700/23 vs 700/25 tires ?

On Wed, 11 Feb 2009 23:58:59 GMT, John Forrest Tomlinson
wrote:

On Wed, 11 Feb 2009 12:43:48 -0800 (PST), Frank Krygowski
wrote:

Do you coach riders to ignore that? Do you get into semantic
arguments with them?

You're a jackass BTW.

Dear John,

Ah, you do my heart good!

No one can hide his true nature for long.

Cheers,

Carl Fogel

On Thu, 12 Feb 2009 00:03:08 GMT, John Forrest Tomlinson
wrote:

On Wed, 11 Feb 2009 13:34:58 -0800, "Robert Chung"
wrote:

Um, Frank? Even after just reading that article, your memory played tricks
on you. This thread really isn't doing you any favors. That test did not
"[cast] serious doubt on the very concept of an aero water bottle." That
test was mostly about *placement of conventional water bottles* on the down
tube, on the seat tube, or behind the seat. In fact, the fastest bottle
tested was an aero water bottle, placed between the handlebars. It's kinda
worrisome that you remembered the test that shows the aero bottle to be the
fastest as a test that cast serious doubt on the very concept.

Dumbass.

You don't get it. The whole point of Frank (and Carl F and a few
other guys) is that if something is "fancy" or "expensive" or "trick"
it has to be a marketing scam and either doesn't work, performs worse
or will break. Preferably all three.

Get with the program.

Dear John,

Ah, you do my heart good!

No one can hide his true nature for long.

Cheers,

Carl Fogel

In article
,
Frank Krygowski wrote:

On Feb 11, 6:38*am, John Forrest Tomlinson
wrote:
On Tue, 10 Feb 2009 21:21:33 -0800 (PST), Frank Krygowski

wrote:
You tell me what percentage of road
races are won based on solo breakaways, for example. *

Nice of you to try to slip "solo" in there, but talking about
breakways of all types it's somewhere between 20 and 60%

And who usually wins the final sprint, John? Is it the guy barely out
front in the last quarter mile? Or is it one of the guys just behind,
in a draft, who whips around at the last couple seconds?

What would you tell a novice you were coaching? "Make sure you're in
the lead for the last quarter mile, because that way you're fighting
the wind by yourself, and your aero water bottle gives you a greater
drag reduction"?

Frank, this is a strange and straw-filled argument. Assuming you're not
just being tendentious here, when a small break does escape, there are
numerous factors working against it staying together, and riders have
different strengths. Those, taken together, dictate when a rider should
put their nose in the wind.

But the short answer? It happens all the time that the rider in the lead
for the last quarter-mile wins. Examples off the top of my head are
LeMond's first world championship and Svein Tuft's 2007 US Open victory.

The video of the closing laps of Tuft's win is like a little textbook of
bike racing:

http://www.steephill.tv/2007/us-open...s/finale-video.
html

Another short answer? If you're not the best sprinter in your break, you
had better pop from the break before the sprint.

--
Ryan Cousineau http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."

Ryan Cousineau wrote:
"Robert Chung" wrote:

Michael Press wrote:
"Robert Chung" wrote:

You're lucky I'm only slumming over here in rbt until Het Volk.

That's uncalled for.

You're right. I was caught up in the moment and got carried away. I
apologize for the collateral damage.

I dunno. Crazy, smack-talking Chung was even more fun than charting
Chung.

It now seems appropriate to post this webcomic:

http://xkcd.com/54/

Dumbass,

1. If they did POTM over here in rbt I would've nominated Press. I laughed
at that thing for a whole day.

2. The reason you don't often see that Chung is cuz most folks know enough
not to call me out and then show up for the knife fight carryin' a spoon.

On Wed, 11 Feb 2009 17:41:53 -0800, "Robert Chung"
wrote:

wrote:

But I'm wondering there's any easy way to calculate what the effect
would be, in theoretical seconds saved over the 2003 water bottles.

A general rule of thumb (which I usually call ROT for perhaps evident
reasons) that Andy Coggan uses is that 0.1 lbf = 0.5 sec/km = .005 m^2.
(That's a very abbreviated ROT: a longer version is "0.1 lbf measured at
wind tunnel speeds (50km/h) translates to about 0.5sec/km at the speeds that
make you competitive at TTs, i.e, around 40km/h, which is also the speed
change from a difference in CdA of .005 m^2.")

0.1 lbf is 45g, so a 100 g difference in wind tunnel measured drag force is
in the ballpark of .01 m^2 or 1 sec/km. Over a standard 40km TT, that's
huge.

BTW, because of the architecture of wind tunnels you can get slight
differences in measured drag from tunnel to tunnel. The relative rankings
appear to be robust, though.

Dear Robert,

Thanks!

I was wondering if there was some way to estimate the change, but had
no idea where to start looking.

So at 1 sec/km for a 100 gram drag reduction, the predicted time
savings would be roughly 40 seconds in a 40 km race (with the obvious
emphasis on this being just a rule of thumb).

Sorting Cobb's 2003 data and predictions for 225 watts and adding some
results to see how Cobb's predictions compare with Coggan's ~0.1 lbf
drag change = ~0.5 sec/km rule-of-thumb X 40 km . . .

time Coggan
drag 40 km secs lbs drag
lbs 225 w secs /km drag ROT
/40km /40km
* *
Profile bottle only 7.337 1:06:53 0 0 0 0
down tube bottle only 7.370 1:06:58 -5 -0.200 +0.033 -6.6
seat tube bottle only 7.433 1:07:09 -16 -0.400 +0.096 -19.2
base bike, no bottles 7.537 1:07:26 -33 -0.825 +0.200 -40.0
Hydropac w/40oz. only 7.556 1:07:29 -36 -0.900 +0.219 -43.8
Never Reach only 7.561 1:07:30 -37 -0.925 +0.224 -44.8
behind-seat high bottles 7.578 1:07:32 -39 -0.975 +0.241 -48.2
bottles on both tubes 7.598 1:07:36 -43 -1.075 +0.261 -52.2
behind-seat low bottles 7.658 1:07:45 -52 -1.300 +0.321 -64.2
http://www.slowtwitch.com/mainheadin...erbottles.html

That looks like pretty good correspondence, so Cobb and Coggan are
probably using very similar models and the 0.1 lbf drag = 0.5 sec/km
seems quite reasonable.

Thanks again for the explanation and that rule of thumb figure.

Cheers,

Carl Fogel

On Thu, 12 Feb 2009 01:42:58 GMT, Ryan Cousineau
wrote:

In article ,
"Robert Chung" wrote:

Michael Press wrote:
"Robert Chung" wrote:

You're lucky I'm only slumming over here in rbt until Het Volk.

That's uncalled for.

You're right. I was caught up in the moment and got carried away. I
apologize for the collateral damage.

I dunno. Crazy, smack-talking Chung was even more fun than charting
Chung.

It now seems appropriate to post this webcomic:

http://xkcd.com/54/

Dear Ryan,

Sigh . . . depending on the strip's current length, there goes another
hour or so.

Cheers,

Carl Fogel

On Feb 11, 4:12*pm, Michael Press wrote:
In article
,
*Frank Krygowski wrote:



On Feb 11, 4:32*am, Michael Press wrote:
In article
,
*Frank Krygowski wrote:
... if a person finds himself in that position
very often, his problem isn't aerodynamics; it's strategy.

If a tiny aero advantage ever does make the difference in winning a
road race, it can't happen more than once in a blue, blue moon.

You claim that most of the time most of the riders are sucking wheel.
However each spends time in the wind, and typically the same
amount of time. Anybody that tries to suck wheel all the time
is dealt with by the pack. When your time in the wind comes up
do you want your ears flapping like a pennant in a gale?

:-) Of course, like any serious rider, my ears wouldn't be flapping.
As you and others have noted, all serious riders tape their ears back
flat against their heads, for the obvious aero advantage!

The point I'm making about the peloton, which you, Robert and John are
steadfastly refusing to acknowledge, is that for the bulk of a road
race (not time trial), the wind-tunnel predicted magnitude of benefit
is simply not there. The 30 mph relative wind is not there, so the
small predicted benefit is much smaller. And if you really do work in
mathematics, Michael, surely you understand that there are factors
small enough that they don't matter - they're negligible.

(If you prefer, I could say there are factors small enough that the
probability of them mattering in any particular instance is
negligible. I wouldn't want you, like Robert, to ignore the overall
meaning and pounce on any phrase that allows the tiniest opportunity
to yell "gotcha.")

Or do
you want every aerodynamic advantage you can musters against
the competition?

NOBODY with sanity wants every aerodynamic advantage they can muster
over the competition - at least, not in road race or recreational
ride! If there is someone like that, you'll be able to spot him. He
really will have his ears taped back, all his body hair shaven, his
fingernails trimmed to the nub, and he'll be riding a very unusual set
of components, most of them made in the early 1980s. That's in
addition, of course, to being on a very unusual bike in the first
place.

One of the many questions unanswered by the "nothing is negligible"
crowd is why they consider those things negligible. One obvious
answer is that as I said, they look at a broad range of advantages and
disadvantages, not merely aero drag or weight as is being claimed
here. The other obvious answer is that some of the decisions are
driven by a form of fashion - "The other guys don't bother to tape
their STI cables back out of the wind, so I won't either."

A racer that throws away
potential advantages has already conceded the race.

I take that to mean "A racer that doesn't tape back his ears, shave
all body hair and file down his fingernails has already lost the
race."

That's what you meant, right? *You must use _every_ "potential
advantage"?

I meant what I said. Dismissing potential advantages is
a recipe for defeat; it means adopting a mental attitude
that does not promote winning.

When I did a little racing I never did tape my ears. How about you?
Seriously!

- Frank Krygowski

On Wed, 11 Feb 2009 19:32:36 -0700, wrote:

No one can hide his true nature for long.

I haven't been hiding anything.

On Thu, 12 Feb 2009 01:53:20 GMT, Ryan Cousineau
wrote:

In article ,
"Robert Chung" wrote:

Peter Cole wrote:
OK, perusing the Slowtwitch forum, I found an example of what you
describe:
http://www.biketechreview.com/tires/...sting_rev8.pdf

Either I'm missing something, or the data is junk, or it's obvious why
Bontrager doesn't publish this info.

Al Morrison (=AFM) does pretty careful work. I can dig up the exact protocol
if you're really interested. Note that Al includes a sd for the estimate--if
you have much experience with field testing you'll recognize that his
experimental precision is quite good. As I've said, others have verified
that when a significant difference between tires is observed in Al's data
it's preserved in outdoor field testing. Real road Crr depends not only on
the tire but also on the road surface so to get a good estimate of wattage
demands requires that you test on the real road. Guys are reporting that for
their own "typical" roads, the field tests show from 1.5x to 2x the Crr from
Al's table.

Those are single wheel estimates, btw, so if you switch both front and rear
from a poor Crr tire to one that's good, the wattage savings will increase.

Note also that the tests include some contrasts for type of tube, new vs.
used tires, and a few other things. .

Thanks for reminding me of the existence of this. And now it's kinda
killing me to see my beloved Kenda Kalientes languishing in the crap end
of the Crr pool.

And yes, I do care about my results enough to spend another $150 on
tires and latex tubes for the race bike, yes I do...

Dear Ryan,

Cheer up--sometimes $12 tires roll very well.

Here's Sam Whittingham talking about the complications of the tires
used on the Varna Diablo:

"In 1998, in Montreal at the PMG test track we had the luxury of
testing many things over the few weeks we were there including
different tire configurations. John Tetz showed us how to do some low
speed roll down tests that transferred quite well to the higher speeds
(60mph)."

"At that time we found the best rolling tire to be a continental tempo
track tubular at 175psi ($100) we still use this on the back of
Diablo. Last year when I went 81mph we tried some Vittoria track
tubulars ($125) because they pumped up to 240psi. We gave up on them
because they were as much as 1/4 inch out of round!"

"The tire that performed almost as well and has been my front tire for
7 years is a panaracer technova clincher at 135psi ($11.99) very
cheap! This is also one of the roundest tires I have ever found.
Obviously cost has nothing to do with performance!"

"We also tested the tufo tires. They seemed like the perfect solution.
They could take ridiculous amounts of pressure. Because they are
rolled in there construction rather than sewed they are the most round
and uniform tire I've ever seen. They also have sturdy side walls and
are reasonably inexpensive. Seems perfect right? One big flaw, slow as
molasses. I was as much as 4 mph slower on these tires even at
200psi."

"I spent a few days trying to top 96km/h in Montreal. I switched to
the panaracers and immediately went 101km/h several times. This was
shown in our rolldown test as well when I rolled nearly 50% further on
the cheap panaracers. Even on my road racing bike I could feel that
the tufo's were sluggish."

"I soon realized that you could easily guess a tire's rolling
resistance by the suppleness of the sidewall. The lighter and more
flexible the faster it rolls. Problem is, it doesn't give you much
room for scrubbing the fairing. So to go fast you need a tire with an
inherently fragile sidewall and pray you don't knick it. Hence, my
80mph blow-out It was one of my beloved panaracers that gave out on
me. Several factors caused this:"

"First: the tire was old. We also found older tires roll better.
probably because the sidewalls have broken down a little. We had
checked it before every run and it was still good but not great. I
could see some threads starting to fray, but nothing I considered
dangerous."

"Second: The pressure on the side said 125psi we were running them at
175psi. We had tested several the panaracers at over 200psi for
several days with no bulging or any deterioration. We ran at 175psi
all week and the tires were fine after every run. Slightly larger but
still round."

http://www.recumbent-bikes-truth-for...r-october-2003....

[I think that the 24" Panaracer Tecnova was 25 mm or even wider.]

Cheers,

Carl Fogel

On Thu, 12 Feb 2009 02:36:28 GMT, Ryan Cousineau
wrote:

But the short answer? It happens all the time that the rider in the lead
for the last quarter-mile wins. Examples off the top of my head are
LeMond's first world championship and Svein Tuft's 2007 US Open victory.

And on a little tiny scale, in one of the only two bike races I've
placed in in the last two years, I led a small group almost the entire
last K of the race and "won" the sprint for third. The field in this
event was very weak, but I did well in that group not by strength but
by timing and position on the road (the road was curved for part of
that and I stayed on the inside the whole way).

But this is getting off-topic so follow-ups are set to RBR if anyone
cares..