor difference (be it
equipment, mood, aerodynamics, food, drugs) between two highly skilled
riders could make that difference?
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

"Robert Chung" wrote in message
...
Frank Krygowski wrote:

Do you really think any tiny difference in TT times must be equally
valuable in a road race? In a crit race? In a recreational ride?

Frank, you ignorant slut, the TT times were a real-world validation of the
models, data collection, and analysis used to estimate CdA and Crr
changes. Crr and CdA advantages are always there. In fact, drag benefits
(whether aero or rolling resistance) have the potential to mean even
greater absolute time differences for non-racers on recreational rides.
Hmmm. That last sentence sounds familiar. Where have we heard it before?
Could you please repeat that last part?
Just to be sure I get it.
The stuff about non-competition riding....
Maybe you could type slower?
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

On Feb 19, 2:04*pm, A Muzi wrote:
Robert Chung wrote:
Oh crap, I forgot the link. Here it is:
http://forum.slowtwitch.com/cgi-bin/...view_flat;post...
That thread also mentions some on-the-road validation of Al Morrison's Crr
data. All in all, it brought together some theoretical modeling, a bunch of
empirical testing, some analysis, and validation of the models and tests in
real world results. There're also plenty of responding to questions about
the tests, and some discussion of precision. One interesting example: the
method showed there was something odd about the results so Tom took off the
tires and realized the tubes were butyl rather than latex. A butyl-latex
correction based on Al's data brought everything back into line.
So, on the one hand, we have people who have done modeling, data collection,
analysis, and validation. On the other hand, there's Frank, who's obsessed
about a decades-old Shimano brochure, Carl, who paws through photos looking
for wris****ches, and Tim, who refuses to look at tables comparing tire
rolling resistance. Hmmm. Tough call.
Frank Krygowski wrote:
Yet more TT and tri stuff. *That's all you understand, I see.
Do you really think any tiny difference in TT times must be equally
valuable in a road race? *In a crit race? *In a recreational ride?

Tour of California Stage Four Merced to Clovis 115 miles and the end
looked justthisdarnedclose:http://asp.usatoday.com/_common/_scr...px?width=490&h...

http://tinyurl.com/bek7g8

What's the percent elapsed time difference between victory and 'else'?
(115 miles over a tire width or two)

Could you imagine (for example) a tire inflation difference that great,
aside from the tires themselves?
Could you agree that a relatively niggling minor difference (be it
equipment, mood, aerodynamics, food, drugs) between two highly skilled
riders could make that difference?
--
Andrew Muzi
* www.yellowjersey.org/
* Open every day since 1 April, 1971- Hide quoted text -

- Show quoted text -

But can a close race like that really be attributed to the
aerodynamics being discussed in this thread? Or equipment
differences? Cavendish had a better leadout train to put him into the
best position near the line and started his sprint at the correct
moment. Whereas Boonen was just a fraction of a fraction of a second
too slow to start his sprint. Cavendish just happened to start the
sprint at the right moment, and Boonen did not. Best/fastest
equipment in the world is worthless if your timing is not right.

On Thu, 19 Feb 2009 14:04:42 -0600, A Muzi
wrote:

Robert Chung wrote:
Oh crap, I forgot the link. Here it is:
http://forum.slowtwitch.com/cgi-bin/...view_flat;post...
That thread also mentions some on-the-road validation of Al Morrison's Crr
data. All in all, it brought together some theoretical modeling, a bunch of
empirical testing, some analysis, and validation of the models and tests in
real world results. There're also plenty of responding to questions about
the tests, and some discussion of precision. One interesting example: the
method showed there was something odd about the results so Tom took off the
tires and realized the tubes were butyl rather than latex. A butyl-latex
correction based on Al's data brought everything back into line.
So, on the one hand, we have people who have done modeling, data collection,
analysis, and validation. On the other hand, there's Frank, who's obsessed
about a decades-old Shimano brochure, Carl, who paws through photos looking
for wris****ches, and Tim, who refuses to look at tables comparing tire
rolling resistance. Hmmm. Tough call.

Frank Krygowski wrote:
Yet more TT and tri stuff. That's all you understand, I see.
Do you really think any tiny difference in TT times must be equally
valuable in a road race? In a crit race? In a recreational ride?

Tour of California Stage Four Merced to Clovis 115 miles and the end
looked justthisdarnedclose:
http://asp.usatoday.com/_common/_scr...ingx-large.jpg

http://tinyurl.com/bek7g8

What's the percent elapsed time difference between victory and 'else'?
(115 miles over a tire width or two)

Could you imagine (for example) a tire inflation difference that great,
aside from the tires themselves?
Could you agree that a relatively niggling minor difference (be it
equipment, mood, aerodynamics, food, drugs) between two highly skilled
riders could make that difference?

Dear Andrew,

I've mentioned Al Morrison's test of four tires on smooth and
bumpy-rollers at presures from 80 to 150 initial psi at 68F in 2007:

http://www.biketechreview.com/tires/...a_BTR_rev1.pdf

I don't think anyone even commented (except Frank, who noted that the
link to the discussion and details is dead).

The tire temperatures rose 20F to 40F during the roller test,
depending on the test and the rollers, so the tire pressures must have
risen, too, something that they don't do in real riding. Al's
corrections may take care of the pressure rise as well as the tread
temperature change.

The rightmost column seems to be the summary column.

***

In the the rightmost column, tires varied 4.5, 1.4, 6.9, and 6.1 watts
over the wide 80 to 150 psi test range.

The best theoretical pressures were 150, 150 or 80 (tied--weird), 150,
and 110 psi.

***

From 100 to 120 psi, the range was only 1.6, 0.5, 0.6, and 0.5 watts.

Within that arbitrary range, the best psi was 120, 100, 110, and 110.

How the tires would have cornered would probably vary according to
pressure and bumpiness, too, just as the ride would be awful,
acceptable, or comfortable.

***

I wonder what pressure posters would choose for any of those four
specific tires and why?

I also wonder how many riders apply that data, as opposed to using a
seat-of-the-pants, press-with-a-thumb, my-gauge-ought-to-be-right sort
of approach to tire pressure?

My guess is that most riders just use a pressure that they like,
without much continuing personal testing and without much reference to
any test results.

Cheers,

Carl Fogel

On Thu, 19 Feb 2009 11:58:49 -0800 (PST), "
wrote:

On Jan 28, 9:27*pm, jeffreybike wrote:
Is there any real difference between 23mm and 25mm tires as far as
speed. Will 2mm make you that slower or faster?
thanks, Jeff

973 posts with this one. Maybe this one should not count. Carl, can
you do one of your internet searches to determine the number of
rec.bicycle.tech threads which have reached 1000 posts? I'm sure this
one will make it in another day or two.

Dear Russell,

The Microsoft netscan site died a while ago, but someone else might
know of a way to check or else think of a few promising largethreads,
usually about helmets or politics. Then just look at the post-count in
Google Groups.

The bar is set awfully high for anyone to hope that this pitiful
little thread will reach pre-eminence.

Those who are impressed with this thread may be thinking of the "party
doll" thread, which ran a mere 678 posts in 2000, with 98 authors.

But the "published helmet research -- not a Troll" of 2004 easily
topped that minor flame-fest with 1788 posts from only 78 authors.

And the "Helmet Poll: First Hand Experience" thread in 2006 provoked
5,571 posts from 169 authors.

This thread has fewer than a thousand posts so far from only 41
authors, so it looks like a few enthusiasts desperately trying to
achieve a high post count through minor (if not negligible)
advantages.

:-)

Cheers,

Carl Fogel

wrote:


My guess is that most riders just use a pressure that they like,
without much continuing personal testing and without much reference to
any test results.

Most? Probably. However, there are certainly racers who do think about these
things and they test to find the right inflation pressure for a set of
circumstances.

I wrote:
wrote:


My guess is that most riders just use a pressure that they like,
without much continuing personal testing and without much reference
to any test results.

Most? Probably. However, there are certainly racers who do think
about these things and they test to find the right inflation pressure
for a set of circumstances.

BTW, I have a rule of thumb for tire inflation but I was waiting to see if
Tim would answer your question since you asked him directly.

On Feb 19, 5:53*pm, "Robert Chung"
wrote:
wrote:
My guess is that most riders just use a pressure that they like,
without much continuing personal testing and without much reference to
any test results.

Most? Probably. However, there are certainly racers who do think about these
things and they test to find the right inflation pressure for a set of
circumstances.

.... and it's been proven that they win far more road races because of
their precise tire pressures.

Was that the forgotten end of your paragraph?

If not, why not? Because surely, such improvements can't be
negligible!

- Frank Krygowski

On Feb 19, 3:04*pm, A Muzi wrote:


Tour of California Stage Four Merced to Clovis 115 miles and the end
looked justthisdarnedclose:http://asp.usatoday.com/_common/_scr...px?width=490&h...

http://tinyurl.com/bek7g8

What's the percent elapsed time difference between victory and 'else'?
(115 miles over a tire width or two)

Could you imagine (for example) a tire inflation difference that great,
aside from the tires themselves?
Could you agree that a relatively niggling minor difference (be it
equipment, mood, aerodynamics, food, drugs) between two highly skilled
riders could make that difference?

"My team really put me in a perfect position,” said Cavendish. “Mark
Renshaw (Team Columbia-Highroad) helped me; it was the first time we
got the lead-out right."

Oddly, Cavendish talked about team tactics, about being set up right,
about the lead-out for the final sprint. Somehow, he forgot to
mention his tire pressure!

- Frank Krygowski