Disappointed they are not making a 24mm. I wonder if the 25mm will fit any better on my P2 than the 4000!?!?

Really, marketed sizes have almost become irrelevant as measured sizes are almost always different....although rarely smaller on a road tire so your point is taken.

Michelin suggest pressure between 6 and 8 bars on the road.
6 bars (approx 87 psi) for 50kg rider
8 bars (approx 116 psi) for 80 kg or higher

at 77kg, running my rear wheel on the dry between 110 and 113 is OK for me depending on road quality.
Alu training wheels are comfortable, and do the job.
Racing, generally better road quality, feel OK with carbon race wheels (55mm).

Rec. from Continental for GP4000S2 :
23mm : 110 psi (7,6 bars) - max 120
25mm : 95 psi (6,5 bars) - max 120

I suppose this is for average weight rider : 70kg ?

Considering at 77kg (+10%) I'm in the high range, adding 10% to 95 psi, and running 105 psi (for 25mm rear wheel) make sense for me (Ok I'm slightly above).

Again, when wet, go down to 90/100 PSI (F/R, when both 25mm).

yes, but the RR more than made up for it. With the gp5000 the gap of RR has seemed to have decreased significantly

Weird. I assumed all TLR rims were hookless these days.

170lbs is a bit heavy?

So is hookless really an MTB thing? All my other TLR rims are for CX/MTB.

In terms of comfort I'm inclined to go lower than that. There's no need for pressures that high. As I mentioned, I'm heavier and ride a lot of very poor roads yet I don't suffer pinch punctures. Beyond that it's about performance, where a compromise between comfort and rolling resistance is probably justified in long distance racing but comfort wins out in training.

Early accounts are that the 5000's fill out a bit smaller than the same nominally sized 4000SII. For all intents and purposes, a 25c 5000 seems to fit like a 24c 4000SII would have, if such a thing ever existed.

continental-grand-prix-4000s-ii-2014-vs-continental-grand-prix-5000-2018 (scroll to "Size and Weight Measurements" )

Michelin describe riders from 50kg (6 bars) to 80kg / 80kg+ (8 bars).

So, 170lb (77kg) is on the top of the range for them.

Pyrenean Wolf wrote:

We've gotten a bit more sophisticated about road tire pressures since that Michelin chart was first published. " 'Tis far better to err on the side of too little pressure than too much" :-)

https://silca.cc/...stance-and-impedance

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http://bikeblather.blogspot.com/

I'm thinking this may be the way too. I have been using gpTT 25 on both wheels, which are super fat Aeolus, 27mm wide at the brake track. It seems a 25mm gp5000 on the front may be the way to roll now.

Thanks. I think a lot of P2 owners on this forum will attest than a Conti 4000 larger than a 23 does not fit well on that bike (depending on the year) and may rub. I'm running 25's on mine, but it required liberal screw adjustment in the rear dropouts and is still pretty tight. Was just thinking a 24 might be a good compromise. At the end of the day, I guess I should be using 23s, but greatly prefer the 25s.

Pretty much...and its only real purpose is to make carbon rims easier to manufacture.

I have never had issues with punctures with the tt- plus it seems the 5000 isn’t all that much better

Lower hookless rim lips are less prone to rock strike and damage.
Also less likely to cut the tyre when pinched in hard landings.

Thanks for the read, it is really very interesting test and resulting datas.

One parameter of the test does not appear (or I missed it), the speed of the test (or different speeds for different surfaces ?). Do not know if speed have a significant impact, but possibly can.

From these tests and results, I understand breakpoint pressure for 190lbs (bike + rider) with 25mm GP4000s2 on carbon wheel and TT bike for the kind of road I'm going on is probably : 100 (coarse asphalt) to 110 psi (new asphalt).

Being 3 or 4% heavier (bike + rider + water +... = 197lbs), possibly 100 to 114 psi for me.

So pressure I was using (113 psi for 25mm) was optimal for good asphalt, but not for rougher ones.
So will move back my training pressure to 100 (for 25mm) and test. And understand the "lower less a problem than higher".

The last graph also explain the interest of the TT vs GP5000 in real world : more supple case will enable a "further" optimal point, getting a better Crr from higher pressure, due to "later" impedance impact. Interesting. But TT too fragile for me :-)

I must admit I am hopeless at deciphering the results of the CRR testing.

At the moment I have 23mm Conti SuperSonics on Zipp 808 FC (front and rear) running latex tubes. I was using them for the last two seasons and they are up for a replacement. Up until now I was thinking about picking Conti GP TT next, 23mm for the front (aero) and 25mm for the rear (added comfort)

would the new GP5000 make a better replacement? Should I pick 23mm or 25mm ?