Thanks, Tom and Jack. Looks like I'll be getting new race tires next year. That (and a little weight loss and better helmet) may get me under :57 in a 40k.

Does that mean you have to change your username?

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/kj

http://kjmcawesome.tumblr.com/

Nope. 6ft and 178-180. Used to be 242. It's a reminder. Keeps me from going back. Now, in another year and a half, when I turn 60, I may change it to OldFatand Slow!

Tom,

I haven't found a picture of the tire on a complete wheel on which we can see cassette side... can you tell us or show us which way the grooves in the tire are supposed to be installed ?

Thanks ;-)

Grooves "pointing" towards direction of rotation when looking at the tread is how I understood it and mounted them.

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http://bikeblather.blogspot.com/

Tom, great info, thanks for all your work on this.

Now if only Zipp would make this in 650C for my wife...

So like an Attack in the recommended direction then ;-) . This is what I was wondering... thanks a lot !

So now the question is whether or not the Speed 25C aero penalty outweighs the crr advantage over the GP4000s 23c. I assume this is more relevant for the front tire.

What aero penalty? It is the same width as the 23c 4000S, and specifically designed to be aero rather than accidentally.

I bet it wins.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Well...if you're assuming that the Speed 25C is wider than the 23C GP4000S, you'd be wrong. If you read my blog post, you'd see that they both measured ~24.7-24.8mm wide when mounted on a Zipp Super 9 disc.

So, I'd expect the drag to be similar at near zero yaw. It remains to be seen what happens at higher yaw, but the Zipp tires aren't as parabola shaped as the Conti, so I wouldn't expect them to match at higher yaw angles. The aero data remains to be seen.

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http://bikeblather.blogspot.com/

Ha - I just read the blog post and headed back here to edit my post :) So the 25c Zipp is the same width as the 23c Conti. So much for standards.

The original tangente tires were pretty good in terms of aero. It would seem pretty stupid to change the tread pattern unless they at least stayed even with the previous version. Although I guess there could be something about the shape that they changed for other reasons. Still, for cases where I'm putting a ot of eggs into one basket like my Biennial IM race, I prefer the psychological comfort of knowing I have a pncture belt witht he Conti vs none with the Zipp Speed. Sounds like the Course is essentially the same as the Conti unless it has magic aero properties.

Mostly Conti's fault, that tire has always been big for 23.

I'm sure Zipp was like "What do we call this?...well 25s are hot now, lets go 25"

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Now that most rims are ~23mm wide, I suppose it is time to reevaluate the labeled dimensions. Not that the dimensions were ever reliable...

Seems that the tubular uses the Corsa casing, and the Speed uses the Diamante casing (without a kevlar belt, yikes!), but what does the Course use? The Rubino Pro is 150tpi now. And the Zaffiro is 60tpi. I don't think Vittoria does a 120tpi tire.

Damn good Crr for the Course, IMO.

So, I have been using 21C on my Zipp disc and 808. Is this data saying the best is the 27C now? Wonder is the 27 or 25 would be an issue to mount on my wheels?

.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

No...that says the 27C tubular has the lowest rolling resistance. But, it's 26.8mm freakin' wide. Aero (and surface area) still matters.

You didn't say if your wheels are tubular or clincher. What models are the 21C tires you are currently using? Is the 808 Firecrest? Need more info.

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http://bikeblather.blogspot.com/

this chart illustrates why I've gone from MOP to FOP despite getting older and slower. Damn you Zipp Tangente old model loosely glued to change a flat quicker!!!!

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Opps, cant read.

I have zipp tangente 21mm tires. These are clinchers. Do they not make 21mm anymore? I had assumed 21mm would be faster? And yep, these things are expensive. :o(

.

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Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

bump. any aero data coming out of InterBike?

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Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Dunno. They haven't said...and my trip this year had to be cancelled at the last minute (life) :-(

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http://bikeblather.blogspot.com/

This post deserves a like button :)

I have been running 23C GP4000s tires for years, but have had some fit issues on my new S5vwd. I am thinking of trying out the Zipps. Given the time of year (no racing), I am thinking of giving the course tires a go. They appear to only give up 1-2W to the speed tires and likely last a bit longer.

Anyone have thoughts on the Speed vs. Course for a daily tire? I am curious how the two ride.

Westernbikeworks has some pretty good deals on these now: 51 for the speed and 44 for the course.

I'm have the 23mm courses on my 404/808. I think they're very fast, but I haven't done any testing.

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Thoughts on being an Urban Triathlete