And, surprisingly, they aren't that much slower than my 23c's. *scratches head*

I heard wider tires (of same tread with same bike & rider) are faster. Can't remember the reason.

I'm equally fast on my 700 x 28 Gatorskins (112psi, no tread) as I am on my 700 x 28 Randonneur Crosses (85psi, moderate tread), and nearly as fast on my 26 x 2.2 WTB Graffiti SF (60psi, light tread.)

I just switched out the Ritchey SpeedMax 32's for some Nimbus 28's. Somewhere between 1-3 mph faster while cruising (the 32s ran about 10 psi lower pressure).

The reason that I've heard is that you can blast over the rough ****, rather than ride around it.

I'm pretty turbo on my 32c's.

Properly inflated, the actual contact patch of the tire should be roughly the same.

But people tend to be a tad slower on the fatter tires because they run them at a lower psi, creating a wider contact patch of tire to asphalt. Plus the fatter tires and tubes are heavier.

Also a jittery ride on high pressure skinny tires is the feel of rolling resistance, you feel the bike bouncing up and down off every little imperfection in the surface

I've heard something scientific about why fatter is faster. I'll bet someone pipes in with that ... I think it's fewer pounds per square inch (less friction) without increasing the longitudinal footprint.

From all my reading on forums and personal experience, size switching tends to be a one-way street. Once people make the move from 21's, 23's, or 25's to slightly larger sizes, they don't go back. They notice the improvement in comfort and can hardly tell any speed difference. But I've rarely heard someone moving back down in size because the weight was intolerable. It's kinda like the switch from shorts to bibs.

you won't find me racing on 32s anytime soon.

but as for my commuter, I think I'll stay above 28c from now on.

FWIW I run my 32s at the same pressures as the skinny tires - 110psi rear, 100psi front. Lower in the rain.

Those pressures seem a little insane for 32c. I am pretty sure that the max recommended inflation on mine is 85 and I see no reason to go past 80 in the rear unless I have a ton of groceries.

I stay around 80 psi on my 32's myself. My tires are 650b and I have 26" x 1.5" tubes inside.

Same experience here. I'm fully convinced my next road bike will be spec'd for 28's with minimalist fenders. The speed difference isn't worth it on our crap roads.

The sidewalls on the Hardcases say max of 125 I think. The listed max is definitely over 100, but I'll double check tonight when I head home.

Why do wide tires roll better than narrow ones?


The answer to this question lies in tire deflection. Each tire is flattened a little under load. This creates a flat contact area. At the same tire pressure, a wide and a narrow tire have the same contact area. A wide tire is flattened over its width whereas a narrow tire has a slimmer but longer contact area. The flattened area can be considered as a counterweight to tire rotation. Because of the longer flattened area of the narrow tire, the wheel loses more of its “roundness” and produces more deformation during rotation. However, in the wide tire, the radial length of the flattened area is shorter, making the tire “rounder” and so it rolls better.

Why do Pros ride narrow tires if wide tires roll better?

Wide tires only roll better at the same inflation pressure, but narrow tires can be inflated to higher pressures than wide tires. However, they then obviously give a less comfortable ride. In addition to this, narrow tires have an advantage over wide ones at higher speeds, as they provide less air resistance. Above all, a bicycle with narrow tires is much easier to accelerate because the rotating mass of the wheels is lower and the bicycle is much more agile. At constant speeds of around 20 km/h, the ride is better with wider tires. In practice, the energy saving is even greater than in theory as the elasticity of the tires absorbs road shocks, which would otherwise be transferred to the rider and so saves energy.

Yes! There it is. Thanks Kojak!

Thanks Kojak!

That only takes rolling resistance (RR) and weight into consideration. Wind resistance/drag is a major factor when riding at the same speeds as Pro peleton riders does, since RR remains more and less constant at different speeds (AFAIK), while wind resistance rises dramatically when speed is increased.
So narrow tires have lower drag, lower weight and adequate low RR which is why Pro Peloton riders rides 20-23mm tires at most races. You probably know all this, you just forgot to write it

Pro riders do ride at insane fast speeds however, so most commuters will probably benefit from the added comfort of wider tires without sacrificing any noticeable speed.
For me the "sweet point" between speed (RR, drag, weight) and comfort is 28 mm tires. Others will prefer bigger tires, others again are happy on their racing 23 mm tires.

--
Regards

I should have made this clear from my original post, these paragraphs are directly off our website; probably authored by a Schwalbe engineer. And for the record, wind resistance was addressed, but probably "lost in translation"; they use the term "air resistance" (see 3rd sentence).

Cheers,

gb

my favorite tire for commuting this season has been 700x35 but just today rode some 27 x 1 1/4 armadillos and found their width satisfactory. I was a bit careful about wheel placement, whereas with the 700x35s I was a little less worried

I just checked mine. They actually go to 95 not 85. Comparing across tire types is kind of futile but I've just never heard of 32c tires being inflated that high.