Great data for sure and it pretty much triple confirms the 23mm conti 4000 is the best tire all things considered.

Which, knowing that this wheel was analytically optimized around the shape of that tire, isn't quite surprising ;-)

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http://bikeblather.blogspot.com/

A lot slower in my testing (pair of tyres, in bike). GPTT measures 1.2mm wider (on same rim) which is significant. Narrower than the rim seems to make up for shape sins.

Out of interest since I guess you might have some good background knowledge of this. When you say narrower than rim are we talking brake track width or widest place on rim? I've been wondering about the penalty size of running say, a 26.5mm tire (actual width) on a rim with a 25mm brake track but 28mm maximum width.

Narrower than the brake track in this case - rims tested measure 24.4mm but don't really bulge beyond that.
Hoping to shed more light on wide tyres later in the year.

Thanks for the reply.

I've been wondering where the aerodynamic hit happens in a case like the one I mentioned - tire width somewhere between brake track width and maximum rim width. Already at low yaw or really only (or primarily) due to earlier (and maybe) worse stalling. Maybe a bit of both seeing Tom A's testing of Turbo Cotton.

With something like the HED Jet Plus you have to use very narrow tires to get tire width no more than brake track width - the 23mm tires I've tried all bulge out a little bit.

Conti is the default clincher choice in Europe from my observation. Even the Specialized Concept stores sell them.

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29 years and counting

A bit selfish of me to expect Flo data to help me choose what tires to put on my non-Flo wheels, but do you think we can extrapolate an educated guess for a fairly typical use case?

For my example, I'm on Hed Jet 9 up front and a narrow flat disc at the back.. happens to be Renn 555 in my case. Currently I have 23mm Conti 4000s II on the front, and Attack on the rear. But that tire was chose with aero also in mind and I am conscious of how much my P3C fares the rear wheel. Basically only the bit below the height of the bottom bracket sees much wind at low yaw.

My Hed is C2 so pretty wide rim and the 23mm Conti on there now doesn't bulge wider than the brake track to my eye, perhaps the Flo data is a decent match here. So front is a Force 24mm in all probability. Force on rear as well? With aero less important CRR rules but still good on that tire. Perhaps though I can afford a bit of comfort with my very stiff disc and go 4000s in 25mm without much penalty? I guess Force is still a very good choice and 24mm still wider than my 22mm Attack.

I like this study!

In fact ignore me it seems obvious that Force 24mm is probably best bet front and back in my use case. I was just thinking on whether the combined table is useful for the rear on a frame that fares very well, or whether the crr table becomes dominant. But when it is the same answer either way it doesn't really matter!!

ETA a bit of a shame that over here in the UK the Force is almost always sold in a pair with the Attack, with the Attack ironically meant to be the front tyre.

Pretty much all I see with regard to data on crr and drag for tires is clincher, for those of us still running tubular where do we go to get this level of testing and data? Yes I know the most recent clinchers are faster all around, but I've got AU$2,500 wheels that I'm not going to replace to go with clinchers.

Yep, I'm committed to tubular for a few years yet, for the same reason. I run SLSpeed 24mm tubs on an 808 FC/900 disc.

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29 years and counting

as long as you are using it without a bike. kind of like the BC comic strip

what consideration is there for imaginary power to spin in all this and how a wider tire(more surface area) might increase that as well?

FYI the 24mm Force is absolutely ENORMOUS on Jet+ rims. I would be somewhat surprised if Flo's findings held true for the Jet+ (though I would be happy since my entire rim collection is Jet+ at this point).

You are right that the mounted width of the tire is the key feature here..I know that everybody wants to be able to draw conclusions across makes and models and brands, but at the end of the day, the only way to know for any specific combination is to do the testing.

I have to give massive kudos to FLO for this data. I know everybody always wants more data on more tires and such, but having done what they are doing myself, I can say that this single chart they've published here probably represents $25-30k in expense, not including the time of all involved. This is a huge undertaking.

In 2004 I wrote a white paper that was the basis of our 808 development where we theorized and had some rudimentary data that the rim width had to be at least 105% of the tire width (mounted measurement, not sidewall measure). We later learned with Firecrest that the shape could overcome some of this, but much of what I see today has that 105% number still holding. The difference now is that the bead seats of clinchers have widened which widens the tires considerably. We posted a blog post about this as silca.cc yesterday..but it's much harder now than it was on the tubular days where a 23mm tire was always they same thing on every wheel.. Here's the chart in our blog post..you can see that the same tire can be very different things depending on what wheel you are mounting it on.
Josh

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Am I the only one who is shocked that the 25mm gatorskin is only 4 seconds slower over 40km compared to the S-works turbo (non cotton)?!? Not to mention the Schwalbe one only 2 seconds faster than the gatorskin.

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Thanks for chiming in, Josh.

When you mentioned those 105%, is that brake track width or actual maximum rim width that has to be 105% of the actual mounted tire width? And with with some of the newer blunter (Firecrest'y) shapes this can be a bit less, say 102-103% perhaps?

which to me, implies that we want to run narrower tires on these wider bead rim wheel and not wider. ie making beads wider to accommodate wider tires actually means we need narrower tires to keep them aero. On a jet+ rim, I don't think you can find many 23c tires that will meet the 105% of widest portion of the rim(not going to be narrower than track on those)

I have measured two 23 mm tires on my Jet Black and they are ~26 m and ~27 mm, respectively. I'm not quite sure of the actual maximum width of the Jet Black/Plus. I've tried and measure it with my calipers and getting around ~27mm, but I'm not entirely sure how accurate that measurement is.

I realy wish Zipp and HED would do this for their wheels.

Any bets that the Zipp Tangente tire is best on the Zipp wheels?

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Suffer Well.

If this is true, that's a crazy investment for a company of their size, and that's only on the tires. It's also ridiculously expensive for what it is.

Totally OT, but curious if you have a sense of the capital required and rough operating costs for a win(d) tunnel. There would seem to be a great opportunity for some entrepreneur to create a cycling industry specific wind tunnel somewhere in the eastern corridor, and monetize wind tunnel time on both a B2B and a B2C basis.

One word of caution on the Force data. The values shown were for a Force tire that rolled at a Crr of .0029. I've also tested another tire of that model at .0034. Due to time constraints, when I roller tested the tires that Chris and Jon sent me, I didn't retest their particular Force tire.

Once I am again able to ride a trainer (due to injury that's not possible right now) I plan on rolling the particular tire that they sent me.

So...as with the Conti Attack, it appears that how well it rolls can be a bit of a crapshoot for some reason. Only Conti knows why this may be for those particular models. Other model tires from them (i.e. GP4000S, SS23, etc.) don't seem to vary like they do.

I guess I'm saying that unless you know for sure you got the "fast" Force tires, I wouldn't make such strong conclusions ;-)

(Thanks for pointing that out, Heath!)

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http://bikeblather.blogspot.com/

It's not surprising...none of those tires (the 22C S-works Turbo, that is) have stellar Crr.

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http://bikeblather.blogspot.com/

My surprise was leaning more to thinking the gatorskin was worse than this - not that I'd ever run one regardless.

Thanks for spending time on this Tom!

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Quoted for irony.

Scott

Pretty sure the 23mm GP 4000 tested best again for the Zipp wheels.