Drew Eckhardt 

You can save 20W at 20 MPH (about 10%) running more supple tires than Gatorskins.

Gatorskins are a flat resistant tire that isn't too horrible riding.

GP4000/5000s are fast tires that are fairly long wearing and flat resistant.

The newly introduced 5000s come in 32mm wide, up from the 28mm maximum of the GP4000SII, up from the GP4000 25mm limit.

wolfchild

It's neither the weight nor the rolling resistance...it's the rider.

MattTheHat 

Some people enjoy riding faster than others. Speed up...enjoy the ride!

hillyman

Then The 33 is the place for you to be

HTupolev

No, the 33 is for bicycle racing. We're talking about wanting to ride a bicycle fast.

aclinjury

That's not exactly what the graph shows. The graph shows that rolling resistance also varies with tire pressure, but I get what you're saying. However, on a smooth surface, a 25c pump up to high pressure will outperform a 32mm tire quite handily!

hillyman

Ah, you mean fast, just not fast. Now that's clear

HTupolev

Nothing to do with the degree of fast. The point is that the pursuit of performance doesn't imply that you're interested in the formal sport of bicycle racing. This is true even if you're interested in some sort of formal bicycle sport: randonneurs often care about tire performance, for example, but randonneuring is generally regarded as a different sport from racing.

Also, if someone wants to ride a bicycle as fast as possible, the sorts of bicycles used in the 33 are often very poor choices. If you're riding flat ground, for instance, a velomobile can dramatically outperform any road or TT/Tri bike. This is because bicycle racing is not about riding the fastest bicycles, it's about racing bicycles.

hillyman

Fascinating. I didn't realize so many different ways to go fast. So the bike you ride is much different than the bikes they race with?

HTupolev

Nothing that I said has much of any relevance to what bikes I ride. I'm not a velomobile person, for instance, I'm just pointing out that they exist and are not really within the scope of the 33.

All of my bikes would be legal to use in a road race in the USA, although only one wouldn't look at least a bit out of place.

Kapusta

If a 32 is slow, it is not because it is a 32. It is because it is a crappy tire.

Anyone that thinks a 32 cannot be incredibly fast (lightweight, low rolling resistance) has not tried a Compass Stampede Pass.

Drew Eckhardt 

The graph has rolling resistance plots for the GP4000SII in 20, 23, 25, and 28mm widths.

It shows shows that at 116 psi, rolling resistance drops 20% from 0.49 (units not specified, could be kgf total at 50kg load per wheel) at 20mm to 0.39 at 28mm wide.

Conversely accepting rolling resistance of 0.45 you could ride a 28mm tire inflated to 85 psi, a 25mm at 94 psi, or a 23mm tire at 123 psi.

Or you could split the difference for some combination of lower rolling resistance and a softer ride.

3mm on a 700C tire moving from 25 to 28mm should cost 0.4 W from aerodynamic drag at 20 MPH assuming .5 Cd.

A Crr decrease from 0.0041 to 0.0039 moving from 25 to 28mm is 1.3 W for a 75 kg bike + rider at 20 MPH for a 0.9 W net savings.

Similar gains should be possible moving from 28 to 32mm at recreational speeds assuming you run the same tire which is the rub. Continental makes a supple 32mm GP5000, Compass makes low rolling resistance tires out to 40 or 50mm, but most manufacturers haven't caught up to clearance for that wide a tire coming standard on disc brake road bikes.

Doctor Morbius

Yes they are, but I want everyone to keep believing that the contact patch and rolling resistance are the only important metrics when buying tires. That way I can buy 700x23 tires on the cheap!

aclinjury

Right, that's what i said, tire pressures play a role.

Furthermore, the graph assumes a STEADY STATE rolling resistance, which is usually not the case unless it is a TT indoor.
If you do many multiple hard out-of-the-saddle accelerations, or in a steep (7%+) climb, where torque on the tire is not constant, then you also have to consider hysteresis loss of the tire on lower pressure vs that on higher pressure.
You can't just simply say "wider tires" roll better and ignore everything else, because road surface and rider's style should also be considered in tire preference.

Another problem with 32mm or wider tires is that most are usually not made with "speed" as the main performance factor, most are made with durability as a factor too. I would be very surprised if any 32mm+ tire would actually outperform a 25mm one on a typical road, even roads with many cracks on them.

Moe Zhoost

OP must have new tires now judging from the speed he moved away from this thread.

unterhausen

did he ever say what kind of tires he used? I have had some tires that felt like my brakes were on. Now I use 32c Gravel Kind slicks and they roll pretty well

5teve

Depends on the tire. There are slow feeling skinny tires and fast feeling fatties.

Sy Reene

Another couple of charts to throw into the discussion:

BCDrums

...as the wise man breaks wind, and is gone.

asgelle

Did you create these? Were the tests done on rollers or on the open road? If done on rollers they would ignore what has been referred to as impedance losses.

Sy Reene

No.. not mine. Sorry thought they might be recognizable -- these are from bicyclerollingresistance website. I believe they use a textured roller of some sort.
Link to source of charts:
https://www.bicyclerollingresistance...000-comparison

asgelle

So they don't include impedance meaning that while their results might be useful for comparing different tires of the same size, they can't be used to compare across sizes. There have been many discussions about how wider tires allow pressures low enough to avoid impedance losses where narrower tires require pressures that don't.

MattTheHat 

Could you let us know what the speed limit is for posting in General Cycling?

hillyman

I don't care how fast you ride or where you post my friend. My joke on the 33 was to YOU on the impressive numbers on your posts.
My comment on don't worry about speed is for someone who puts 32 tires on then not happy about the speed.

Wilfred Laurier

I haven't read all the replies, so this may have already been said, but 32mm wide tires are not necessarily slower than narrower tires. What will be slower is if you switch from lightweight racing tires with a thin tread and supple casing to a thicker and heavier tire with some flat preventative strip under the tread.

On a tour two years ago I was using Panaracer Pasela 70x35c tires... Paselas are known to be the most budget friendly lightweight supple tires you can buy. But I was getting lots of flats, so I replaced my rear tire with a Specialized Nimbus with 'Black Belt' flat protection.
I instantly went from coasting away from my group on downhills to having to pedal on downhills to keep up. Same size of tire, but vastly different construction mad a huge difference.

Epilogue: That slow-as-spit tire is also very long wearing, and I have a personal rule that I don't replace tires until they are worn or damaged, and these tires are tanks and unlikely to suffer any damage, so I am stuck with that tire for at least a couple thousand more kms.