Jan Heine's 12 Myths in Cycling: #1 Wider tyres are slower

[Thoglette]

Iconoclast; all-road randonneur; owner of Bicycle Quarterly & Compass Bicycles; and fearless self promoter Jan Heine is running a series of blog posts on cycling myths.

He's a way in and so far it's mostly sane. Given I've seen three or for questions on some of these topics this year I thought it'd be worth adding some links to them.

Myth #1: Wider Tires Are Slower

For almost a century, cyclists ‘knew’ that narrower tires roll faster. Some people realized that in theory, wider tires are faster due to their shorter contact patch, which deforms less as they roll. But the thinking was that in practice, the lower pressure at which wider tires must run limited their performance. If you wanted to go fast, you chose narrow tires.
That is what we thought when we started testing tires almost 12 years ago.....

[andrewjcw]

Cool article, look forward to the others.

One of the most interesting things that the article didn't touch on was the very slow reaction from the world tour and pros in general to switch to the wider tyres, even after all the evidence was out that they were objectively better.

[g-boaf]

Cool article, look forward to the others.

One of the most interesting things that the article didn't touch on was the very slow reaction from the world tour and pros in general to switch to the wider tyres, even after all the evidence was out that they were objectively better.

I've tried wider tyres on all sorts of road surfaces and cycleways and I find them no faster than 23mm. Moving to 25 or 28mm isn't just some magic thing that gives you a big boost in speed. 25mm is more comfortable, but it seems the same for speed.

However, this "slow reaction" is also another myth, as some teams have used wider tyres where they were suitable.

[hamishm]

I've tried wider tyres on all sorts of road surfaces and cycleways and I find them no faster than 23mm. Moving to 25 or 28mm isn't just some magic thing that gives you a big boost in speed. 25mm is more comfortable, but it seems the same for speed.

The article only claims that wider tyres are faster on rough roads, and otherwise the same speed but not slower than narrower tyres. Your experience doesn't seem to contradict that.

[Ross]

A lot of opinion in that article but not much actual science.

[RonK]

"fearless self promoter" Yes this describes Jan Heine exactly.

His apparently myth-busting claims and pseudo-science about tyres (and other topics) and simply are self-serving marketing aimed at promoting and selling his own particular brand of Compass Tyres.

And of course, about selling Bicycle Quarterly magazine.

[Duck!]

There is more to a tyre's speed than its width. "Wider is faster" may hold true, but only if you're comparing different sizes of the same model tyre. Otherwise you might as well be comparing apples with rocks.

[g-boaf]

I've tried wider tyres on all sorts of road surfaces and cycleways and I find them no faster than 23mm. Moving to 25 or 28mm isn't just some magic thing that gives you a big boost in speed. 25mm is more comfortable, but it seems the same for speed.

The article only claims that wider tyres are faster on rough roads, and otherwise the same speed but not slower than narrower tyres. Your experience doesn't seem to contradict that.

Well I frequently ride on a rough road and even with the same type of tyre (just wider) there is no difference. The wider tyre isn't faster.

[biker jk]

I've tried wider tyres on all sorts of road surfaces and cycleways and I find them no faster than 23mm. Moving to 25 or 28mm isn't just some magic thing that gives you a big boost in speed. 25mm is more comfortable, but it seems the same for speed.

The article only claims that wider tyres are faster on rough roads, and otherwise the same speed but not slower than narrower tyres. Your experience doesn't seem to contradict that.

Well I frequently ride on a rough road and even with the same type of tyre (just wider) there is no difference. The wider tyre isn't faster.

At the same pressure the CRR of a 25mm tyre is around 12% lower than a 23mm equivalent (see Mavic article below). At 250 watts, this would make you around 0.25kmh faster which would be imperceptible.

http://engineerstalk.mavic.com/en/the-r ... rim-width/

Admittedly, at average speeds above 35kmh, wheel aerodynamics become more important than tyre rolling resistance, so a narrower tyre might be faster, especially if the wider tyre exceeds the width of your rim.

[singlespeedscott]

Jan is not saying that wide tyres are faster. He saying that wide tyres are no slower than 23mm tyres on a smooth surface. It is when the surface gets rougher that you see improvements in speed for wider tyres over narrower ones.

I know from personnel experience that my times on dirt roads are way faster on 32mm tyres than they where on 23mm tyres, even though I am not as fit as I was 15 years ago.

And not all wide tyres are as fast as narrow tyres.

The speed only remains the same if they use the same casing design. A supple tyre is the key. And no its no all about TPI of the casing. You can have a supple tyre with low TPI and a stiff tyre with high TPI. If your 32mm tyre uses the same casing as your 23mm tyre your effort at a steady pace on a smooth surface will be identical.

[find_bruce]

I misread the title - I thought it was about the 12 myths being perpetuated by Jan. Sadly I don't see him as the myth buster type

[Thoglette]

However, this "slow reaction" is also another myth, as some teams have used wider tyres where they were suitable.

As someone who's been on the wide tyre bandwagon (for practical reasons, not speed) for over a decade, the biggest problem with "modern" bikes is that the frames and brake components won't take much more than 25mm. Which is fat compared to the 19mm tyres I rode a decade or more ago but still narrow v.s. the 32mm I'm using today. Zipp, Challenge and a few others are producing wider race tyres (i.e. hand built tubulars and open tubulars) but still maxing out around 30mm.

[uart]

At the same pressure the CRR of a 25mm tyre is around 12% lower than a 23mm equivalent (see Mavic article below).

Yes but it just isn't a valid comparison to compare tyres of different width at the same pressure.

At the same pressure wider tyres inherently have to support a greater tensile force at the bead without getting blown off! For the same construction and materials the wider tyre can safely support less pressure. Also at the same pressure the wider tyre will actually be less comfortable, as it requires less deflection to achieve the same contact patch and hence bear the same load.

Different widths and same pressure just isn't and apples to apples comparison.

[Thoglette]

At the same pressure the CRR of a 25mm tyre is around 12% lower than a 23mm equivalent (see Mavic article below). At 250 watts, this would make you around 0.25kmh faster which would be imperceptible.

http://engineerstalk.mavic.com/en/the-r ... rim-width/

That article is, shall we say "old school" in that their CRR chart is now discredited.

Old view vs New understanding from Zipp's founder
Joshua Poertner on Tyres (http://trstriathlon.com JIM GOURLEY JUNE 6, 2016)

It gets better. A graph from a little later on in the article

[biker jk]

At the same pressure the CRR of a 25mm tyre is around 12% lower than a 23mm equivalent (see Mavic article below).

Yes but it just isn't a valid comparison to compare tyres of different width at the same pressure.

At the same pressure wider tyres inherently have to support a greater tensile force at the bead without getting blown off! For the same construction and materials the wider tyre can safely support less pressure. Also at the same pressure the wider tyre will actually be less comfortable, as it requires less deflection to achieve the same contact patch and hence bear the same load.

Different widths and same pressure just isn't and apples to apples comparison.

If you're not worried about comfort it's a valid comparison. Of course most are and will run lower pressure but drop it more than 20psi or so and you won't be faster with the wider tyre. That's fine for most as well.

[singlespeedscott]

Well Tour magazine seems to like Jan's tyres, and they didnt even use one with a supple casing -

https://janheine.wordpress.com/?mc_cid= ... 4fe93d418a

[hamishm]

Well Tour magazine seems to like Jan's tyres, and they didnt even use one with a supple casing -

https://janheine.wordpress.com/?mc_cid= ... 4fe93d418a

Well the standard casing is supposedly still supple, just not as much as the extralight.

They put 6 bar / 87 psi in the 35mm tyre though?! Youch. And 7 bar / 100 psi in the 25mm GP 4000 also.

[uart]

That article is, shall we say "old school" in that their CRR chart is now discredited.

Old view vs New understanding from Zipp's founder
Joshua Poertner on Tyres (http://trstriathlon.com JIM GOURLEY JUNE 6, 2016)

It gets better. A graph from a little later on in the article

It would be nice if they included some images of those surfaces so that we could get a better idea of exactly where the "breakpoints" are. Just exactly how rough is "coarse intermediate asphalt"? And what exactly is "machined roughened concrete" and how rough is it?

[Thoglette]

It would be nice if they included some images of those surfaces so that we could get a better idea of exactly where the "breakpoints" are. Just exactly how rough is "coarse intermediate asphalt"? And what exactly is "machined roughened concrete" and how rough is it?

There were some descriptions in the article of the machine roughened concrete. 8mm IIRC. I know what smooth asphalt is.

But I don't see much of it - mostly it's small stones or chip seal over a cracked base.

[g-boaf]

It would be nice if they included some images of those surfaces so that we could get a better idea of exactly where the "breakpoints" are. Just exactly how rough is "coarse intermediate asphalt"? And what exactly is "machined roughened concrete" and how rough is it?

There were some descriptions in the article of the machine roughened concrete. 8mm IIRC. I know what smooth asphalt is.

But I don't see much of it - mostly it's small stones or chip seal over a cracked base.

One of the roads I use has this same chip seal over a patchy, rough base. It's a really nasty surface. It's not hugely rough, you just get a lot of buzz through the bars - and I'm riding a pretty comfortable bike. I'm still doing pretty high speeds on it regardless of tyre width.

Still, could be worse and be like those cobblestones I've ridden on. They were the squarish type but they were still quite rough on 25mm tyres. At least there weren't any gigantic ruts between them. First time I've encountered them and luckily not in the rain.

[uart]

One of the roads I use has this same chip seal over a patchy, rough base. It's a really nasty surface. It's not hugely rough, you just get a lot of buzz through the bars - and I'm riding a pretty comfortable bike. I'm still doing pretty high speeds on it regardless of tyre width.

I think that a lot of the non main roads that I ride on would probably be classified as coarse asphalt. Mostly I have no problems with that level of roughness, and don't really feel it slowing me down too much. Occasionally however you do come across a real "bogey" road where it seems to disproportionately suck the energy out of you. I know other riders have mentioned the same thing, saying things like: "oh that road section! Yea it's only 5km but it feels like about 15" and so on.

Here's one for example that I sometimes ride and it noticeably zaps your kinetic energy (particularly the edges in the cycle/breakdown lane).
https://www.google.com.au/maps/(AT)-33.004 ... 6656?hl=en

[warthog1]

Admittedly, at average speeds above 35kmh, wheel aerodynamics become more important than tyre rolling resistance, so a narrower tyre might be faster, especially if the wider tyre exceeds the width of your rim.

Agree.
Either way, the difference is stuff all.
Ride what you like or what fits your bike.
It isn't about to turn any of us into a more competitive rider.

[Alex Simmons/RST]

There is more than just Crr involved when it comes to the resistance forces in play. Tyre aerodynamics is also a factor and that's impacted by a few things. Unless any analysis or testing considers all the forces in play and uses robust testing methodology, it's not giving the full story and may well be misleading.

Yes this sort of stuff is in the 1%rs which for most isn't relevant when compared to other tyre choice factors such as comfort, puncture resistance, durability etc but when you race and the differences are slim, it all matters.

[g-boaf]

Admittedly, at average speeds above 35kmh, wheel aerodynamics become more important than tyre rolling resistance, so a narrower tyre might be faster, especially if the wider tyre exceeds the width of your rim.

Agree.
Either way, the difference is stuff all.
Ride what you like or what fits your bike.
It isn't about to turn any of us into a more competitive rider.

I didn't find a lot of difference at all between the 25mm and 23mm Continental GP4000S II tyres, they seemed about the same. But having switched over just by chance to the Specialized S-Works Turbo 26C tyres. Second ride on them today, they feel a lot more grippy through corners and they seem to roll well. I was sitting on a 35km/h average tonight (rolling hills and some gusty headwinds at times). Over a very poorly surfaced section of road (really coarse surface) they seemed a little bit more comfortable than 23mm Continental, but not massively so.

They are indeed pretty nice tyres.

[warthog1]

There is more than just Crr involved when it comes to the resistance forces in play. Tyre aerodynamics is also a factor and that's impacted by a few things. Unless any analysis or testing considers all the forces in play and uses robust testing methodology, it's not giving the full story and may well be misleading.

Yes this sort of stuff is in the 1%rs which for most isn't relevant when compared to other tyre choice factors such as comfort, puncture resistance, durability etc but when you race and the differences are slim, it all matters.

Thankyou Alex. We need more input from you to sort the poo from the clay