[Closed] Any "real world" tests of properly wide road tyres?

The trouble with real world tests is there are too many variables.

A 50mm tyre might be faster on a rough bit of road, but is going to be slower on smooth roads simply by virtue of having more than doubled the aerodynamic drag. So it becomes subjective, do you want to go faster or more comfortably? Which isnt going to be something a simple test can tell you.

I.e. you could probably optimise a bike arround 25 or 28mm tyre and find its faster in some conditions, but you wouldnt put 32mm tyres on a bike for racing on the road. But you might put them on your sunday clubrun bike if your fit enough to overcome their drawbacks and keep up.

I suspect there are also speed variables in this ie at one speed the wide tyre is better, at another the narrow one.

Surely that’s why you need a real world test though. I can see that a wider tyre has more aerodynamic drag in theory but I have no idea whether that actually matters out on the road at the speeds I ride. Bicycle “science” seems to be full of accepted wisdom with very little evidence to back it up.

I agree that it’s hard and most tests don’t come close to being scientifically rigorous but some are better than others.

Rule of thumb, the faster your average speed the narrower a tyre you should run as the aero benefits outweigh the reduced rolling resistance.

Hence why the pro peloton arent all on 32c's if it was proven to be faster they 100% would be.

Yes, but if I tested a tyre down the new bypass Id bet my bike on it that a 23mm tyre is quicker as its like a billiard table.

Down the old cycle path running parallel to it then Surly E.T.s would win simply by virtue of getting through without a puncture.

Remember for a comparable tyre rolling resistance is the same for the same comfort level (i.e. lower pressure in a big tyre). A wider tyre is faster at the same pressure but only by about 1W between 23mm and 32mm.

The difference between a shallow and 50mm rim is about 12W (for a pair) at 30km/h.

I cant find a figure for the total aero drag of a 23mm tyre and wheel, but its going to be of the order of 10-50w i imagine, and doubling the frontal area is double the drag so that 1W saving in rolling resistance is completely dwarfed.

If you want a "real world" test go an do it yourself as the real world is the world as you experience it.
I have a few loops I do that I have done a lot of times over the last few years and my times vary so much (even on the exact same bike, tyres etc,.) that any difference in times with different tyres were not prove anything. That is why a scientific test would be better but that would be a number of tests on specific terrain for specific distances and gradients so again when riding 50 miles and encountering the different terrain, gradients, wind speed etc,. in the real world you may not match up with what the scientific tests would suggest.

I am currently riding 23c tyres because I like how they feel...

Bicycle “science”

Is largely marketing.

the aero benefits outweigh the reduced rolling resistance

Daft question, have you got a link to anything which proves the RR benefits of wider tyres at proper pressure? I've seen plenty of "studies" which show that a 23 run at 50 psi is crap. I've not seen anything that shows a 28 is better than a 23 at 100psi.
No argument here that lower pressure is more comfortable (which might be faster as a result of fatigue etc) but the RR thing seems largely to be reliant on running skinny tyres at inappropriately low pressures. (and often different tyres and carcasses too)
(I've never seen anything testing wider tyres at a range of pressures either, certainly my wider tyres at 80psi feel much better rolling than they do at 50 but I'm not sure the comfort benefits exist at 80 because the tyre feels that much more firm than a narrow one at 80.)

As to the op, I can provide RW opinions of my 23s vs 32s, vs 42s vs 2.35s but, they're all different tyres so of no real scientific value (the 23s are on a different bike too). One thing which is constant is they all feel quicker at higher end of acceptable range pressure than mid range or low.

At the same deflection all widths roll the same. I commuted today on 32c, rode 100 k on 23c on Sunday and did a 12 hr TT recently on 20c (ok it has three wheels). Comfort is better on bigger tyres at lower pressures. But for speed, my 20c on 3x HED3 carbon wheels is the fastest and most aero.

I see little benefit once you get above 25c. Tyre quality is a bigger factor. I’m 69 kg. Heavier riders may want a higher pressure.

BTW I have GP4000 in 20/23/25c and GP5000 in 23/25c for reference on different bikes and wheel sets.

Narrow tyres on a wider profile rim give a wider profile, e.g. a 23mm on a 28mm internal rim width will come out at 26mm (Cannondale SystemSix).

OP, check out Jan Heine and Bicycle Quarterly for the gospel about wider tyres

Once you're travelling above ~15mph, aero losses play an incresingly important role, especially at the front end of the bike for factors including how the front tyre shape "blends" into the front wheel rim sides.

For a compromise of speed vs comfort on my 17mm internal rim width wheels on my road bike, I should probably go ~23mm (real world measurement) up front and 32mm at the rear (if I could just about safely squeeze them in, 28mm GP4000S IIs are ~31mm wide).

I swapped out my fatbike's fat rear wheel with 26x4" JJ back to FatNotFat 29er with 700x28 Grand Sport Race on Monday. This reduced the weight by ~1.9Kg and the rolling resistance by a guess of ~7W, but even at ~12mph the ride home with ~350feet of climbing polarised towards the end of the ~4.5 mile commute felt much less hard work... Depsite having a 29x2.35" G One Speed Evo up front.

I’ve not seen anything that shows a 28 is better than a 23 at 100psi.

but you'd never be running a 28 at 100PSI, that would be defeating the purpose of the larger tyre

Daft question, have you got a link to anything which proves the RR benefits of wider tyres at proper pressure? I’ve seen plenty of “studies” which show that a 23 run at 50 psi is crap. I’ve not seen anything that shows a 28 is better than a 23 at 100psi.

Have a look at the gp5000 test on bicycle rolling resistance .com. its probably the only tyre they've tested from 23mm to 32mm. And they test them at, the same pressures, the recommended pressure and equal deflection. The biggest difference is about 1W, it's tiny really.

Bicycle quarterly kicked off the whole wide tyres are fast thing, but then the owner owns compass tyres IIRC.....

I dont dispute that there are benfits, but outright speed on the road isnt one of them unless your road is truly bad enough that suspension plays a part. If you want to ride a 200k audax, 28c tyres might make it more confortable. If you want to do a 200k race, 700x25.

Is largely marketing.

There are a few people trying to be (at least a bit) scientific about things. Whether that is peer-reviewed work in journals or just trying to devise a test that isn't too biased and approaching the question with an open mind. But you are right, the vast majority of tests you find online are really just thinly disguised marketing. You want to buy a new bike, but find it hard to justify (to yourself or whoever)? No problem, here is an article/video that "proves" your new bike will be better. It does no such thing of course and usually doesn't even pretend. But as long as you realise it's only there to help the economy keep ticking over that's fine.

If you want a “real world” test go an do it yourself as the real world is the world as you experience it.

That's true, but a) it would mean buying a load of tyres, wheels and probably frames to accommodate them anb b) I'm lazy and it is much easier to sit here and criticise somebody else's test rather try to devise my own for other people to criticise.

OP, check out Jan Heine and Bicycle Quarterly for the gospel about wider tyres

It was reading those articles that started this thread 🙂 But I've still not found many actual tests that go beyond 28mm. I'll look again though.

info from jan heine here on wider tyres

Doh...too late

And they test them at, the same pressures, the recommended pressure and equal deflection.

Ah I'll dig that up ta.

The biggest difference is about 1W, it’s tiny really.

Speak for yourself, that's like 50% upgrade...

but you’d never be running a 28 at 100PSI, that would be defeating the purpose of the larger tyre

I'd be much more inclined to run 28s at 100psi than 23s at 60psi but regardless this is sort of my point, most everything I've seen relys on running the wrong tyre at the wrong pressure. (Tinas' article doesn't count as I've not read it yet and, even then, it's one in a myriad of things)

Then tyre makers go and ruin it all by having completely different ideas about what a 25c tyre atually is. Or 28c or whatever.

My Michelin Pro4 25c are just about as wide as the identical tyres in 28c on another bike, jjust the 28c is taller. Vittorias 25c on another wheel (identical rim) is 3 or 4mm narrower, so even if you decide you want, say 25c tyres, there's no guarantee you're going to get the benefits anyway.

TINAS' article

Interesting there's more of a difference from the tube type than the width or the [sensible variation in] pressure. At "recommended" pressure there is marginal RR difference between 32s and 23s,the 23s being lower resistance but the wider tyre has a lower RR for any given pressure - 32s need to be at 100psi to have lower RR than 23s at (appropriate for the size) 120psi.

That’s true, but a) it would mean buying a load of tyres, wheels and probably frames to accommodate them anb b) I’m lazy and it is much easier to sit here and criticise somebody else’s test rather try to devise my own for other people to criticise.

I have bought a load of tyres over the years and recently switched from 28c to 23c (same model of tyre). The 23c is faster uphill. I also did a comparison 2 years ago (again with same model of tyre) between 43c and 38c. The 38c tyre was faster (on road and gravel)

The tests were various Strava segments where I was going as fast as I could.

Again, if you really want to know you will need to make your own comparisons as you may not find what I found due to you being heavier/lighter, riding on different roads and different gradients and at different speeds.

I had 42mm voyagers on my commuter. They were shit (draggy). Got 30/32 spesh roubaixses now, they're better and still comfy even on rough Cumbrian lanes, not up to much off road though.

25mm tyres are faster than 30mm according to me and this improvement in fastness goes up when riding in a group thats faster, but I prefer 28mm tyres which are still fast with some comfort and befote you ask yes i r scientist.

Might have popped some GP5000's in a 32 on my commuter last night 🙂

Still to early to pass judgement but 32's def slower to spin up than schwalbe ones in 25 and def a noticeable change in steering feel as expected but not soul destroyingly slow once rolling and the extra grip/comfort is very nice for the winter months as the roads around here fall apart.

Got some 47 Horizons on 650b on the fun bike and they are suprisingly quick but I think the novelty runs out if you were commuting any distance on em on normal roads but great if your mixing your surfaces up.

In my experience wider lower pressure tyres are much slower but much more comfortable. My winter bike has 42mm Contact Sports (lovely tyres) and running low pressure is like sitting in an arm chair but bloody hard work. My commuting bike has 32mm tyres and is quicker but less comfortable, my 'summer' bike has 23mm tyres and is quicker again (you have to factor in the difference in weight as well).

In the '80s I used to TT on 18mm tyres pumped up 'as hard as they would go'. It would be interesting to ride a bike with a variety of tyres and pressures on the same road to see what the difference would be. The problem is that you can never recreate the same conditions and that lab rolling resistances only tell part of the story.

yes i r scientist

Botanist?

I have ridden the same bike on 22mm tubs, 25 mm and 28mm contis. I cannot tell a difference apart from the gp4000s are far grippier and that for me trumps everything

the only difference I can tell is if the pressures drop they feel significantly slower.

My best road bike has 23s, my allroad I either ride with 650b 48 or 700c 32.
The road bike is fast at 85/90psi, the 650b48’s are long distance good and the 700c32’s are good compromise fast.
I did run 650b38 but found the gearing too low.

I don't ride road bikes but have done and there are a few in our household.
Tyres seem to have settled on 25mm width for (perception or other wise) comfort and efficiency.

Maybe one reason they don't test anything wider with any conviction is because most road frames that are built for speed won't take anything much wider, I know my OHs bikes won't.

Therefore, seems a tad daft wasting time to prove a 42mm tyre may well be the be all and end all to find 90% of the people who could benefit from it can't fit it on their bike.

Therefore, seems a tad daft wasting time to prove a 42mm tyre may well be the be all and end all to find 90% of the people who could benefit from it can’t fit it on their bike.

Plus it is very, very unlikely to be faster. It will weigh more and it will be less aerodynamic. Unless the roads are very rough the 42 will not give anything over a 28.

30s at 60 psi tubeless here. I don’t race or do fast chain gangy stuff so speed is not important, faster or slower. Its great on crappy roads and cornering. I can barely get my crappy track pump to 100 psi anyway.

I am currently riding 23c tyres because I like how they feel…

One thing which is constant is they all feel quicker at higher end of acceptable range pressure than mid range or low.

This is covered in some of the wider/balloon tyre write ups. people "know" skinny tyres at high pressures are the fastest, and with that comes with harsh/direct ride feel, so they associate harsh/direct ride feel with a tyre being fast, and "know" a more comfortable, less buzzy ride will be slower, and won't like it.

Whether it's actually quicker or not doesn't really come into it!

There was another article on a similar theme someone posted a feew weeks back about long term bikes testing with blinded riders. Almost all opinions about how a bike rode or how quick it was were pre-formed by what sort of bike it looked like.

Whether it’s actually quicker or not doesn’t really come into it!

Well in the interest of scyunse I put 65psi front and rear in my 42s this morning. Much more noticeable over rougher tarmac, more jarring but I wouldn't say uncomfortable, that said it's a road, even the "path" is only so rough and then it's mostly easily avoided in all but short sections.

On those rough bits I was definitely slower by virtue of using my arms and legs to absorb the impact so pedaling les, even if I was only half my normal speed over those bits though that's maybe a minute max extra over 35 minutes of riding. On cobbles it might be different but actual roads mostly aren't bad enough for there to be any real benefit IMHO.

I was, in total, 3.5 minutes quicker than average for my morning commute this morning though and traffic seemed as bad as usual. So on that basis:
3.5mins faster than 35min average means 65psi is roughly 10% more betterer than 50psi

Thanks for all the responses. It looks as though the simple answers to my question is "no, there aren't any real world tests of tyres above around 30mm that could count as even vaguely scientific". Lots of received wisdom that doesn't seem to have any actual evidence to back it up. I guess that's pretty much the definition of received wisdom.

I hear comments to the effect that a wider tyre will be slower because it's heavier or less aerodynamic, which sounds fair enough, but I'd still like to see the proof.

Lots of anecdotal stuff of course, which is almost the raison d'être for discussion boards like this. All very interesting but most of it doesn't stand up to much scrutiny (different tyres on different bikes under different conditions are different)

The one that interests me (particularly in light of the test done on tank seats by the army, which showed that a human body can easily absorb more power that a top cyclist can generate) is the idea that wider may be more comfortable but narrower is still faster. This seems to assume that discomfort is just something to endure and the only negative effect is on long term endurance of the rider. But is this true? What is discomfort? Is it just the body's way of telling you that heat is being generated somewhere? If so, that discomfort isn't just annoying it's actually lost energy that would affect your speed.

I'm not saying a 40mm tyres is faster than a 25mm one, but I'm not saying it's not either. I'd like to see a well designed study that tried to answer the question. It sounds as though there isn't one though, so we can just continue to argue the toss until someone does one 🙂

the only difference I can tell is if the pressures drop they feel significantly slower.

Completely non scientific I know, but after listening to that podcast, I've stopped pumping up my road bike tyres completely. I used to religiously put 120psi in each morning before a ride. Other than the loss of road buzz, and smoother ride, I've not noticed any excess loss when riding in a fast group. No idea what pressure they're at now, probably about 60 maybe (25mm GP4000s). I intend to continue the experiment until I start hitting rims on the tyre, at which point I'll put some air in them...

Thanks for all the responses. It looks as though the simple answers to my question is “no, there aren’t any real world tests of tyres above around 30mm that could count as even vaguely scientific”.

A real world test will never be scientific. A real world test would be me riding around a 20 mile loop using different tyres each time. However, during that loop the wind speed and direction will differ and the exact bits of road I ride on will differ. As my times around that loop already differ by up to 5 minutes with no change of tyre so any changes from a tyre are going to be impossible to claim.
To narrow it down a but I can pick a segment on strava and repeat that with different tyres. As said, I have done that. 23c was faster uphill, 38c was faster on gravel.

That is as scientific as a real world test will be.

Botanist?

I prefer plant community ecologist!!

A real world test will never be scientific.

That's going to upset a lot of scientists 🙂

That is as scientific as a real world test will be.

Are you sure? How about (as a starting point) a group of riders with power meters and GPS devices riding the same segment multiple times, swapping wheels between each run, on a day when the conditions were stable. That should give you data on the power required to maintain a certain speed with different tyres (on that particular segment, under those conditions). As long as you do enough runs and you can get tyres of the same construction in the different sizes. you should be able to tell whether tyre size is a significant factor or not. You could also test whether time of day was a significant factor to see if the conditions changed significantly.

It's not that hard to design real world tests. Scientists do it all the time. You don't have to remove variability, you just need to ensure that there isn't a systematic bias. If there is too much variability for any of the factors to be statistically significant that's fine. It's still scientific, it's just inconclusive. The conclusion of most scientific studies is usually "more studies required (please send money)" anyway.

I can pick plenty of holes in my own study design above, but I still think it's possible to design a scientifically valid real world study. Just avoid the technique beloved of GCN, GMBN and many others of designing "experiments" specifically to highlight differences that you've already concluded are there 🙂

Not necessarily what you are asking, but there is enough information around which infers to me what the fastest tyre size is. Plenty of scientific information about, both Zipp and Enve have had reports about the fastest tyres on their wheels. Reynolds, while I've not found a report - just individual statements. They don't go to the 50mm tyre size, but they don't need to. Google the 105% rule to find more information.

https://blog.silca.cc/part-5-tire-pressure-and-aerodynamics

I also don't really find the infomercials from Bicycle Weekly / Compass very useful. The word "probably" comes up a couple of times, narrower tyres are probably faster in certain conditions etc. Also, as an inference, I look at the fact that the Pro-Peloton are not riding wide tyres. There is a culture in pro and amateur cycling to look at the most marginal of gains possible. If 32 or 35mm on the current frames and wheels available was fastest, pretty sure we would see them at the start line.

I ride 23mm front and 25mm back on my race bike and 32mm front and back on my winter/training bike. Different compounds so impossible to say if its the tyre size - but I am slower on the wider tyres (on the same rim).

I can pick plenty of holes in my own study design above, but I still think it’s possible to design a scientifically valid real world study.

Yes, you are probably right. Maybe by literal reading of the term "real world"
My real world is riding mixed terrain all year around. On some sections a wider tyre is better and on other sections a narrow tyre is better. Doesn't really matter what someone else has tested with power meters etc,. as they are not riding the same mix that I am so it makes no difference to my real world as I am not going to be switching tyres half way around, dependent on what route I fancy half way around etc,.

Ah, right, fair enough. I think I see what you mean and I agree. Any test that is remotely scientific is probably going to have to be limited to a very specific set of conditions (e.g. single segment of track). It may still be a real world example but isn't necessarily going to tell you what is best for you over a whole ride.

You don’t have to remove variability, you just need to ensure that there isn’t a systematic bias.

And repeat it, a lot.

And then some more 🙂

I can't think of a reasonably wide tyre (35mm+) that is built as lightly as a narrow "fast" tyre, and that's what is needed for a proper comparison test.

Why do you all want to go faster so badly?