robertj298 

I keep reading about how wider tires are faster with less rolling resistance and I understand the
the concept but they always compare the two tires inflated to the same pressure. So is a wider
tire pumped up to 70 lbs. of pressure have less rolling resistance than a narrow tire pumped up
to 100 lbs. pressure?

ThermionicScott 

It's not even close to being that simple. Tire construction plays a huge role in a tire's rolling resistance, and the conversation needs to be clear whether we're just talking about frictional losses in the tire itself (true "rolling resistance"), or if the discussion includes losses in the rider's body as well (pick one of several popular terms like "suspension loss" or "impedance.")

sd5782 

The one takeaway I like from all the discussions seems to be that wider and softer isn’t necessarily a negative. Maybe and maybe not depending on many factors. That has given me license to be happy with panaracer 32s and 1 1/4s at 60-70psi and a more comfortable ride.

GhostRider62

The following is for tires. The impedance of various levels of blubber are unknown.


https://www.bicyclerollingresistance...parison#drop15

smd4

Guess that sums it up for me.

bamboobike4

I rarely, if ever, think about the ride or rolling resistance of any tire until I have a flat.
There's actually a chart somewhere that compares the rolling resistance of many tire models/widths.
Until I read it, I thought my Challenge 700x28's were really nice.
After reading it, I find myself riding them, anyway, but wondering if I'm wasting power.
If I'd never read the chart, I'd be fine, so I ignore the charts.

vespasianus

The road conditions also play a huge role in this. Compliance can help you go faster and be more comfortable.

SurferRosa

Just take an automobile tire atop a hill and let It go. It'll roll, gain speed and keep going. Now try that with a brand new folded 23mm bicycle tire. It might flop over once and then stop.

See, a simple experiment will tell you a lot about this sorta thing.

Andy_K 

This whole discussion is the result of a semi-genius way to create a new market that Jan Heine discovered. For years everyone assumed that wide tires (>32mm) were slow, and for the most part they were, really slow in fact, because they were mostly either mountain bike tires with a lot of tread (which flexes way too much on pavement) or city tires (which were made to be tough and durable and so are stiff).

The tires everyone who cared about squeezing the last Watt of performance out of were using were generally skinny, with 23mm eventually emerging as the typical size. But people who wanted to go fast on surfaces like cobblestones needed something with a bit more cushion, so you started to see 28mm tires with the same construction as their skinnier brethren. And guess what? They weren't slower.

So at some point Jan Heine and a few others started digging into this analytically, trying to find out how width and pressure relate to speed, and what they found out is that for tires with sufficiently supple casing and sidewalls there is essentially no limit to how wide a tire can be while still providing lower rolling resistance.

Now here's where I think Jan's semi-genius comes in. He fully believed the data before nearly anyone else did (accepted paradigms don't die without a fight) and seeing that there were essentially no tires on the market with the characteristics he wanted, he contracted to have them made. Then he went on an evangelism campaign telling people about the new understanding of tire width and rolling resistance. But when you understand it and understand that the tires need to be supple you look around and ask, "Where can I find 700x35/38/42 tires with smooth tread and supple casing?" Then Jan, and pretty much only Jan even now, says, "Well, since you asked...."

Some of the big manufacturers are starting to come around, and so you can get "race" tires from Continental, Schwalbe, and Vittoria as wide as 700x32, but still nothing wider. I guess it's still a small market.

rm -rf

From one of the many threads on this subject, a thread from 2018.

I posted this chart from Continental,comparing their GP4000 in different sizes.


See the yellow horizontal line, for example.
25mm at 6.5 bar/94 psi has a similar rolling resistance to the 28mm at approx 5.7 bar/84 psi.
And at the same pressures (a vertical line), larger tires have lower rolling resistance. But why do that!

As I commented then:
Rolling resistance tests aren't exactly the real world, often run on fairly small rollers with some kind of rough surface. Do they all apply to real world conditions?

But, here's one from a few years ago by Continental. For example, It shows 23mm at about 123 psi having the same rolling resistance as the 25mm at about 92 psi.

These are fairly small effects -- note the truncated scale on the Y axis. And it's kind of odd that the rolling resistance difference between 23 and 25 is larger than the difference between 25 and 28, even though the volume change is larger on the 25 vs 28.

vespasianus

Not sure when Jan started this thinking but larger and substantially heavier tires were shown to be faster and more comfortable in the MTB world many, many years ago (10+).

In my mind, the innovations in the bike industry are still coming from the MTB side of things.

ClydeClydeson

Something not clearly stated is that 'rolling resistance' (energy lost to the flex of the tire casing as it rotates) is only a small fraction of the total drag on a bike. At normal riding speeds (above ~20km/h) your total aerodynamic drag is vastly greater than drag from rolling resistance. As speed goes up, aero drag increases exponentially and rolling resistance only increases roughly linearly. Wider tires can have less rolling resistance, but wider tires can also cause greater aero drag, esp. if the tire and rim widths are not a good match. And same as total aero drag, aero drag from tires also goes up exponentially with speed.

Also, all other things being equal, wider tires are heavier and will slow you down when climbing.

'Suspension losses' were also mentioned above - energy lost to bike and rider being moved vertically by surface irregularities - and wider softer tires generally save you a few watts of this type.

ThermionicScott 

I feel the Mitsuboshi Trimline tire deserves an honorable mention in this story. It was one of the very few wide but not heavily-constructed tires still available when the VBQ crowd started trying old 650B bikes, and planted the seed for that whole thing, I think.

squirtdad

this is a problem IMHO in that form follows function and the function for mountain biking is hugely different than for road bikes. Flat bars are an example Tubeless is another example, for all the effort people put into tubeless, they could be on tubular with way less hassle. 1x systems is another

now get off my lawn you whipper snappers

Wildwood

I am not sure that Jan started the latest bruhahaha about rolling resistance, but anyway.... I nearly agree with all your statements, but have a problem with what is excerpted above.

sufficiently supple casing and sidewall - lacks specificity. Leads to everyone not riding Gatorskins or Marathon Plus, who paid more than $29.95 per tire believing they are riding 'sufficiently supple' tires.

essentially no limit to how wide - ....like out to my 48&50mm tires, and lacks the requirement any tire pressure input. Leads to everyone telling us their 'supple road 48s' - which they run at 35 psi, and supports fenders, lights, racks, and partially loaded panniers - delivers lower rolling resistance than a 28mm VeloFlex (for an example) tubular @ 110 on an SLX framed bike with only one bottle bracket and not 1 eyelet, carrying only a small tool kit.

and when you laugh in their face, they retort with, well my ride is more comfortable so I can finish sooner or fresher,...... or some such nonsense.

Then they ride off, sitting bolt Petersen upright, with baggy shorts and MUSA cotton shirt, forgetting that wind resistance is vastly a greater contributor than rolling resistance. Smug that Jan's facts always win the day.

Then there is the road/off road complication. And some folks want flat free tires, so how much sealant?, in those lightweight tubeless with supple sidewalls and casings.


In the end, as long as everybody's happy with their ride; whether 1/2 of us are full of somebody's Kool-Aid, it just don't matter - unless you are racing for a living.

facts or alternate facts - smile while you go.

YMMV

Andy_K 

Things are substantially more complicated when you start talking about MTBs. The typical engineering simplification/assumption of a basically smooth surface to ride on goes away completely and so the lab rolling resistance tests also become meaningless. I was never into mountain biking, but I vividly remember when I did my first cyclocross race with my tires pumped up to the max psi they would take. That sucked. Afterwards some kind soul suggested that I try closer to the minimum psi they would take, and holy cow that makes a difference. But you can't just put MTB tires on a road bike and make it faster, so there was a lot of work to be done to translate the benefits.

Speaking of MTB driving innovation, did you see this year's Milan San Remo result? The winner attributed his victory to using a dropper seat post.

Andy_K 

Yeah, that lack of specificity is the crux of this whole thing. Besides the retort about staying fresher, it leaves open the explanation that the reason you didn't find it to be true when you tried wide tires was that they weren't sufficiently supple. But the reason I used that term is as a shorthand for an explanation so long that no one would read it and I'd probably get the details wrong.

vespasianus

I did. Pretty cool to see that.

No, you can't just put a MTB tire on a road bike and make it faster. Tires need to be specific to the terrain. When I head to the mountains, I generally switch tires.

A great Ritchey invention was his development of a tire just for riding in Moab. Moab has no dirt, just rock - and gravel roads. So he made what was basically a sticky slick tire for use in Moab and for riding on the gravel roads around the trails. In some was, that was the first gravel bike tire!

nlerner

In regard to the first gravel tire, I think likely something from Dunlop:

Wildwood

@Andy_K - Caught me red-handed - I have never purchased a supple tire wider than 30mm. And I have never scientifically conducted a test of rolling resistance.

I consider rolling resistance a secondary consideration compared to a quality ride with good flat protection. Personally, that translates to good tubulars 22-28mm for pavement bikes that see packed 'gravel' regularly. Wheel weight at the rim is valued on hilly roads or mountain climbs, not as much as gearing, but more than rolling resistance. Has anyone measured airflow of a 42mm front tire compared to a 28mm to see if any 'rolling resistance advantage' is negated by aerodynamic disadvantages? At say, 18mph.

For a purely gravel ride the tire width should be commensurate with the size of the gravel, regardless of the rolling resistance. Right? Like riding over the underdeveloped road to the Oregon Coast??? If I remember the thread the best tire size for the worst section would have been 3" fat bike tires. Not the whole route by even a tiny fraction, but on a 100mi road route with some light packed gravel for 5mi = Do you ride 44mm tires or 28s? No right or wrong, just preference.

As stated before the RR issue is really more of a pissing contest than performance concern for all but the most serious pavement racing crowd and track riders.

So everybody just ride whatever makes you happy, and smile.

YMMV, and likely does. Makes for a better cycling marketplace.

smd4

If the marketplace is better, can you let me know where I can get some 700x19 skinwall slicks?

Wildwood

NEW VITTORIA CORSA CX 19 TUBULAR 700 NOS | eBay
Took but a second.
The marketplace has moved beyond 19mm -

smd4

Not *all* of the marketplace. Those aren't slicks, anyway.

My bad for not specifying clinchers.

If they still make all-white Model T tires, I should be able to get 700x19 slick clinchers for my classic bike.

billridesbikes

The first 'Bicycle Quarterly' article that I recall addressed tire width and pressure was from the August 2009 'Minimizing Suspension Losses'. "Wider tires run at lower pressures are very effective in reducing suspension losses .... Further testing is required to determine whether the added width or the reduced pressure are more important". pp9 I remember this article being a kind of epiphany for me and replaced my tires with 25mm ones with lower pressure that season. Within my own cycling group I think I was in a small minority running wider on the road at that point. So Jan's been thinking about this for at least 13 years.

But if you want to trace this back even further you can go back to Archibald Sharp's "Bicycles and Tricycles" 1896, which has comparisons of rolling resistance of various tire widths (although no pressures are given) and a discussion of suspension losses from tires where Sharp though up to 12% of energy was lost due to suspension loss on bikes with solid rubber tires. So the bicycle tire issue as been around for 125 years or more. Nothing new under the sun.

Andy_K 

This I completely agree with, and I suspect the vast majority of people here would also. I don't actually care at all which tire is faster. I care which tire doesn't make me feel like I'm pedaling through thick mud. That usually corresponds to the "faster" tire. Flat protection is a sliding scale. When I ride a bike to work, I use a lot of bike lanes which tend to collect ridiculous amounts of debris. In those conditions I tend to use thicker tires that I wouldn't enjoy for a recreational ride. But for recreational rides, I can tolerate less flat protection. BTW, wider tires at low pressures are also less prone to punctures.


I'm sure someone has. I don't know the answer. At 18 mph, I'd be surprised if it's a significant effect. At 30 mph, it probably is. In both cases, it's probably on the order of things that would cost you a handful of seconds in a time trial.


Yeah, so this is the other place where the good news of wide tires being fast is useful information. If I'm riding on gravel, I'd like to have a wider tire, but if the gravel is a small portion of the route I'm riding, I don't want to sacrifice enjoyment of the paved miles just for a short gravel segment. But if I have wide tires that roll well on pavement, I don't have to.