asgelle

The difference is now we have power meters to go along with the kinetic model so direct measurement and testing is available to the masses.

Lazyass

And yet the new generation isn't any faster

asgelle

Speak for yourself.

Lazyass

No.

ninja2

very entertaining thread, like it! lots of of good info; here is my 2.5 cents - after having read everything there was to read, i decided to take time some years back and did the tests - 8 different tire/tube/size combos, 2000km each test,using latex and butil tubes , tires 25c, 24c, 23c, conti 4Ks, vittoria corsa CX, SR, Pave and now riding on corsa G's. without trying to offer astronomical accuracy, using latex tubes improves speed by 4-6%. on the fair quality surface road, slightly wider tire is slightly faster. i'm using 25 c rear and 24c front tire on the paved trail bike and 24c rear and 23c front on the nice pavement road bike. rim is 15mm inside, pressure 110psi on trail wheels, 115 psi on fine pavement road wheels. important to say - the tires measure withing 0.5m of the nominal dimensions when inflated to the mentioned pressure. the site referred to in the OP is ok, but saying that conti is better than vittoria (which they do in the article) is something my experience strongly denies. i've no preference in either brand, no bias, just tried different combos and am using the product that's proven better for me based on the real life experience. small differences,but worth trying on your own and deciding based on facts. after all, we're all a bit different from one another.

dmanthree

Last year I switched from 28s to 25s and I noticed a small speed increase. I posted that here and while I wouldn't call some of the replies attacks, well, there were some doubters. But my results were not fake. I'll stick with 25s, thank you.

Bah Humbug

To have a point, you'd have to prove that the new generation isn't any faster than they would have been otherwise.

asgelle

Ball Bearing

Two more millimeters is an 18% increase in air volume. I notice a big difference.

McBTC

I'm pretty much satisfied to be there too based on my seat-of-the-pants experience from touring. Had Champion rims that'd take anything and I tried out 23 to 32 ('Expedition') tires over time. We all used 25s with loaded rear panniers. It was always 23s for spinning around after work and day rides--you could tell the difference.

Now, current-day 23s are like the old 25s so going with current 25s is already like heading to 28 sizing back in the old days. Going to actual 28s today would be like putting on those old 32c Specialized Expedition tires (in the BicycleRolling article Conti's 32s were coming in at 31)... maybe if I was touring in Nepal. My feeling is that, instead of 28 , why not trade in the road bike and go with 100 psi 26x1.25" Specialized Fatboys on a hardtail?

Spoonrobot 

tagaproject6

Potential, this thread has!

aplcr0331

McBTC

Still, a metric mentioned in the article is the amount some riders are willing to spend on wheels to gain an aerodynamic advantage, which if the psi is held constant is where the net difference in performance comes from going from 25s to 23s. The 25s save a couple of watts due to reduced rolling resistance (if you can pedal 18 mph at the same psi as the 23s) but the 23s are saving up to 9 watts when going against the wind. In doing 11 mph at 45 watts and doubling the watts to go 15 mph, my guess is that saving 9 watts probably is noticeable compared to saving 2 watts. I had a couple of rides this year where half the ride was in ~20 mph headwinds and you pretty easily feel everything you do to improve aerodynamics.

Seattle Forrest

I think all of Enve's modern road wheels are faster in 25 than 23 mm. I'm riding their 4.5 ARs which are made for 28 mm tires, which they stretch out to about 33 mm.

Seattle Forrest

HTupolev

It's all about the tire-rim combo, the intrinsic effects of a 2mm difference are miniscule. In reasonable circumstances, the only way that there's going to be a 9W aero diffence between a 23 and a 25 is if the rim was designed to be aerodynamically paired with a 23mm tire, and the 25mm tire crosses a width threshold creating an aerodynamically poorly-behaved pairing. Paired with an appropriate rim designed for 25mm tires, there should be no such behavior.

canklecat

I switched to 700x23 on the front and 700x25 on the rear. Now I'm faster and more comfortable. The front end gets to the finish faster. The rear end is more comfy.

redfooj

Lovely.

Id love to see this quote everytime someone bangs on about aerodynamic overshoes or the new brake fairings and hidden clamps on their frame

Racing Dan

Before worrying about micro gains from aero this, that and the other, ppl should learn how to ride a decent aero position for more than 1 minute at a time and on really rough roads like cobble you can safely ignore aero and just go with the fattest tyre that will fit in the frame. - Maybe not the pinnacle of science, but for for thought:

asgelle

No matter what position I ride in, I still have to push the bike through the air. The benefits from a low drag (or low rolling resistance) bike are there no matter how I ride. Maybe not the pinnacle of science, but logic.

himespau 

Yeah because what we really want is less friction between our tires and the road, especially when cornering.

asgelle

Are you deliberately misrepresenting what I wrote or do you legitimately not understand the difference between traction and rolling resistance?

himespau 

I swapped out the inner tubes on both wheels the night before last. Front had had a slow leak and the rear just didn't have a long enough stem to comfortably grab with the head of my most commonly used pump. Set PRs yesterday on every segment I rode yesterday (except the one where I came around a curve to find some d-bag had parked his truck and big trailer in the road and there wasn't enough room to get by) and set a new power peak for riding outdoors. All while feeling like crap, not having trained this year, and not being sore today (yet). Therefore, putting Schwalbe butyl tubes in your tires makes you a faster rider. Done and done. Better go update my blog.

himespau 

No, I was agreeing with you in saying that the person who was describing rolling resistance as traction was an idiot, not you.