If by "tire deflection" you mean the tire bouncing on a surface, that is a small part of "rolling resistance". Most of the rolling resistance is due to deformation of the tire as you weight and unweight the contact patch. If you increase the pressure in the tire, the tire becomes more rigid and the rolling resistance due to the deformation decreases which is why higher pressure tires roll faster than lower pressure tires. You do reach a limit where the tire starts to bounce and you lose energy but that is a small fraction of the deformation derived resistance.

The reason that wider tires have lower rolling resistance is because the walls of the tire deflect less as a percentage of their cross section and have a shorter section of deflected sidewall. The difference between a 23mm tire and a 25mm tire is about 5% but I suspect that going to a wider and wider tire results in diminishing returns because other factors, like weight and higher friction, come into play. Going from a 23mm tire to a 42mm tire probably isn't going to result in too many advantages. Going from a 23mm tire to a 25mm or 28mm results in only a small advantage without gaining too much weight or front surface area.

Fair enough. No one "needs" to increase their comfort while decreasing their rolling resistance. However, I think most commuters would consider that a win-win.

No. I unweight my saddle. I haven't figured out how to unweight my racks while riding. I have enough sense not to use a skinny 28 mm tire.

Get them rolling, yes. It doesn't take any more effort to keep them rolling though, except for their increased air resistance, which is inconsequential at typical commuting speeds. On the other hand, their increased momentum makes the bike's speeds a bit more stable in gusty winds (also inconsequential for commuting, but easily makes up for their increased air resistance).

You're reaching. They tested the same tires in different sizes, at multiple pressures.

Experiment is how science is done.

The experiment demonstrates what we would expect, based on theory. Wider tires roll with less resistance. No one is telling you that you have to give up your skinny tires, but your claim that skinny tires are faster in the real world is wrong. Full stop.

For commuting: I often carry things on the rear rack. That makes it impossible to unload the rear when going over bumps, obstacles - the luggage stays put on the rack - weighing the rear wheel. So, for commuting (loaded bike), I find that even nice 28 mm tyres are too thin. 37 mm is the sweet spot - not too heavy, thick, but still can be pumped to just 4 bars and absorb bumps. At least for the rear. For the front - 28 mm is good enough. On really rough pavement - fatter are faster.

Rolling resistance is mostly down to tyre quality. That has been my experience (11 km one way commute, flat terrain). Thickness is not that important. If I wasn't riding a loaded bike, with baggy work clothes, perhaps weight and air resistance of tyres would be significant, but in my situation - irrelevant.

P.S. Jumping from 23 mm to 28 mm tyres has resulted in a vast improvement in terms of comfort and flats - 23s I had to pump over 6 bars which made easier for sharp objects to stick to and puncture tyres. My experience has been that 6 bars is a limit below which tyres get a lot less flats. Even experimented with 23s - pumping them to 6 bars. Too soft, but less flats. Get below 4 bars on some fat tyres: hell, you don't even need any flat protective belts, or anything - bombproof!

I have not found fatter tires to be faster but instead slower. If there is any benefit to lower rolling resistance -- and that is debatable -- it is largely or completely offset by heavier weights. Simply put, most fatter tires are also heavier, and that slows you down while climbing and accelerating. That said, I have several bikes with fatter tires and enjoy riding on them because they are more comfortable and provide better traction on rough and unpaved surfaces. If I want to go faster, however, I'm gonna grab one of my bikes with lighter (and thinner) tires.

Air resistance isn't "inconsequential at typical commuting speeds" unless the speed is around walking speed. At 20 kph (12 mph), it takes nearly 100 watts to move a conventional "Dutch" bicycle down the road. A racing bike takes around 40 watts. Most commuter bikes are going to fall somewhere in that range and probably closer to the Dutch end of the scale. If you increase the speed to 25 kph (15mph), it takes 100 watts to overcome aerodynamic drag on a racing bike and a bit over 200 watts on a Dutch bike. Those are significant loads at very low speeds. That's not due to the tires but the whole system and how much frontal area you have but part of moving that bike down the road is pushing the air out of the way and any extra weight in the tires is extra power that you have to use to keep the momentum you constant as you force the bike through that air.

The difference in the air resistance of wide tires compared to skinny tires is inconsequential. Body position is the primary factor, and that isn't dictated by tire choice.

I, too, carry weight on a rear rack. It's not impossible to unload the rear wheel with weight on it. I go up and down curbs all the time. I carry the same load on a commute when I ride on the road as when I ride commute off-road and I've never had a problem lifting the rear wheel up and over curbs, rocks, or trail obstacles. Clipless pedals or toeclips help because you can loft a bike easier with your feet attached to the pedals.

I also ride loaded touring bikes both on- and off-road. Both have significantly heavier loads than my commuter bike and I'm still able to lift the rear wheel on the road touring bike over curbs and I can ride up- and downhill on road and trails. One problem I've found with wide tires (37mm) on a loaded touring bike is that they can't stand up to the weight requirements. I had to run a set of 37mm tires at 70 psi (4 bar) instead of the rated 90 psi (6 bar) to keep from blowing the tires off the rim. The extra touring weight (50 lb or 22 kg) was too much for the tires to hold onto the bead.

Rolling resistance of tires falls into a fairly narrow range of values. A wide road tire and a narrow racing tire (or even a wide racing tire) are going to have rolling resistances within 10% to 30% of each other. It's pretty insignificant. Once you go to a wide knobbed mountain bike tire, the rolling resistance doubles compared to a road tire but even they fall into a very narrow range.

6 bar (87 psi) is extremely low for a 23mm tire. That narrow of a tire is usually rated for closer to 8 to 8.5 bar...and it needs it. At 6 bar, the tire is too soft and doesn't have enough volume to cushion against impact. The tire bottoms out on the tube and pinch flats it. 6 bar is probably too low for a 28mm tire.

I run mountain bike tires at 45 psi (3.1 bar) and they are far from "bombproof", especially here in the US west where Tribulus terrestris are such a wide spread problem. Trust me, goatheads can go through just about any bicycle tire...even ones with protective belts.

Nope. Science is done via appropriate experimental design, validation, statistics, and peer review/replication.

The best skinnies don't come in size 28+.

How much faster are supple tires? | Off The Beaten Path

I'm willing to bet that if Heine tested michelin pros, tricomps, rubino pros and other similar tires he would find similar results...

You still have to move those heavier tires into the face of that wind resistance which takes energy. The gains in rolling resistance are tiny while the increase in pushing a heavier mass into the air is large.

Actually, the study found that rolling resistance matters more for everyday cycling than for racing, that it is a significant factor. And the difference in frontal area of a wide tire versus a skinny tire is small enough to be lost in the noise for the majority of us commuters who wear our normal clothes to get from point A to point B.

Actually it is impossible for riders who attach the load the rack, as with panniers. If one uses a backpack or similar bag, it is easy enough to unload the rear wheel, but many people prefer to not carry the weight on their bodies.

Heine: Some context for this "fatter is better" statement from someone who sells (and is a major proponent) of "fatties":

Tire Rolling Resistance - Roues Artisanales - Bike tech magasine - handbuilt wheels boutique

https://idata.over-blog.com/0/02/72/1...tubular-tn.gif

https://idata.over-blog.com/0/02/72/1...lincher-tn.gif

The experiment was properly designed and executed to answer the questions the researchers asked. That's how science is done.

If I recall correctly, the Bicycle Quarterly study measured the rolling resistance of tires going downhill. It did find that many fat tires rolled very nicely downhill with relatively low resistance. However, it did not account for the fact that cyclists don't always ride downhill. In fact, if you ride on hilly terrain, you spend much more time riding up hills than down them. This, to me, is the critical flaw in this study. In real life, most cyclists are riding up hills and accelerating from stops all the time -- and are thus slowed down by heavier tires, even if their rolling resistance is marginally better.

We get the idea that that you're going to keep repeating that a flawed experiment that proves that bikes that are heavily are pulled downhill faster by gravity is "properly designed", "science", "physics", etc. We get it, despite it not being any of those things.

Anyone who's used both knows that above the 23c-28c tire size range, a fatter tire gets slower on any regular decently maintained pavement.

I had a commuter bike with 26" wheels. Usual commute tire was a 1.5" slick. For the fun of it, I ran 2.5" Maxxis Hookworms, which weigh more per tire than some lightweight wheelsets. Super fun ride, but slower and I could definitely feel the weight. Better option was 2.35" Schwalbe Big Apples. Again, a better, fun ride, but without as much of the weight penalty as the hookworms. I still commute on bombproof 1.5" tires, but I wouldn't talk anyone out of wider tires.

Such questions are beyond the scope of that study. They sought only to analyze rolling resistance. Hills and stops do not affect that.

As far as weight is concerned, the standard deviation of the weight of my commuting cargo is more than the total weight of my tires. I doubt I'm unique in that respect. Weight matters for racers, but not so much for typical commuters.

The placebo effect works well with you, it seems. Science does not support your claim, either in theory or by experiment.

Weight matters as much more more than rolling resistance. I have been keeping records of all of my rides for many years and tens of thousands of miles, including average speeds, distances, times, bikes that I rode, etc. My data consistently show that my lighter bikes with narrower, lighter tires are faster than my heavier bikes with fatter tires. The average speed on my lightest bike is 2.5 mph faster than my heaviest bike. The correlation is almost linear, with speeds steadily increasing from my heaviest bike (touring) to my lighter cyclocross, sport touring and racing bikes.

I ride platform pedals. Bunny hopping a loaded bike with platforms is impossible for me. Not with the seat at correct height for riding.
Riding over 5 cm high kerbs is no problem with 37 or wider tyres, but with narrower, I need to slow down to avoid pinch flats - when the rear is loaded.

With clipless pedals? Or with platforms?

Yes, for really heavy, one needs fatter, like 42, or even wider.

6 bar is low for 23s, I had to be very careful to avoid pinch flats. But I found out it is low enough to avoid sharp objects like small sharp rocks, or pieces of broken glass to puncture tyre. 6 bars with 28s is just right for my weight. Fast and comfortable, without being too soft.

Goatheads yes. I was thinking of things in urban commute - broken glass, sharp rocks. For anything like thorns etc, one needs puncture resistant tyres like Marathons.


Something like this:

https://www.youtube.com/watch?v=kumLyiWkIoE

I like to be able to ride up those 5 to 10 cm heigh kerbs without slowing down too much.

Your data, as described by you, is useless for determining the effect of weight, because you're comparing different bikes. You've introduced too many confounding variables.

Weight doesn't matter for the typical commuter. Our weight varies by so much daily that the difference in tire weight is smaller than daily differences in load weight.

For others, weight doesn't matter as much as you seem to think. My cruising speeds on tour, with a bike+gear weight of 139 pounds, were very close to my cruising speeds on the same bike+commuting gear, weighing about 50-60 pounds.

And like I said, trolling seems to work well with you it seems.

Ah, a trolling accusation. It's the time honored tactic of people too proud to acknowledge that their assertion is unsupportable.