For a while there the Zipp people were actually telling people to use the 4000S 23mm tire.

I imagine these are aimed squarely at that tire. I hope so anyway!

Notice the sidewall pattern!

---

---

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

I'm ready with the Crr values to post...with the exception of just one of the production models, which due to a mix-up in the prototypes sent to me, happened to not have been tested. That will be remedied shortly (within the next week) and then the full Crr data set will be revealed.

At this point, let's just say that both the Course and Speed models compare favorably to the "benchmark" in regards to rolling resistance ;-)

---

http://bikeblather.blogspot.com/

I'd be interested to hear any insight between the Course and the Speed models. I do like my GP4000S though!

The Speed looks to be Vittoria Diamante based with the 220tpi nylon casing... with no protection belt. Good for low Crr, not so good for punctures. Even the Diamante *with* an extra layer was pretty poor for that.

Might be pretty decent for TTs if the aero is good. Unfortunately no size smaller than 23...

Sine it appears the 4000S II has quality issues (multiple reports of failure), I have started searching for a comparable replacement, since the 4000s original version is hard to come by now.

That was my concern as well...but after putting quite a bit of miles on each model, I have to say that even the Speed models appear fairly durable...more so than my experiences with the Diamantes and other tires based on that casing. The compound feels different and more cut resistant, and the amount on the sidewalls seems slightly thicker as well, which could also possibly improve cut resistance.

---

http://bikeblather.blogspot.com/

I also like the price that you can get the GP4000s at. Doubt the Zipp tires would be anywhere close (if they are priced like the older model with zero discounting...).

Makes me think that it might be faster to roll a brand new set of GP4000s for your A race every year than use try and get your monies worth out of the Zipps at double the price by using them in multiple A races.

Ugh... there goes my interest.

---

The point is, ladies and gentleman, that speed, for lack of a better word, is good. Speed is right, Speed works. Speed clarifies, cuts through, and captures the essence of the evolutionary spirit.

MSRP is $65. I'm really cheap and I don't think that's bad at all. It sort of amazes that you think that is a lot of money in the grand scheme of things, especially on ST... for a race specific item.

The market for these tires (if they have leading Crr and aero numbers) will be people who want the fastest tire they can get.

Never said it is a lot of money. That being said, I have bought some GP4000s tire for $35. THe math doesn't work perfect but the Zipps are almost twice as expensive. For someone that wants to roll on fresh rubber for 2 races a year it makes a little difference in the pocketbook.

Also, lets wait for the numbers to come out to see if double the price is justified.

As a tangent, would I be incorrect in saying that many tire manufacturers skimp on the sidewalls in an effort to keep tire weight down? Thicker sidewall tread shouldn't really impact crr, correct?

Absolutely it would.

---

---

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

Makes sense now that I think about it: the entire tire deforms not just the point of contact.

sidewall is a pretty good place to go minimal too, since you don't often puncture it.

make sure the frame doesn't rub though!

---

---

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

I don't roll tubulars, but the Zipp site graphics makes it appear like their new SLSpeed has a latex tube. If the tread/casing offer decent durability this should be good news on Crr for anyone using tubulars...

We need the data first before we can make any assumptions at all.

---

If you are sure you will fail, or convinced you will succeed, you are probably right.....

It's funny you should ask that...when I was sent the final production candidates to test, there was an odd result with the 23C version of the Speed model actually rolling slightly faster than the 25C. After a bit of digging and comparing numbering on the tires, we realized that I had happened to be sent a different proto version of the 25C with slightly thicker rubber on the sidewalls. Now, this difference is something that one couldn't even perceive just looking at the tires and holding them in your hand.

Anyway, that was the result that is holding up the release of the Crr data. I have a 25C Speed coming to me as we speak.

So yes, sidewall material DOES matter in regards to Crr (along with tread thickness, rubber compounds, width, and puncture belts)

---

http://bikeblather.blogspot.com/

>We need the data first before we can make any assumptions at all.

Since when?

I think by definition, an assumption is made ahead of having all the answers.

My assumption here is based on following Al Morrison's years of tire testing results. At or near the top of his list were two Vittoria tubulars with latex inner tubes. Now Al also found that how the tubulars were glued made a big difference in Crr so with tubulars there will always be the potential for more variability based on installation.

I don't have a dog in the fight as I only run clinchers.

Can't wait to see your results. How about protection from punctures? Thoughts on that?

Full Crr results were posted yesterday:

http://bikeblather.blogspot.com/...peed-course-and.html

---

http://bikeblather.blogspot.com/

Tom,

Thanks for all the work you've done on this. Wow. just WOW!

By chance, do you have a Crr for the Vittoria EVO CX tubular?

Thanks,
FaS

Thanks. No data on that, but I'd expect it to roll comparable to similarly constructed tires.

---

http://bikeblather.blogspot.com/

The old AFM tables have that, and yes, basically same as the clinchers

---

---

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