As fat as you can go is GREAT for mixed surface type riding, even with no knobbies. I was enlightened to that fact after taking a 3T Exploro shod with the WTB "road plus" slick tires for a jaunt on the MTB single-track at the Interbike Outdoor Demo this year (thanks SuperDave!). It's what inspired me to ditch using the 700C rims with 32C Gravel King tires on my "all-road" bike for some 26" wheels with the Rat Trap Pass tires I showed above. With the much lower pressures allowed, and the flexibility of the casing, the control and traction off-road are actually quite mind-boggling.

That said, I'm talking about what one wants to use on something that will most likely be taken off-pavement, including relatively rough single-track...something you're not going to do for tri (except Exterra, of course ;-)

Jan would disagree (based on his somewhat crude tunnel testing), but there IS an aero hit to going too wide for that application. I would defer to Josh's "105% width" rule of thumb that he developed when he was at Zipp (where for best aerodynamics, the widest part of the rim shouldn't be less than 105% of the mounted tire width - or, in other words, the tire shouldn't be greater than 95% of the widest part of the rim). There just isn't enough Crr to be gained from running wider tires for the typical smooth (relatively speaking) surfaces of tri courses.

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http://bikeblather.blogspot.com/

"I lose one watt using a GP4000S2"

well, this is where i need tom anhalt's help. if we take a turbo cotton as an example, it's 2 watts. and if that's per tire, then it's 4 watts. and if it's at 18mph, is that your average? your average is 24mph, does the power numbers scale? do they scale in a linear fashion? i don't know.

i'm not trying to talk you out of your tires. just, since you brought up the turbo cotton, is it 1 watt or 5 watts? i think that's to be determined, and then we ask ourselves how many watts it needs to be before we start to rethink our equipment choices.

i have no skin in the game. my deal with specialized is... nothing. my deal with schwalbe, michelin, hutchinson, vittoria is... nothing. i have nothing to gain by your changing to another tire. bless your heart, ride that tire.

i'm just questioning the absolute hegemony conti has over this market. whether it's warranted i'm not questioning conti, or the tire. great company! great tires!

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Dan Empfield
aka Slowman

Also keep in mind that when the GP4000 II came out, ST held their collective breath about the beloved original being ruined. Once it was confirmed there was no apparent differences, "we" all let out a sign of relief and kept on buying them.

I personally prefer the feel of the Specialized compound and ride the S-Works Turbo (not cotton) on my road bike. The $80 price-point of the Turbo Cottons is just too high when you look at the other offerings that are out there.

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/kj

http://kjmcawesome.tumblr.com/

While I've got you here (and I may have mentioned this before) what do you think about using ballistics gel as the weight load to simulate the impedance losses? Heck, now I know I've asked you before. Maybe I just need to build my own setup :)

You're assuming 70% is high, based on how it stacks up from a variety of metrics it could easily be higher than 70%. The others tires you mentioned can't compare on price in combination with all the metrics discussed in this thread. You should be asking why it's not 100%.

Let's say it's the whole 4w.

Applying Flo's rule of thumb, I save 12 seconds or less over an Olympic with the better tyres. But I have spend more on consumables while I'm saving for a wedding, which I have to change on and off for race day (I tend to put new 4002s on and then leave them on for training), at the risk of increased punctures which would cost me several minutes and considerably decrease my enjoyment of the race.

I started tri two years ago knowing nothing. I did some research, Slowtwitch said they were the best allrounders, and I've seen nothing to convince me there's a better choice for me.

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'It never gets easier, you just get crazier.'

"The others tires you mentioned can't compare on price in combination with all the metrics discussed in this thread."

if you're saying there's not a $35 tire that can compare to the 4000S II, you might be right (altho i found a michelin power competition online today for the mid-30s, but that's rare).

if i'm willing to spend a bit more on a tire i believe i can find tires that are certainly the equal, and perhaps the better, of that tire.

maybe i'm an elitist because i'm willing to spend an extra $15 or $20 per tire to get 4 or 5 watts (and with the same puncture resistance). but when i look at what many of the rest of us here are willing to spend to get 5 watts, it seems to me that is a pretty efficient spend.

again, nothing against that tire! but i don't think the landscape is the same today as it was when that tire first came out.

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Dan Empfield
aka Slowman

Train on the GP4000s II: Great mix of durability, grip, flat resistance, low Crr, and wide availability at reasonable prices. I run 23c, but 25 and 28 are readily available as well.

Race on Supersonics: Super-fast tire that corners well from a brand I've had good experience with.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

His testing has been invaluable but it's a lot to ask of one person to keep up with that year after year. And companies have little incentive to do an unbiased comparison. So I don't really know what the solution is.

Conti can continue being a great tire, but if other brands catch up or surpass them, it should be pointed out. Watts saved is a relative scale in this discussion. (Not saying it happened) but if everyone else improves and you stay the same, well now that's watts-lost.

In Flo's wind tunnel study of their new wheels the 4000sII was faster than the Turbo Cotton and Schwalbe One at 21 mph, a pretty attainable speed. That advantage will only grow as the speed increases. I stocked up on the 4000sII when Ribble had them for $25 each which is pretty unbeatable from a price/performance viewpoint. If Specialized would add the Turbo Cotton to their two for one sale they have occasionally I would love to try it but at $80 it's just too much of a price difference.

Unfortunately there is no aero data on the Michelin Power Competition which is available for reasonable prices around $35 as you have noted but I will be trying that tire when I run out of my current stock of GP4000.

I have the GP4K2 because they are consistently one of the top options. My perception is that the top few my be pretty close, and the social marketing of the GP4K2 is very strong. If I had high confidence that another tire was materially better, I would switch in a minute. Tires are so cheap, relatively, that I do not consider it a cost issue.

How are there something like 100 posts and not one that specifically calls out the Vittoria Corsa Speed (Open TLR).

I live in Los Angeles with a massive crit racing community, that I personally feel never research their products, they simply buy based on friendly reviews and whats in stock. With that said and them not knowing the data behind the tire, this is by far and away the one product that everyone LOVES. I mean, just gaga over. Take that into consideration... You have data that says this is the fastest tire available and then a massive group of road racers that say this is the best tire they've ever used.

And FWIW... I really pushed them to give me stats on how long they've ridden the tires. Not one said anything bad about cuts/wear. Most were getting upwards of 1,000 miles and they were still happy.

"His testing has been invaluable but it's a lot to ask of one person to keep up with that year after year."

that's not what i mean. the testing is routinely done, and it's current. i just don't know all the answers to the questions i have the way tom would. tom, josh poertner, some of these folks are just way ahead of me, and i'd rely on them for guidance. but the data is there.

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Dan Empfield
aka Slowman

"How are there something like 100 posts and not one that specifically calls out the Vittoria Corsa Speed"

yup. slays everything. the only knock on that tire (notwithstanding the experience of your cohort) is tread punctures. it's got a nice sturdy sidewall, which i think is pretty amazing considering the rolling resistance (or lack of it). but it does test a little thin on tread punctures.

i think your point demonstrates my point in starting this thread.

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Dan Empfield
aka Slowman

Yeah...according to my data, which is adjusted to reflect the expected on road Crr (and at an 85kg total load) it's a 4-5W difference for 2 tires between 30-40km/hr.

Power scales linearly with bike speed (for a given mass and road condition - also assuming below the "breakpoint" pressure).
The rolling resistance force, by definition (Froll = Crr *m) is only proportional to mass.
The power to work against that force (i.e. rate of doing work) is P = Froll *V

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http://bikeblather.blogspot.com/

I think the fact that it is a "tubeless ready" tire makes people think I has to be run tubeless and scares them away.

The thing keeping me from giving it a shot (with a latex tube) is how notoriously difficult road tubeless tires are to install/change.

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/kj

http://kjmcawesome.tumblr.com/

Yes, you've mentioned that. You need to load a mass on a test rig anyway, so I think it probably could be better served with a damper between that mass and the test article.

Or, you just make sure you never inflate your tires too high, and go with the regular roller tests to sort out what to use (since that's an effective way to measure casing/tread losses) ;-)

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http://bikeblather.blogspot.com/

Well, to be fair, what you mention above pretty much ONLY applies to the new Flo wheels, since they happened to optimize their design around that tire's specific, somewhat parabolic, shape.

Data on other rims might not match that.

I think I've said this before, but if I personally had the opportunity to do that sort of shape optimization, I probably would have started with a more round cross-section tire, if only because the lowest rolling resistance tires tend to be of that x-section.

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http://bikeblather.blogspot.com/

   
Way back in ancient Slowtwitch history, long before Al Morrison started his roller tests, I did a bunch of my own roller tests. There were two big revelations:

* Tufos suck
* Continentals suck

And I mean they really sucked -- like 10-15 watts sucked. Not just the GP3000s, but also the GP4000s, "Attack/Force" and the Supersonics. There were PerformanceBike brand $10 tires that rolled faster than the Supersonics.

I got a huge amount of flack for that at the time, because they were probably Slowtwitcher's two favorite tires. But the data is the frickin data. The absolute suckitude of the GPs was confirmed by a Tour magazine study (on Continental's own equipment!!).

Since then, Continental switched to their "black chili" compound and apparently their tires have gotten a lot faster. But I will never trust them and never buy them -- because they were clearly selling really crappy tires that they knew were slow for years. Seriously, their own test rig showed their tires were crap. So I don't care if they are making better tires. I still don't trust them.

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My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers

I'm not so sure it's necessarily fastest.

The bicyclerollingresistance site shows it at a less than 2.5W difference (in his testing) as compared to the 24C Turbo Cotton. However, considering that he tested the TC with a butyl tube inside...which I've found to add ~3-4W per tire...and I've also found that a latex tube doesn't add anything vs. running a tire tubeless, I can't really say if it's actually lower Crr or not. At least not until I test one myself.

It would be interesting to know how many of the folks you've asked had previous experience with tires like the TC, and with using latex tubes. It may be that they're raving about it because they're finally experiencing a quality setup ;-)

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http://bikeblather.blogspot.com/

I have a Corsa Speed in my sweaty palms as we speak. The Cottons are on the way and the rollers stand ready. I'll let you all know.....

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My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers

Let me talk to you about my learning of the possibility of effectively plugging a large puncture in a road tubeless tire from the outside, and without breaking a bead...makes the prospect of dealing with a puncture that sealant can't handle on the road decidedly less sucky...

Genuine Innovations makes a kit with the insertion tool and some rubber coated cords. I've experimented with a small piece of cloth (pinkie nail-sized, cut out of a t-shirt) that plugged an ~2mm cut in a road tubeless tire just this past weekend. Since the cotton seems to work well with the sealant to form a good plug, I'm thinking some small lengths cut from a roll of cotton butcher's twine, along with the GI tool, just might be the solution for an inexpensive repair ;-)

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http://bikeblather.blogspot.com/

Well...it IS still fairly new...and as I pointed out above, the jury might still be out on how fast it actually is in comparison to the competition. So it doesn't surprise me at all it's not mentioned more.

edit: Oh...and it's also only available in 23C, which sort of goes against the current trends...

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http://bikeblather.blogspot.com/

I recall all of that...and if you remember, I was quite shocked that my first test of the GP4KS model rolled as well as it did...

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http://bikeblather.blogspot.com/

Yesssss....he's baaaaackkkk! :-)

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http://bikeblather.blogspot.com/