.0001 is still over 3%.

right, but other tires have gained like 10% between 23/25 and 24/26 options.

just wondering

I think what Tom says is right.... it's a product of tread AND shape... and so it's possible to max out on one and so not get much change from the other when going wider. I'm going out on a limb and saying that the current crop of .0029 tires on Tom's chart won't be topped by much more than that .0001

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oki last one - i jsut changed set up for 25mm - what is the usual difference in psi between the 23 and 25mm

About 1 bar , don't know the psi

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-shoki

10-15 psi drop is probably typical. If you're riding on good asphalt, I'd keep it in the 110-120 psi range if you want the lowest Crr.

How does the Force perform on a Renn 555 disc? Is it a good fit?

It will bulge out a fair amount. Force is a little wider than a GP4000.

Would I be better off with the GP4K that I'm using now on the Renn disc? Should I use an Attack on the disc; it's what I'm using on my front wheel.

Michael

IME the Attack usually has better Crr than the GP4000, but that isn't always the case. I'd use either before the GP4000.

So your preference is the 23 mm Supersonic, correct? Too bad the tire life is so short.

Race tire, optimized for the purpose.

Well sort of. It might be even better with some boundary layer tripping grooves.

Actually having a short life is a good thing. Tires tend to lose their aero properties pretty quickly. The lack of tread on the SS has you replacing the tire more often and so it might actually be a positive.

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Just got my 24/26 mm tires. What's a good starting pressure for these? (I'm 165 lbs). I'm thinking 105/100. I have always ran gp4000s and run 100/105 psi but I feel like they should be higher.

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What width rims and what tubes? On my uber-wide Hed+ rims (21mm internal width, which adds ~2mm to the mounted width) and using latex tubes, I run 80psi front/rear.

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http://bikeblather.blogspot.com/

Zipp FC 808 front and super 9 rear. Vittoria latex tubes.

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blog

I would probably go more like 90/95psi. I also weigh 165#

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http://bikeblather.blogspot.com/

Thanks. How do the width's compare from the Zipps to your HED's? The HED's are wider?

With running a wider tire in the back (26 mm), wouldn't a higher pressure in the back negatively impact stability (narrower contact patch)? I know it's minimal and probably not even noticeable, I'm just thinking theoretically in my head.

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The Heds are wider and add ~1mm more to the mounted width than the Zipps.

When I was running 24F/26R on my road bike, I would typically inflate both to the same pressure.

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http://bikeblather.blogspot.com/

Hi Tom,

I'm running the same Zipp 808/Super-9/Latex set-up but is lighter coming in at 150 lbs. What tire pressure would you recommend? I'm doing IM SA on Sunday. The road quality is probably not great. Would you run a even lower psi on South African tarmac? :)
Hoping the road quality don't eat my Turbo Cottons alive haha

Cheers

Probably reduce by ~5psi...you be the judge ;-)

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http://bikeblather.blogspot.com/

I'm running a Flo 60 front, and Renn 555 disc rear on my TT bike. Would the 24mm SS tires be my best bet front and rear? I currently have an Attack front and 23mm 4000s rear. I just picked up a couple of S-Works 24mm Turbos, though I'm thinking about putting them on my road bike. With my rims, but is my best option?

And at 150 lbs and latex tubes, what would be a good tire pressure? I'm currently running 100 psi front and rear - likely too high.

Does anyone have any suggestions or experience running turbo cottons on a Zipp super9 on a Cervelo P5?
Is it possible to squeeze a 26mm in the rear? I'm currently running 23mm supersonics and looks like there is a bit of room still.
Or would I be best sticking with 24mm front and rear.

Cheers

Phil

I run a 25 conti 4000S on my super 9 disc and P5. Did have to back out the dropout screws for clearance tho.

Thanks. May go with the 24's then just in case!

Should note can't get larger than 23 on front. Rubs the brake and downtube.