noone is worried about the bad aero properties of GP TT 23 - swissside article 13

I am actually wondering whether not to run Conti FORCE on the front (since i have zipp 808 so wider tires) and Tubo Cotton on the back?

any views?

Kinda fat for the front, IMO. But not a bad choice if you want some puncture resistance.

I forgot about that SwissSide aero test on the GPTT.

Just looked at the article.
Am I right in thinking the GP is like the supersonic?
So a 23mm supersonic would be a good front option?

the GP was good, the GP TT was not good

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So don't run the GP TT on front? Does the aero benefit (or lack thereof) matter more for the front then the rear? If so, if your running 808 and Sub-9 both wider wheels would it make sense to run a TT or most "aero" tire on the front and look at SW TC or Cont TT on the rear?

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Best thread on here in a long time keep it going! Ive been liking Force/latex tubes F&R on my road bike for some time, rolls fast, comfy and no flats

On the front I'd definitely use an narrower, aero tire. For drag and cross-wind stability, both.

The rear wheel being in a drafting position makes it less sensitive to tire width. On the rear there is usually more weight, making Crr more important.

So a 20mm supersonic, even on a wide rim?

I am trying to back into your 2.5W figure from the chart referenced.

The Hed Jet 6+ with TC 24mm looks to come in at 0.025 M^2, while the same wheel with the SW Turbo 22m is 0.018 m^2. The difference being 0.007 M^2. Using the rule of thumb formula below, doesn't this make the 22mm Turbo 7 watts faster at 30mph?

0.1 lbs (50 g) of drag (at 30 mph) = 0.5 s/km = 5 W = 0.005 m^2 CdA = 0.0005 Crr

Now, I don't go 30mph, and I know that drag is not linear, but it seems like the 22mm Turbo has a great deal of aero benefit as compared to the TC 24mm.

Am I missing something or doing the calc wrong?

Now, the TC24 may be overall faster. We have to take down the aero drag for speed, while probably increasing the CRR differences due to road surfaces. I haven't seen roller tests of the SW Turbo TT 22mm tire, but if you look at the spread between the 24 and 26mm versions of this tire you might be able to back into an estimate of CRR. Back of the napkin this looks to give the edge to the 22mm tire if you go 30mph, and if your surface is super smooth. If you are slower, and if the roads are less than perfect, it seems that the 24mm TC takes the overall lead.

.0205 not .025

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Unless the Crr is so good on the TT, or the yaw angles are guaranteed to be low

Otherwise use GP SS 23mm

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No. 20mm SS tests slower than 23mm GP4000s at zero yaw

The tire to use is probably the 23mm SS. Top of chart Crr and not bad aero.

Or, a "magic" attack backwards if you can get one. Same Crr as SS 23mm and same aero as GP4000s

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But the article above seems to suggest the gp4000 isn't aero, or am I reading it wrong?

Which tyre is the GP? Is it the supersonic! Confusing!

How can I tell I have one of those magic attacks? Should it always be mounted backward whether or not it's magic? I'm currently running 4000sII but have an attack and a SS on order, both in clincher for my 808FC.

I have a sub9 disc tubular in the back which has a 22mm conti sprinter. Should I just go for the lowest crr with puncture protection or what would be recommended? I have a seat tube so I'm thinking aero is not top of the priority. TC in the back?

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TC or Force

Always backwards Attack

Have to roller test the Crr to know for sure

GP4000s only beneficial at high yaw, i.e. slow riding or Kona. Does not roll that well

SS 23mm probably best for front.

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which article?

the thing about the GP4000s 23mm is that it's aero *at yaw*, a condition most fast TT'ers and triathletes don't see that much, and the other thing is that it doesn't roll as well as the fastest rolling tires, and when you do the math the less aero tires come out ahead because of their greater Crr savings.

GP SS 20mm - OK aero and OK Crr, best for H3 wheels
GP SS 23mm - very good Crr without a puncture belt, OK aero, probably best front tire for wide wheels
GP TT 23mm - very good Crr with a puncture belt
GP 23mm - a very good aero tire
GP 4000s 23mm - very good aero, OK Crr
GP 4000 23mm - more durable version of the 4000s
GP 4-season - even more durable version I would imagine
GP Attack 22mm - very good aero, very good Crr if you can find a "magic" one, puncture belt
GP Force 24mm - very good Crr, puncture belt, great rear tire

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My front rim is <17mm internal and 26mm at the tracks, so a SS23 is only ~23.5mm wide. I would stay below the width of the brake tracks on the front, if possible.

Still, a 20mm SS will be more aero (particularly at high yaw) so it's a tradeoff between that and Crr and potholes. I used SS20 on this rim last year.

20mm SS tests slower than 23mm GP4000s at zero yaw

Where have you seen that?

James Haycraft's data at A2 on Jack Mott's website

https://docs.google.com/...On560/htmlview?pli=1

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I dunno.... Based on Tom A's testing I think the SS 23mm might have the aero to overcome the 20mm poor Crr, especially after what James Haycraft found

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Without repeats and error bars I'm kinda skeptical. Very, actually. I've heard from a few fast riders who do WT testing that narrow is substantially better for aero, even on a wide rim.

There are other good reasons to use a bigger tire though besides Crr, if your roads are a mess.

nice summery, thank you! Were would you put the Sworks TC in there?

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

That list wasn't a ranking BTW

The TC is very good.

Check out Tom's Crr chart at bikeblather.blogspot.com

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no i know, but nice to see just laid out like that! I need a chart of yaw, wheel and tire, and what to run then! If anyone wants a weekend project! lol. Will check out the article thanks :-)

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2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz

This is true. For me though, josh at zipp's advice about the penalties of over inflating vs. the benefits of under inflating plus my weight and chosen discipline (IM) on average roads leads me to wider tires, especially since I am the owner of a magic attack, fast force, and fast SS 23mm

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