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Tire selection for Zipp 303 CC

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styrrell

Apr 30, 12 7:47

Post #26 of 54 (1246 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
Do you agree that volume does? Frankly most of the time I understand what you are getting at when you want to split hairs, but on this point I don't.

Virtually everyone in the bike world, and I think this includes you, agrees that for a bigger diameter tire you optimally use less pressure. This holds true if its all tire making up the diameter ie tubulars, or if its a clincher. With a clincher it doesn't really seem to matter whether or not the increased diameter is due to more tire or more rim.

Beyond that you lost me in the point you're trying to make, I've read Sheldon's article, I get what he is saying, but he doesn't mention verticality of a side wall, and thats nonsensical anyways, a fat motorcycle tire has no more verticality than a skinny track tire. They both have curved sidewall, which mathmatically speaking have a singular dimensionless point of verticality.

All Sheldon's artical explains is how a tire made from fabric, which has zero compression, supports the riders weight, and parathetically why bigger tire need less pressure.

I did like the irony in your post where you took offense to being labelled an internet schoolmarn, and then pointed out a spelling mistake.
Styrrell

Carl Spackler

Apr 30, 12 8:08

Post #27 of 54 (1236 views)
 Re: Tire selection for Zipp 303 CC [Rappstar] [In reply to] Quote | Reply
On the 808 FC, run the Conti over a Tangente in a 23?

__________________________________________________

Tom A.

Apr 30, 12 8:30

Post #28 of 54 (1230 views)
 Re: Tire selection for Zipp 303 CC [styrrell] [In reply to] Quote | Reply
styrrell wrote:
Do you agree that volume does?

Absolutely not. Take a given clincher tire and rim setup and imagine that after the tire is installed it's somehow possible to "fill in" the rim bed area (such that the deflection of the tire casing is unaffected). At the same pressure, the tension in the casing cords is the same as for the "unfilled" case (since it is determined by the tire geometry and the pressure), and the "optimal" pressure is unchanged even though the total air volume inside the tire is dramatically different.

It's not about the internal air volume...it's about the "effective tire radius" of the particular tire/rim setup.

So, we're in agreement that it doesn't really matter whether the "effective tire radius" is gotten with a wider tire on a given rim, or with a wider rim with a given tire. But, to say that the lower "optimal" pressure is a direct result of the larger air volume is demonstrating a complete misunderstanding of cause and effect in the situation.

http://bikeblather.blogspot.com/

(This post was edited by Tom A. on Apr 30, 12 8:34)

jackmott

Apr 30, 12 8:33

Post #29 of 54 (1224 views)
 Re: Tire selection for Zipp 303 CC [Carl Spackler] [In reply to] Quote | Reply
Carl Spackler wrote:
On the 808 FC, run the Conti over a Tangente in a 23?

I know, is Zipp about to come out with a new tire?

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
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styrrell

Apr 30, 12 8:50

Post #30 of 54 (1213 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
Ok I at least see what you are saying, but I'm still not sure what you are saying is true. For one a tire isn't a rigid structure, it expands with higher pressure, and air is compressible. If all that mattered was cord tension then why not come up with permanent closed cell foam filling with of the proper size to give the ideal cord tension and be done with pumps and flats.

On a pneumatic system as compression goes up the volume and pressure change and thats where a lot of the suspension comes in, much like a proper suspension fork you don't want linear response you want a hard hit to offer more resistance. Granted the effect of a tire impacting road bumps is much smaller than a properly designed air sprung fork, but there is a reason that mtb shocks don't go for a tiny air chamber vs larger ones.
Styrrell

Tom A.

Apr 30, 12 8:57

Post #31 of 54 (1211 views)
 Re: Tire selection for Zipp 303 CC [styrrell] [In reply to] Quote | Reply
styrrell wrote:
Ok I at least see what you are saying, but I'm still not sure what you are saying is true. For one a tire isn't a rigid structure, it expands with higher pressure, and air is compressible. If all that mattered was cord tension then why not come up with permanent closed cell foam filling with of the proper size to give the ideal cord tension and be done with pumps and flats.

On a pneumatic system as compression goes up the volume and pressure change and thats where a lot of the suspension comes in, much like a proper suspension fork you don't want linear response you want a hard hit to offer more resistance. Granted the effect of a tire impacting road bumps is much smaller than a properly designed air sprung fork, but there is a reason that mtb shocks don't go for a tiny air chamber vs larger ones.

The reason a pneumatic bicycle tire is such a great invention is the fact that the "air spring" of the tire has basically a linear response (no appreciable pressure increase occurs due to the VERY small compressed volume vs. the total volume - even with the "filled in" example I gave above), along with the fact that the air spring has little to no damping losses. Both of those features lead to low Crr as compared to solid, or even closed cell foam tires.

Besides the fact that both are sprung by air, the design and function of a pneumatic tire and an air shock aren't really all that similar...

http://bikeblather.blogspot.com/

(This post was edited by Tom A. on Apr 30, 12 8:58)

mopdahl

Apr 30, 12 10:09

Post #32 of 54 (1175 views)
 Re: Tire selection for Zipp 303 CC [SharkFM] [In reply to] Quote | Reply
Good and IMHO accurate thread on the differences between Pave's & Contis. FWIW my experience has pretty much been the same: Contis last longer (about 2x as long), are less prone to cuts/punctures (especially in the 2nd half of their life). Pave's simply feel better.

Tom A. is (seemingly) all about the science of the bike, after all he rides an S5 which as Cervelo will certainly tell you is the "fastest" road bike on the market. That riding it is akin to straddling a splintery 2x4 doesn't matter to some; to me the feel of a bike on the road is the most important thing. I'm sure that my Parlee Z5SLi is slower in the wind tunnel. However I'm also sure that whatever real world "losses" are incurred in terms of aerodynamics b/c I choose to ride a non-aero bike with Pave's instead of Conti 4000s are more than recouped by the extra joyous hours that I spend riding my choice of setups.
____________
“There are two novels that can change a bookish fourteen-year old’s life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs.” John Rogers

jackmott

Apr 30, 12 10:22

Post #33 of 54 (1163 views)
 Re: Tire selection for Zipp 303 CC [mopdahl] [In reply to] Quote | Reply
ride your choice of setups when training, ride the fast stuff when racing =)

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
The newest tri shop in Austin - ATC 360
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mopdahl

Apr 30, 12 10:33

Post #34 of 54 (1157 views)
 Re: Tire selection for Zipp 303 CC [jackmott] [In reply to] Quote | Reply
About the only race I'd consider riding Conti's vs Pave's would be a time trial with limited cornering, or a road race with limited cornering. Certainly not crits or any race where confidence in corners is key.

FWIW I'd rather train with Conti's for their durability & race on Pave's, but riding in the SoCal moutains on Pave's gives me a warm & fuzzy that is worth the risk of an occasional flat (and FWIW my experience has been that the Pave's are fine up until about 75% of their life is gone).
____________
“There are two novels that can change a bookish fourteen-year old’s life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs.” John Rogers

jackmott

Apr 30, 12 10:37

Post #35 of 54 (1150 views)
 Re: Tire selection for Zipp 303 CC [mopdahl] [In reply to] Quote | Reply
and now you can't do a crit well on continental tires OR aero road frames.

but I see both things happen, sometimes on the same bike, all the time!

=)

mopdahl wrote:
About the only race I'd consider riding Conti's vs Pave's would be a time trial with limited cornering, or a road race with limited cornering. Certainly not crits or any race where confidence in corners is key.

FWIW I'd rather train with Conti's for their durability & race on Pave's, but riding in the SoCal moutains on Pave's gives me a warm & fuzzy that is worth the risk of an occasional flat (and FWIW my experience has been that the Pave's are fine up until about 75% of their life is gone).

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

nslckevin

Apr 30, 12 11:27

Post #36 of 54 (1123 views)
 Re: Tire selection for Zipp 303 CC [SharkFM] [In reply to] Quote | Reply
SharkFM wrote:
Let's go back to mopdahl's observations. Bigger rider on more volume and a wider rim makes sense as does the stickier Vittoria tire. But that comes at a price of wear and possibly more puncture flats.

After 25 years racing on tubulars I decided to go with the 404 FC clinchers this year. After consulting Al Morrison I went with the Vittoria clincher with the caveat that "they can be somewhat fragile". I figured that I've had great luck with Vittoria tubulars over the years and they can't be less durable than tubulars, right?

Not so much.

I made it through a lap and a half of Copperopolis where I broke a crank arm. ~40 miles
I rode the 45+, 35+ and P/1/2 Santa Cruz Crit ~75 miles
I rode the 45+ road race at Sea Otter where I flatted the front on the neutral rollout and then flatted the rear with about 10 miles to. ~65 miles total
I rode the Wente Brute road race on Saturday and flatted the rear about 3/4 of the way through the first 15 mile lap.

Those tires have less than 200 miles on them!

On Sunday I ordered a set of Conti 4000's.

I've had more flats this year already than in the previous two years of racing.

I love my Vittoria tires and I'm not a huge Conti fan, but you've got to finish to win.
Kevin

jackmott

Apr 30, 12 11:35

Post #37 of 54 (1121 views)
 Re: Tire selection for Zipp 303 CC [nslckevin] [In reply to] Quote | Reply
did you determine the cause of each flat?

clinchers allow for many ways to flat other than punctures. (rim tape askew, installation of tube errors, etc)

Memorial day sale at ATC and Meet Pro Triathlete Matty Reed - Sat May 25 - Captex!
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

styrrell

Apr 30, 12 13:30

Post #38 of 54 (1096 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
Besides the fact that both are sprung by air,

Yes by all means lets ignore the most important aspect of pneumatic suspension. 2 questions, if cord tension is all that matters why given the same rim and width tire don't you have to use dramatically different pressures with an 80 TPI vs a 320 TPI, obviously the cord tension varies by a factor 4, yet we don't use very much pressure difference if any.

2nd and more importantly you must realize that in real life riding on real road with rock and holes and curbs, etc having more volume with a air sprung tire give beeter performance or are all the pros wrong about tire choice at the cobbled classics?
Styrrell

nslckevin

Apr 30, 12 14:06

Post #39 of 54 (1075 views)
 Re: Tire selection for Zipp 303 CC [jackmott] [In reply to] Quote | Reply
jackmott wrote:
did you determine the cause of each flat?

clinchers allow for many ways to flat other than punctures. (rim tape askew, installation of tube errors, etc)

I did not find a thorn or piece of glass in the front flat at Sea Otter, but I had done four races on that wheel with no problem so I would assume there were no tape/mounting issues.

The rear flat was a thorn.

This weekends flat is unknown. I didn't find anything in the tire. It wasn't a blow out, it's just a small puncture, but it's hard to find the holes on a latex tube because as soon as you get enough pressure to open up the hole a 5-6" section of the tube ballons out and lowers the pressure and you can't find the hole any more.

I guess it could be worse. If I was on tubulars, I'd already be out over \$300 in tires...
Kevin

Tom A.

Apr 30, 12 14:20

Post #40 of 54 (1066 views)
 Re: Tire selection for Zipp 303 CC [styrrell] [In reply to] Quote | Reply
styrrell wrote:
Besides the fact that both are sprung by air,

Yes by all means lets ignore the most important aspect of pneumatic suspension.

Who's ignoring it? The fact is that the pressure inside a bicycle tire does NOT increase appreciably due to compression in the contact patch. Do the math. Compare the change in internal volume for a bicycle tire from a typical large bump compression (or even from the unloaded to loaded condition) with the change in internal volume of an air shock through it's stroke travel. It's pretty easy to see that in one case there is basically a linear spring rate, and in the other there isn't.

styrrell wrote:
2 questions, if cord tension is all that matters why given the same rim and width tire don't you have to use dramatically different pressures with an 80 TPI vs a 320 TPI, obviously the cord tension varies by a factor 4, yet we don't use very much pressure difference if any.

You accuse me of being overly picky and then you hang your hat on this? Obviously, I was referring to the tension radially at the bead per unit length of tire, not the tension in the individual fibers.

styrrell wrote:
2nd and more importantly you must realize that in real life riding on real road with rock and holes and curbs, etc having more volume with a air sprung tire give beeter performance or are all the pros wrong about tire choice at the cobbled classics?

It's not the total air volume of the tire, but the allowable bump compliance that matters in that case. There's a difference.

If it was all about the air volume, then why wouldn't they just run 23C tires with rims that have huge empty cavities in the rim bed? That's more total air volume, right?

http://bikeblather.blogspot.com/

Tom A.

Apr 30, 12 14:26

Post #41 of 54 (1059 views)
 Re: Tire selection for Zipp 303 CC [nslckevin] [In reply to] Quote | Reply
nslckevin wrote:

This weekends flat is unknown. I didn't find anything in the tire. It wasn't a blow out, it's just a small puncture, but it's hard to find the holes on a latex tube because as soon as you get enough pressure to open up the hole a 5-6" section of the tube ballons out and lowers the pressure and you can't find the hole any more.

Sometimes the easiest way to find the small holes in a latex tube is to put just enough air in that it doesn't "balloon" and then go around the tube holding a section at a time under water and stretching the tube sideways and then looking for bubbles.

Your first and third "flats" sound suspiciously like rim tape or installation/removal problems. If you ever had the tires/tubes off the rims then you have to be VERY careful with using a tire iron with the latex tubes. If after breaking the bead over the rim sidewall you try to run the lever around the rim to get more of the bead off, it can be VERY easy for the edge of the iron to "grab" a section of tube and cause a small tear. It's gotten to the point where I put a bit of talc on the end of the tire iron when I go to remove a latex tubed tire....

http://bikeblather.blogspot.com/

styrrell

Apr 30, 12 14:31

Post #42 of 54 (1051 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
"Besides the fact"
"Who's ignoring it?"

Er?

"Obviously, I was referring to , not the tension in the individual fibers.

First it was sidewall verticality, then cord tension and now the tension radially at the bead per unit length of tire. Trust me your neither clear nor obvious.

It's not the total air volume of the tire, but the allowable bump compliance that matters in that case. There's a difference.

Yes and the difference is bigger tires or bigger rim/tires systems give more compliance when run at low pressure, and better performance than smaller tires on rougher roads. Which matters, Which is why people like them.
Styrrell

Tom A.

Apr 30, 12 14:55

Post #43 of 54 (1042 views)
 Re: Tire selection for Zipp 303 CC [styrrell] [In reply to] Quote | Reply
styrrell wrote:
"Besides the fact"
"Who's ignoring it?"

Er?

A pneumatic tire and an air shock have one thing in common: air is used as the "spring element". How those springs behave under use is completely different. YOU are the one ignoring that fact.

styrrell wrote:
First it was sidewall verticality...

Can you illustrate for me the angle of the casing at the bead relative to vertical for a 23C tire on a 19mm rim vs. a 24mm wide rim?

As I said earlier, pointing to that was a bit "simplistic" on my part since it's not really the true cause of the higher tire stiffness for a given tire on a wide vs. narrow rim at the same pressure. But, the fact that you won't let that one "go" is pretty telling...

styrrell wrote:
...Trust me your neither clear nor obvious.

...only to someone who appears to not want to think critically about the mechanisms involved in a pnuematic tire.

styrrell wrote:

Yes and the difference is bigger tires or bigger rim/tires systems give more compliance when run at low pressure, and better performance than smaller tires on rougher roads. Which matters, Which is why people like them.

Sigh...still having problems separating out air volume, tire size, and pressures I see. Oh well, I can lead a horse to water...

Why haven't you answered my question about regular-sized tires with extra volume in the rims? If it's all about total air volume, why doesn't that work?

http://bikeblather.blogspot.com/

nslckevin

Apr 30, 12 15:06

Post #44 of 54 (1033 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
Tom A wrote:
Your first and third "flats" sound suspiciously like rim tape or installation/removal problems.

The first flat seems an unlikely candidate. That tube was installed by hand and had been in place for several weeks and a number of races.

This weekends flat is a higher probability of being user error since I had just installed it on Thursday and had not been used yet other than a short warm up.

Though I do use the tire iron like you describe to remove tires, none of the flatted tubes had ever been removed or seen a tire iron. I haven't reused any of my flat latex tubes. Which BTW, were Vittoria for the first two and Vredistein for the replacements. No particular logic to the tube choices, just what was available were I got them.

Thanks for the advice as to the fragility of the latex tubes. I hadn't thought of the tire iron causing problems.
Kevin

Tom A.

Apr 30, 12 15:11

Post #45 of 54 (1030 views)
 Re: Tire selection for Zipp 303 CC [nslckevin] [In reply to] Quote | Reply
nslckevin wrote:
Tom A wrote:
Your first and third "flats" sound suspiciously like rim tape or installation/removal problems.

The first flat seems an unlikely candidate. That tube was installed by hand and had been in place for several weeks and a number of races.

Actually...one of the reasons that a pristine rim tape and rim bed setup is required when running latex tubes is the fact that they will "find" any small gap to extrude through and eventually fail...even after having been in place for a while. I'd see if you can find the location of the hole and then see if it matches up with any unwanted features inside the rim bed.

nslckevin wrote:
Thanks for the advice as to the fragility of the latex tubes. I hadn't thought of the tire iron causing problems.

De nada...I've put so many holes in perfectly good latex tubes just removing them that I've learned that lesson well enough :-/

http://bikeblather.blogspot.com/

Jamaican

Apr 30, 12 15:12

Post #46 of 54 (1029 views)
 Re: Tire selection for Zipp 303 CC [In reply to] Quote | Reply
Dis thread wuz already got rolled since da second posst. Y'all be trollin brah.

I'm sorry I offended you when I called you stupid. I honestly thought you knew.

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Tom A.

Apr 30, 12 15:22

Post #47 of 54 (1015 views)
 Re: Tire selection for Zipp 303 CC [mopdahl] [In reply to] Quote | Reply
mopdahl wrote:
Tom A. is (seemingly) all about the science of the bike...

Actually, no...but it's nice when folks don't spread misunderstandings about bike technology. That just leads to further "myth and lore" in the cycling world...

mopdahl wrote:
... after all he rides an S5 which as Cervelo will certainly tell you is the "fastest" road bike on the market. That riding it is akin to straddling a splintery 2x4 doesn't matter to some...

Ummm...not even close.

http://bikeblather.blogspot.com/

styrrell

Apr 30, 12 18:59

Post #48 of 54 (961 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply

Why haven't you answered my question about regular-sized tires with extra volume in the rims? If it's all about total air volume, why doesn't that work?

Maybe because their is no evidence or data that more air volume doesn't help feel other than you saying so. And no evidence that a rim constructed with extra volume doesn't feel better other than you say it doesn't. Seriously again we are at the point where you can't produce evidence yet we must believe its so. I'll bow out now, much like when I stated that Zipp really doesn't produce a 303 Firecrest, and all pro bikes weigh the limit as evidence by the links to 3-4 overweight bikes.

Come up with some data seeing as you seem to know that the theoretical rim doesn't make a difference then I'll debate the point. (incidentally you might ewant to look at the "begs the question" definition now.)
Styrrell

mopdahl

Apr 30, 12 19:39

Post #49 of 54 (951 views)
 Re: Tire selection for Zipp 303 CC [Tom A.] [In reply to] Quote | Reply
"That riding it is akin to straddling a splintery 2x4 doesn't matter to some..."
Ummm...not even close.

Ok, you are right. Its only like riding a warped 2x4, not one that also has splinters.

Seriously dude, its one of the deadest feeling bikes I've ever been on....similar to circa 2000 era Trek OCLVs.
____________
“There are two novels that can change a bookish fourteen-year old’s life: The Lord of the Rings and Atlas Shrugged. One is a childish fantasy that often engenders a lifelong obsession with its unbelievable heroes, leading to an emotionally stunted, socially crippled adulthood, unable to deal with the real world. The other, of course, involves orcs.” John Rogers

Tom A.

Apr 30, 12 19:47

Post #50 of 54 (947 views)
 Re: Tire selection for Zipp 303 CC [styrrell] [In reply to] Quote | Reply
styrrell wrote:

Why haven't you answered my question about regular-sized tires with extra volume in the rims? If it's all about total air volume, why doesn't that work?

Maybe because their is no evidence or data that more air volume doesn't help feel other than you saying so. And no evidence that a rim constructed with extra volume doesn't feel better other than you say it doesn't. Seriously again we are at the point where you can't produce evidence yet we must believe its so.

It's not because I say so, it's because it's simple physics. Do the math. I told you what to look at.

http://bikeblather.blogspot.com/

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