AFM Rev 9 testing or some other stuff he did? On Rev 9 I think the Crono tested was a 20mm.

yeah, the Crono looks good in tubular since the Triathlon version that Tom A. and rruff tested is butyl. Both of those guys also recommended the SL but why go with the SL when the Crono will do.

also, 21mm is a nice width. This is thinner than the 22mm quoted. How does it look mated up to your wheels. Which wheels do you have?

thx.

---

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.”

Its testing he did after rev 9. I think offically its called the crono II but most catalogues just call it the crono. The easiest way to tell for sure is the new one uses the replaceable red valve.

I have an original model zipp disc and a H3. mates up fine but I fill in the gap between the rim and tire with gasket compound.

---

Styrrell

think that affects Crr? I thought I read somewhere that it does. Either way, sounds fast.

Anyway, thanks for the info. I think I'll go Crono 20mm front and 22mm rear for the state TT and then Crono 22mm front and either CX or SL 23mm rear for Ironman

---

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.”

Liquid latex does NOT affect Crr - not sure what the gasket compound that styrrell is using ?? The newer and wider Crono 22 tested ~ 0.00226 IIRC and measured ~ 21 mm in width so really not much bigger than the older Crono 20 which did indeed measure ~ 20 mm. Vittoria now actually has a new version of the Crono that is even wider - 24 mm again IIRC. Haven't tested one of these. The spreadsheet is way out of date but there are some threads on BTR which have some more recent data. I haven't tested many tires lately due to some very gratifying but time consuming family contstraints.

don't matter, had sex!

---

---

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

Doesn't that make the new 22mm Crono the fastest road tubular out there? Sorry don't have my AFM 9 in front of me ;)

---

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.”

Yes. The Pista I tested was slightly better and the Conti SS 23 with latex tube is ~ the same as the Crono 22 (only tested one tire). The weight on several of the Crono 22's is ~ 185 grams compared to the advertised weight of 165 grams. I've heard from one source that the reliability is improved over the older Crono 20.

thanks. And congrats on the time-consuming family constraints!

---

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.”

Thanks - parenting a grandchild definitely consumes time. But it's very rewarding.

Hello Al! Do you recall testing the Conti Podium TT or any of their track tubulars (which you can use in TTs)?

Hi Ron, I haven't tested very many Conti tubulars. I did test a GP4000 which supposedly had the black chili compound but it was lightly glued but did not roll well - ~ 0.00384. IMO "proper gluing" would not have brought it up to TT racing consideration. Mounting it on the test wheel however did result in many blisters and colorful language - good thing the grandchild was not yet around the house. (:-)

Did the ST collective reach a consensus on this?

Why would you readjust your fit because the tire lowers the front. Your contact points on the bike are exactly the same. I suppose the "aero" might be different but are you sure that you've got it dialed in so closely that it needs to be changed.

---

Styrrell

all of the data points I've seen so far on the question of narrow tires on wide rims suggest narrow tires are faster on wide rims.

The zipp 303 *may* be an exception.

---

---

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

When you swap from a 23mm front tire to a 21mm front tire Your CG shifts backward by .34mm and down by .19mm so your weight distribution on the bike changes drastically.

It's just more of the typical triathlete princess-and-the-pea BS.

---

__________________________

I tweet!

 
Oh I dunno, I'm quite the princess and that seems like a pea to me =)

---

---

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

Backwards? Geometry says that CG will move forwards and down (counterclockwise).

That said, I can't tell the difference in ride height between tires. Tire grip and "feel"...yes.

---

The question of who is right and who is wrong has seemed to me always too small to be worth a moment's thought, while the question of what is right and what is wrong has seemed all-important.

-Albert J. Nock

I was being facetious.

But, if you want to get technical wit' it...

It all depends on the rider's position. Betweeen 180 and 270 degrees CCW from east (0) any further CCW rotation results in the vector projected length along the x-axis to shorten, whereas between 90 and 180 the projected length along the x-axis increases. For a rider in a very upright position I would imagine that the aforementioned tire swap would result in the CG moving forward a minuscule amount. For a rider in a great TT position with a flat back they may already be configured with the forward-most possible CG location such that any further CCW torso rotation (viewed from the non-drive side) results in the CG moving backward a minuscule amount.

BUT: This is definitely a case where 5mm is not 5mm. If by switching tires you lose 5mm of height on your front wheel this is not the same as losing 5mm height at your aerobar pads. If we assume for the sake of argument that the distance between your hips and your pads is 30cm and the distance between your seat and your wheel contact point is 1m, we can figure out some angles. Change in torso angle due to wheel radius change: tan(.005/1)=~.25degrees, whereas the change in torso angle due to pad height change: tan(.005/.3)=~.95degrees. This is more or less why you should give zero bothers about your front wheel radius/diameter as it pertains to your bike fit.


For the mathy folks: (caveat: small angle approximation)

---

__________________________

I tweet!

zack

well done

---

---

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

It all depends on the rider's position. Betweeen 180 and 270 degrees CCW from east (0) any further CCW rotation results in the vector projected length along the x-axis to shorten, whereas between 90 and 180 the projected length along the x-axis increases. For a rider in a very upright position I would imagine that the aforementioned tire swap would result in the CG moving forward a minuscule amount. For a rider in a great TT position with a flat back they may already be configured with the forward-most possible CG location such that any further CCW torso rotation (viewed from the non-drive side) results in the CG moving backward a minuscule amount.

BUT: This is definitely a case where 5mm is not 5mm. If by switching tires you lose 5mm of height on your front wheel this is not the same as losing 5mm height at your aerobar pads. If we assume for the sake of argument that the distance between your hips and your pads is 30cm and the distance between your seat and your wheel contact point is 1m, we can figure out some angles. Change in torso angle due to wheel radius change: tan(.005/1)=~.25degrees, whereas the change in torso angle due to pad height change: tan(.005/.3)=~.95degrees. This is more or less why you should give zero bothers about your front wheel radius/diameter as it pertains to your bike fit.

Or you coulda just said this ;-)


"Your contact points on the bike are exactly the same. "

---

Styrrell

thank you for the data. on top of the results there is an estimate suggesting 0.005 = .17mph gain. is this per tire or for both tires?

I did a TT with a friends powertap that had a maxis mounted. By far the worst time I have ever had on that course. We joked that maybe it was the tire and named the Maxis tires the "watt eaters". From the test data it looks like I was onto something.

I would love to see how this tire, the continental grand prix, fairs. Its a dumbed down version of the 4000

That estimate is for two tires.

I wouldn't call it dumbed down. It has a lower TPI casing, and a double PolyX breaker rather than Vectran. Still has Black Chili tread though, so it is probably a durable tire that isn't too slow.

The only tires I'd be inspired to buy and test would be promising race tires... or maybe everyday tires with a potential of being fast and cheap. If I want something a bit slower but cheaper and smooth riding, the Rubino Pros are hard to beat. PBK had those for $22 recently.