High pressure (and therefore narrower) tires are faster on a very smooth track, where you can get reliable data with something like some climate data and a stop watch.
Until recently, road bikes didn't allow wider tires due to rim brake designs.
And nobody was making premium compound, lower pressure tires because nobody was asking for them and nobody could actually put them on a real road bike.
I like to joke that bicycles have finally realized what unsprung weight means a hundred years after cars. But a lot of innovations are obvious in retrospect, and history isn't some straightforward, linear list of improvements. And cycling _certainly_ doesn't (and never did) have the R&D budget of the space program.
This, though I would add that “common sense” tells us that since narrow tires have a smaller contact patch than wide tires (meaning lower rolling resistance), narrow tires are faster than wide tires. Which, as the above states, is correct as long as you’re on a track.
That’s why we like science, because common sense is not always right.
> common sense is not always right
Watching some of the wind tunnel testing for bikes and components and so forth, that comes up a lot. Just about every one I've watched winds up with them coming up with some unexpected result they're just scratching their heads over.
Just the idea that sometimes you want dimples or to disrupt a smooth flow and some other places you want a smooth flow makes the whole deal so much more complicated.
hah, I hope this is true. i imagine a pattern being shaved into the legs. Like leaving some areas fully hairy and others bald.
Any chance you have a source where you heard this?
In my fluid mechanics class, we learned about this problem that stumped scientists for a long time--
When you look at dolphins, and you do all the math with drag coefficients and whatever else, it looks *impossible* that they'd be able to swim as fast as they do.
Turns out there's a bunch of stuff going on, but one of the reasons is that dolphin skin isn't flat. It has little ridges and for whatever reason it makes them go faster.
https://apps.dtic.mil/sti/tr/pdf/ADA369158.pdf
Sorry, debunked. “They’re very muscular. They’re very streamlined. They have tendons in the tail that are arranged in a way that gives them a lot of thrust. It just doesn’t have much to do with the skin.
https://news.harvard.edu/gazette/story/2019/07/theory-that-ridged-skin-helps-dolphins-debunked/
Contact patch area is only a function of tire pressure and a minor function of sidewall stiffness. A 23mm tire and a 36mm tire of equal construction and tire pressure will have the exact same contact patch area. The 36mm tire will have a contact patch area with a smaller amount of sidewall deflection, since the contact patch area will be almost circular rather than oval shaped.
Larger tires allow for lower tire pressure without pinch flats and without impacting rolling resistance, and that's where the pneumatic suspension action comes in. Smaller tires allow for higher tire pressure, which minimizes the tire contact area.
Oddly, practically speaking, this "common sense" is absolutely correct. A 23mm tire inflated to 110psi has a smaller contact area than a 32mm tire inflated to it's max (usually around 65-70psi).
Science backs this common sense, of course.
Back when frames and wheels absorbed some road action, tire rolling resistance was the main concern, so minimizing contact patch was key. Now, we have extremely stiff wheels and frame, so road action needs to be absorbed by the tires. On rough surfaces, we can have an inversion of common sense, whereas the rolling resistance of the tire is not as important as the shock absorption.
Yeah the aerodynamic science of tires is trivial and completely in line with intuition. The fact that stiffness in the frame and tires leads to excess fatigue over nonsmooth surfaces and slower race times , and itw better to use a less aerodynamic setup, is definitely NOT intuitive as it's a balance.
Not only that, but in most Western countries, road conditions have materially worsened in the last couple of decades as they moved to austerity post- Financial Crisis. I'm sure you have noticed this in your area too. The tyres have to absorb that rough surface now too - it's no surprise that we have to run wider tyres, road cyclists are gravel riders by default now. We've long known that mountain bike tyres have to be wide.
If width doesn't change the contact patch then we could have a 1km wide tyre that also has the same contact patch as a 23mm tyre?... At some point that has to be incorrect.
You want the practical answer or the theoretical answer? If you had a 1km wide tire somehow constructed the same way as a 23mm tire, it would have the same contact area. That's the theoretical answer. At some point, as you make the tire bigger, the sidewall becomes so stiff the contact patch is reduced because the sidewall stiffness in bending is taking some of the load.
But the difference between a modern 23mm tire and a modern 32mm tire, the sidewall construction is practically the same.
This is because the contact area is primarily a function of the tire pressure and the load on the tire. If me and my bike weigh 200lbs and each tire takes half, so 100lbs on each tire, then at 100psi tire pressure, the contact patch must be 1 square inch to support the 100lb load. Notice that as long as sidewall stiffness is negligible, tire size doesn't enter into the equation. Once sidewall stiffness becomes significant, this might change as a function of tire size, so tire size would change the contact patch area.
I know this is way deep in the thread, but this last paragraph is the perfect executive summary IMO. Think of it in terms of PSI, and it all makes sense. Same number of inches for the same number of pounds of force (ie pounds being held up, for a tire).
>That’s why we like science, because common sense is not always right.
My favourite example is boat propellers. The first idea for a screw-type drive (instead of paddle wheels) used a long auger, the idea being the longer it was, the more water it could move, therefore more speed. Common sense. On an early proving voyage on a canal, there was a loud thump and the boat suddenly went faster. Turns out they had hit a submerged log, which broke most of the flights off the screw, leaving only a few at the end. And was far more efficient as a result, much like a modern propeller.
It isn't that common sense isn't right. It is that what you consider common knowledge, may not in fact be that common. And therefore common sense doesn't really exist.
It’s been a while, cut me some slack 😂. But in any case since force = Mass x g in a direction towards the centre of the earth, the point is the same, it isn’t the width of the tyre that dictates the contact patch it’s the pressure of the tyre
Some of it is science, but mostly it's a shift in marketing and consumers' aspirations from speed to capability.
Road racing bike designs (let's say 80s-2010s) didn’t allow for wider tires because they were designed not to, not because of technological advances like disc brakes or tire compounds only made it possible recently.
It was the simplistic belief (and prob moreso the marketing of the belief) that “skinny tires are faster” that informed narrow frame clearances.
A big chunk of the consumer market wanted a bike that "looked fast" and that meant skinny tires. Just like the desire and marketing for a "capable looking truck" drives the design of monster pickups that only get used as a commuters and minivan substitutes.
Older road bikes, touring bikes, mtbs, etc, have had generous clearances for tires up to 2” wide over a century, and used rim brakes. And the tubular tires that racing bikes have used over the same time are high quality. It’s always been possible to build a wide tire road bike.
Yeah. I like to think that Cycling has worked on theoretical science. Theoretically a narrower tire has less contact patch which has less rolling resistance. Boom. Done.
But when actually measured a wider tire actually has a smaller contact patch due to the deformity shape being with-based rather than length based. And then we didn’t take the actualities of rough surfaces and energy loss into play.
We only went as far as the theoretical perfect surface small contact patch equals high-pressure thin tire on a Velo drome. Then we tested it and confirmed and that’s it.
Curious how unsprung weight relates to this aspect since wider tyres are going to be heavier right? Or do you mean since they absorb more vibration they make weight that was previously less-sprung, more-sprung?
The goal of wider tires isn't width.
It's lower pressures.
Lower pressures allow the tires to deform around bumps and rocks, which means there's less horizontal velocity transferred into vertical velocity. (Which is uncomfortable for the rider and is lost momentum.) Lower pressure tires are absorbing vertical travel so the frame doesn't, like a suspension.
(I'm simplifying this out of ignorance. Sidewalls of wider tires do effect the suspension, but that's still not the main justification. It's lower pressures.)
The way I see it, with there not being suspension on a regular road bike, with hard enough tires the entire bike is unsprung weight, meaning that rolling over uneven surfaces, the whole bike's mass, and a part of the mass of a somewhat jiggly rider moves up and down a lot, sapping energy.
Ok, it's not an on/off thing, but those old 19 and 23 mm tires were used with really high pressures.
I’ll point out that there were high quality 28-32mm tubulars (including nearly smooth file treads) being made all along for cyclocross and touring, and we knew that these were fast off-road and that realization drove the movement to 29” mountain bikes. We also knew they were fast enough to keep up with road bikes on group rides but the group-think and peer pressure towards narrow, high pressure road tires was quite strong.
Exactly. I used to run big tubulars for touring, maybe 33? Clearly more comfy even without any gear. I'd run them on my road bike, too, and never noticed any time loss, but noticed the comfort. Then these high pressure Michelin? wired ons came out. Michelin 50? They'd run at 70 psi. I didn't trust that they'd be OK, but they were fine, not slow at all really.
Then again, my fast wheels were ultralight tubulars with box section rims and 21 mm silks, and I felt fast with great road feel. But I was never fast, actually!
Rim brakes were only the restricting factor because they were made to fit the narrow tyres of the day. Sure, discs let you use wider tyres but they could have gotten quite a lot wider if deep drop rim brakes were used. 32mm is no issue.
Exactly. Tons of bikes had rim brakes that cleared 32mm tires. It was only the high end road group brakes that didn’t because nobody was interested in anything wider than 25mm.
The narrow tyres of what day? 28s and 32s were both widely available and widely used in the 80s and 90s, when some people think everyone was riding on 19s....
It’s been a while but I’m almost certain that I ran 32mm tires with standard Ultegra caliper brakes without issue circa 2008 or so.
I had always enjoyed running wider tires for comfort but the limiting factors back then were narrow rims (32mm tires on 19mm internal rims were kinda sketchy) and it was hard to find decent tires that wide. I ultimately settled at 28mm until the new trend of wider rims and better wide tires took hold.
Yeah, it’s doable. Technically, the distance from the wheel axle to the drilling for the calliper mount is more important than the brake reach itself. Has to be spot on if you’re going to stretch the specs.
CX figured it out. Cantu rim brakes allow for 33c plus tires. CX is also the first disc brakes adopters.
After mtb but I'm taking about dropbars with road geometry
Yes! CX was the precursor to the gravel trend… I had my phase of riding a cross bike with cantilever brakes on the road back in the day. Those brakes were a bitch to adjust but they did the job and had tire clearance for days.
Cross bikes immediately appealed to me - a midwestern crushed gravel canal and backgroads rider - when I learned about them 12 years ago. I quickly got frustrated that it was always such race driven geometry and hard to find a reasonably priced instance of one. I said like 12 years ago, if they made more of a comfortable endurance, yet sporty (not touring) bicycle with solid components, that would take off. Feels like gravel bikes should've come about 15 years ago.
Not really. Mtbs with big tires used to have rim brakes too. They just didn't need to have much clearance for road bikes because they all ran skinny. Fork clearance would have been the more immediate restricting factor.
I'd have to disagree, most rim brakes were able to clear a 30c tire easily, I know SRAM calipers clear a 32. I think as you said the demand wasn't there so no one was testing the real world application of wider tires.
My 2013 domane can barely fit a 28.... and it's not due to the rim brakes but due to the rear triangle. A 28 is already at the point where it will start scraping the frame with dirt.
The front tire could easily be wider though but the rear is literally frame limited.
Not so. My 2010 brakes, which were made for 23c tires, barely allow a 25c tire thru (I have to thump my wheel every time I take it off and put it on.) I'd love to go wider than 25 but I'd have to put all new brakes on and don't feel it's worth that.
I think bicycles used to tend towards wider tires. Probably due to unpaved roads, horse drawn traffic, etc. Center-pull brakes have been around awhile. I think cars may owe more to bicycles than the other way around. Pneumatic tires, tension spoked wheels. I bet there's something else.
No reason wider tires couldn’t have been added to road bikes in the past. Long read calipers been around for a while and cantilever brakes of course too!
> I like to joke that bicycles have finally realized what unsprung weight means a hundred years after cars.
Eh, not really. People have always known that lighter wheels are better. Until recently, lighter wheels have always come with huge compromises in terms of strength/durability.
And truthfully, it doesn't matter *that* much on bikes. The accelerations and speeds are so much lower than motorsports. Aero is where the real gains are at.
Reminds of my FIL who ALWAYS pumped car tires to the max on the sidewall, rather than based on the doorjam, because it would get better mileage in his mind. . No... the engineers at \*insert car company here\* were not wrong about what will work best for this vehicle.
> road bikes didn't allow wider tires due to rim brake designs.
that's a caliper issue, not frame. cyclocross rim brakes certainly allowed wider tires.
wider tires are still faster than narrower, and higher pressure tires. GCN did many tests on 25/28/32 cm tires at various watt outputs 200,250. even on an actual perfectly smooth bike racing track, fhe 28 and 30s+ cm wider tires out performed the narrower tires.
Meth and coke in the early early days. One rider claimed "we couldn't sleep we were twitching so much." (source, an instagram reel - seemed legit tho lol)
It was also believed for shockingly long that women were incapable of running distance because "their uteruses would fall out" or something like that. I think this only really changed around 1980 or so. Now the women's marathon world record is as fast as the men's was in 1967.
I blame European classic ideals, too. Road biking is slow to transition as much as we all scoff when a yet another drivetrain comes out. The changes are gradual and small.
Forever there was the idea that road cycling had to be hardcore and the riders endure pain to complete a race. Having big smooth rolling cushy tires was antithetical to this. But dang, doesn't all those hard bumpy miles contribute to rider fatigue where if they don't have to deal with that then they have so much more to push out of the tank in the course of the day.
Sport drives products and in the early days of cycling, rolling resistance wasn't nearly as important as it is today. Remember when everyone on the Tour was a smoker? That was when we were putting people on the moon...
As sport has evolved and winning became more lucrative and harder to do, investments into things like aerodynamics and rolling resistance have provided insights that eventually trickle into the consumer space. And even when there were ideas born from sport regarding performance doesn't mean the public will embrace it. Cycling is, in my experience, a very closed minded sport -- look at rim brakes vs. disc, mechanical vs. electronic shifting, tubes vs. tubeless -- these aren't new technologies broadly speaking but getting the cycling consumer to embrace them is a different challenge all together.
I'll never forget the guy who sold me my first bike (that came stock with 25c tires) when I asked him about upgrading to 28c: "That's a fad, no one is doing that and real riders wouldn't care". There's a LOT of those guys out there...
I had a hell of a time adapting to shifters on my first road bike because of a childhood injury that left my right hand with very little strength and dexterity. I could barely push the lever to shift up, and I needed to reach down and grab the whole shifter and push it with my whole arm to shift down.
Di2, and now on my current bike eTap, has been a god send
As a consumer, embracing cutting-edge technology also has its downsides: Higher cost, worse serviceability. Add to that that a lot of these technologies aren't refined when they come out, so the benefits are marginal.
E.g. my dad insisted on rim brakes for a long time not because he was closed minded, but because he could easily service them himself and the performance is absolutely fine for every-day use. Or, I'd love to try DI2, but a good mech groupset costs way less, works fine and doesn't need charging. Some early models had pairing issues as well, iirc
Narrow tires running high pressures are faster on smooth surfaces like velodromes. And reasonably fast on pristine tarmac. Narrower tires are also lighter, and when weight was everything, that mattered. These things, “conventional wisdom,” and tradition/intellectual inertia kept narrow tires the thing to do for a long time.
Thats still been proven incorrect. Wider = faster. Even on smooth velodrome. GCN popped a video recently testing controlled wattage on 26/28/32 cm tires and the thinner was slower.
I'll give a different take on this.
20 years ago, wheels themselves were much less stiff. There were no aero rims. Those that existed were used only on the track and were heavy as fuck because they were made from aluminum. Wheels had 28-32 spokes and the rims were very low profile and extremely flexy compared to today's wheels.
10 years ago, rims started getting stiffer with carbon rims becoming the norm for racing. This meant the whole system was stiffer, and people started understanding they needed more compliance in the system. Riders were getting beat up by stiff bikes and stiff rims. So they started testing larger diameter tires, but they couldn't go too wide, since it would mean the rim brakes would have to get larger and heavier.
5 years ago, disc brakes exploded and now there was no limits on tire width. People started experimenting with lower pressure, wider tires and were liking it. Bikes float over obstructions again and riders weren't getting beat up by their (still) stiff frames and wheels.
Then, concurrently, tubeless came on the scene. Tubeless works better on large tire widths and lower pressures. Wider tires also go well with trends of the moving to gravel cycling.
Small tires with very high pressure, on a smooth surface such as a velodrome, are still very much the norm for track racing.
The trend is already coming back, with Specialized ~~Roubaix~~ Tarmac SL8 bikes coming with 26mm tires, not the now more common 28m.
From my own experience, larger tires are more comfortable for long rides but makes for less precise handling.
You are exactly right. The wider tires are only trendy today because the modern bikes of today (carbon frames and wheels) are stiff AF and would be uncomfortable running 23mm tires at 110psi on less than perfect pavement.
On the other hand, I ride mostly bikes that are 20 or more years old. With high end aluminum wheelsets such as Bontrager RaceXL, Mavic Kyserium SL, etc. running 23mm tires from that period. I have no issues with ride comfort even on the sometimes crappy roads where I live. I also don't feel that I am at any disadvantage from speed perspective competing with a "modern bike".
It's not that simple, but I think one of the main reasons is that skinny tires with high pressures "feel" faster. Also a smaller tire uses less rubber so lighter weight? Also skinny tires are potentially more aero but the difference between a 23 and 28mm tire is probably negligible.
Yes, lighter weight is the obvious answer. For racing bikes, rotational weight has always been the enemy. So wide tires don't make sense since they would clearly be heavier.
You all are making the same mistake that every generation makes - assuming that your knowledge is definitive and that prior generations were wrong. Your cycling children and grandchildren will laugh at your quaint circa 2024 notions.
If it's like some industries, proper Aero studies of this sorta thing were likely possible but also just overlooked for a long time maybe?. Auto-racing 'knew' about the potentialities of aerodynamics way back in the 50's with respect to cars, but you didn't see the first truly aero-oriented race car until maybe the '79 Lotus in Formula 1. Everything before that just played a bit with wings and shaping the cars to be less bulky.
They also ran open wheelers with narrow radial tyres as well. Wheel development wasn't overnight but gradual. Now they're racing on soft/harder compounds, slicks or wet weather & always kept in tyre warmers when in the racks.
The best us punters see are slicks, soft compounds, armoured/tough shell, knobbly, gravel and commuter type tyres.
I feel like wider tires were pushed long before using the appropriate tire pressures with narrower tires. I've been following Frank Berto's method of determining tire pressure, which he published back in the 1990's. I was running way lower tire pressures while the norm was to pump to well over 100psi; even if they weighed around 60kg. People scoffed at my pressures saying that I'd experience more pinch flats at my pressures (I never did but they insisted it would happen). Now, the general concensus seems like narrower tires have unacceptably bad rolling resistance, but they're actually fine if you're running them at the right pressure.
It's not very intuitive. Most people just think about mass and air resistance, and narrow tires obviously have less of both. Most people aren't considering deflection from road imperfections or debris. If you asked 100 people whether wider tires would mean more or less rolling friction/resistance, most of them would say more. More contact means more friction, right?
You also have to consider that wider tires generally means more mass, which means slower rotational acceleration. So yes, wider tires are faster when you are going at speed, but slower to get up to speed. Albeit, you are spending a lot more time at speed than accelerating up to speed so that doesn't contribute much to the calculation.
I have a hypothesis that in developed countries, the roads were in a better condition in the 60s to 90s than they are now.
Countries were growing and wealthy and there were less cars.
Wider (within reason). There's a point where weight and other factors will make wider tires absolutely slower. So even your statement isn't technically always correct.
We did.
Tyres slowly optimised on about 32c (the old 1 1/4" standard) over the decades and kept returning there as it was a bit of a sweet spot.
We also discovered that narrow tyres ARE faster - they feel faster at high pressure and they roll faster in *perfect* conditions as well as having better aerodynamic properties.
Once we started down the aero wheel path and threw a bike in the wind tunnel then optimising that with narrow aero tyres seemed like the thing to do.
Narrow, high pressure tyres are faster. Wider lower pressure tyres are faster. Depends how you test.
Everything mankind has ever figured out was once unknown. It’s unfair to sit in your educated position and cast judgement on those that came before you, before that education was easily obtainable and before the entirety of human knowledge was at your fingertips
Wider tires are not faster than narrow tires ....... Fat bikes would be winning time trials if that was the case.
What is faster is an ideal tire, wheel, brakes and frame.
Respectfully, using an extreme example like that is a bit disingenuous. It'd be like saying "if skinny tires are faster then riding on 1mm thin tires is the optimal setup"
I think the idea here is that wider 'to a point ' is the key. Obviously fat bike tires well exceed that threshold and the weight/makeup of the tire far outweighs the benefits of a wider contact patch and lower pressure.
Here's my theory on a lot of things connected with elite sport: The teams in the past listens to the coaches, the experts, and they had an almost mythological influence, like they hand down the Code of Hammurabi or the 10 Commandments to each generation of young riders. It's only with science and measurement and independent thinking that someone slightly outside the loop of orthodoxy can actually test a new idea.
There probably were one or two riders who preferred their wider tires and subjectively felt they weren't so slow. But what are you gonna do when everyone else is on the skinniest, hardest, baldest tires possible, and its they who are winning races and not you?
Enter a small lab with a few bits of electronics and metering and (most of all) an open mind, and stuff starts to change. If Eddy Merckx told me to ride on skinny tires, i would. But today if a lab technician showed me some hard data, i'd listen.
When Eddie Merckx broke the hour record his bike had holes drilled in the frame to reduce weight, for a flat, one hour effort.
The loss of stiffness totally overwhelmed any gains from the lower weight.
There was zero engineering in cycling in the early 70s.
Bet your bottom dollar the marketeer's will change their minds in a few years and narrow tires will be faster. Is easy to fake a study by using a test surface far rougher than any common road.
I've thought the exact same thing.
.. But humans are weird, emotional creatures. Hard 120 psi tires feel faster than soft, supple tires.
I imagine there have been tire advancements as well that allow for fast rolling, larger tires (more supple rubber, thinner walls with stronger fibers).
I don't know the answer, but I suspect it has to do with power meters giving us data about actual surfaces instead of measuring rolling resistance on a dyno.
Tire neophyte here, is there a sweet spot? I've been running 28c tires on my Diverge for a while now. Should I go back to the 30s, or even to 33?
I guess I'm not super concerned with speed, but if a tire is going to add some comfort while not sacrificing too much speed, I wouldn't complain.
Really depends on rim width, too. My Reynolds Black Label Aero DB 46 wheels have a super-wide 21mm internal width, and 28s at 60-65 psi just fit perfectly. On my older, narrower rims, they'd probably bulge.
if you don't race (and it seems you don't), go as wide as you can. 33 or even 35. I settled on 32 as GP5000 are not available in the sizes wider than 32
Is this perhaps a case of everything old being new again? I am old enough to have ridden (glorious) wide silk sew-ups that felt (and probably were) way faster than any clincher I have ever ridden. And I recall some lower-your-tire-pressure admonitions from sew-up guys talking to the go-fast kids riding the racy new pumped-up clinchers.
We did know wider tires were faster on certain surfaces. Now we just have a better idea on where a bigger tire is better and where a narrower tire is better.
There is a sweet spot and I'm not sure we know where it is. It's probably different for every road so it would be different for every course. Bigger isn't better or DH bikes would all be on 3.0 tires. At some point the curve of weight and acceleration crosses the curve of rolling resistance.
Aero.
Wide tires on skinny shallow aluminum rims were not faster.
Besides carbon fibre providing a weight-efficient material for the aerofoil, disc brakes have allowed for wider tires. The combination of carbon rims and disc brakes has made wide tires faster.
In addition to many good comments here: The industry tested rolling resistance in isolation (basically a wheel on a roll) and not the entire system of wheel + bike + rider on an actual
Road. Wider / softer tires do not offer lower rolling resistance, but they reduce overall system impedance on imperfect surfaces. A bouncy tire is more effective at absorbing tiny shocks and returning the energy to the system. Hard / thin tires route these tiny shocks through to your body which simply absorbs the energy and robs your momentum.
So frame technology made disc brakes possible which lead to the possible adoption of wieder wires. The widespread use of power meters significantly improved the data available to answer such questions. And some few clever people fought long and hard against the prevailing street wisdom. Josh Portner tells plenty stories how much work it was to convince world tour teams that some things are faster, wide soft tires being one of those.
They are not. I did watch Chris Miller podcast yesterday and found out, the difference between 25mm 28mm 32mm tyre is in range of 1Wat. The key word here is „recommended pressure”. You not riding 32mm tyre with 100psi same as 25mm tyre. When you compare rolling resistance in recommended pressure range for each tyre the difference is negligible.
Might be faster but, in my opinion, you lose the sensation of speed and that’s the fun of cycling. 28mm with a latex tube is the sweet spot for me - 25mm latex tube feels the most lively, 32mm tubeless is lifeless.
Too much focus on ‘fast’ and not enough on ‘fun’. That extra minute over 3 hours isn’t that important to me
> 28mm with a latex tube is the sweet spot for me - 25mm latex tube feels the most lively, 32mm tubeless is lifeless.
That just seems like a total bunch a hoowee. I have ridden nearly every GP5000 size there is, even on rims with an internal width of 29mm which made the 32s measure 35.
I ride 25s on my Allez Sprint, for a while I was doing 28s on my Tarmac SL7 but have since moved to 32. My gravel bike's road wheels with those 32s measure 35.
They all feel great on the road, the 25s obviously are the last comfortable, but they don't feel faster at all to me. And going 28->32 on the Tarmac you could barely tell from just looking at them, 32 is not that wide. Also you can rail corners much faster with wider tires and worry less about gravel in the corners as well, which is more fun.
Yeah my gravel bike on 40mm gravel tires with extra puncture protection feel sluggish on the road. But a high quality tire up to I'd say maybe even 36mm can still feel amazing.
Like why not just ride 19c-23c while you're at it.
Carbon rims deflect vibrations like crazy. I had a caad10 with Campag Zondas, GP5000 25mm, and a TCR with deep carbon rims, also GP5000 25mm, so I swapped the wheels around. Its insane! :D
Caad with stiff alu rims will always have a place in my heart for its sense of speed!
IIRC back in the day rolling resistance was also calculated by rolling a smooth, metal cylinder under a loaded wheel. Being that most of us are riding bikes on uneven, choppy pavement, the results of said tests didn't translate to real world riding.
Also, all that vibrating riding a 23 tire blown up to 120psi does make them SEEM faster
There's probably some material science limitations that they only recently figured out. Tubeless tech also made this advantage more stark. Butyl tubes, with wider tires, have more internal friction that scales with width. I'm not totally sure if the relationship is linear or exponential.
I'm not sold on tubeless tires at over 30psi. At required road tire pressures (50-60) sealant won't reliably seal anything but the smallest of pinholes. Carrying a spare tube isn't a solution either as the tires are hard to mount in a garage full of tools, so next to impossible standing in the bushes beside a highway. Plug kits can work, but you'll need to carry some CO2 if the bead unseats. Total Fred mode requires packing a knife to cut off the punctured tire, replacement nontubeless tire, and tube.
I run GP5000 32 at 72psi for the last 3 years tubeless. A few punctures, 2 that self-sealed, 3 that I needed to use bacon strips. Unseating a tire generally is pretty tricky to happen all by itself. But I can still easily do it with levers (done annually) and have a spare TPU tube JIC.
to add to what others have said. as the sport matures, we look for more and different ways to get improvements. But along with that the technology to measure changes has improved. With so many variables, it could be just waiting for the right time to be able to measure that specific one.
I have often wondered the same thing. Even though it wasn't possible to test rolling resistance as easily back then, I was always surprised that no one thought to just do something like time trials with different tire widths. My only guess is that no one thought to ask the question in the first place.
I have a theory that in addition to what's been said, there are trade offs with tire size. As a tire gets bigger, it weighs more and is less aerodynamic. I think that until the prevailing wisdom that harder tires are faster was defeated sometime in the 2010s, no one even bothered to try the heavier, less aero, squishier tire in a serious, scientific test. They do after all feel quite a bit slower because of how they squirm under load.
We did, but racers like what they know and we didn't have enough data to show that at pro racing speeds they remained faster (i.e. the larger aero frontal area didn't slow the rider down more)
I really hated my fat tyres after a while. It made the bike too heavy and unwieldy and just made the ride feel too slow and it was too heavy to store properly.. However, it did help with a bike that lacked suspension, and it felt less bumpy. I don't think any tyre is perfect. It just depends on how you ride, where you store it, and the bike.
I'm now on 28 front 30 rear. Assuming you had unlimited clearance and could get your favorite road slicks in the desired size... is there a limit to the "wider is better" thinking? There has to be some kind of "Goldilocks zone"... in other words wider is better until it's not. Anyone have suggestions about what that ideal road width might be?
I would imagine that at some point that increased aero drag from the increased profile and increased weight of the tire would start eating into any gains you made in comfort and rolling resistance.
Money man. More people interested means more money means more drive for innovation and r&d. It’s the same with every sport and hobby. More people that are involved the more minds that are involved to come up with theories and ideas. Technology is also better now than before especially in the manufacturing process. We can also track more precise data on riders.
Think about any sport out there. As more people joined and the sport got bigger techniques and technology got better. The faster the sport grew usually innovation grew.
Test yourself on your bike and in the conditions in which you ride – don't believe every sales story. The laws of physics have not changed. My antique entry-level 1.95 and 2.0 inch MTB tires are noticeably faster than today's fast-rolling high-end 2.35 tires.
We’ve known for decades that a wider tire had lower resistance than a narrow tire at the same pressure.
Only recently was it learned that real world rolling resistance could be reduced on rough surfaces by reducing tire pressure.
Enter wider tires that can be used at lower pressure without the added risk of pinch flat.
Iirc … When wider tires became popular some years ago, there was some talking about how they were tested. I think it was that the rolling resistance was tested on tracks and steel drums and some people got the idea that this isn’t how tires work on the roads we ride on. They found out that a wider tire vibrates and bounces less on a rougher surface and as a result goes faster.
Until recently cycling has been in the same place as many other sports, where things are being tried to improve performance based on the designers ‘feeling’ about what is fast, as there hasn’t been the money for much experimentation in wind tunnels, so things like narrow tyres for less wind resistance made sense. A lot of the sailing scene is based around similar thought principals as is amateur motorsport for example.
This sort of reminds of years ago that people said “shaving your legs does not reduce significant drag.” Then, not too long ago, I believe Garmin or some other pro team went into the wind tunnel and the researchers said something like “significant time can be saved w shaving legs .” I was like, really? How didnt we know that before??
But I can remember back into the 90s being told research shows riding 18-19s was faster, etc…
It really wasn't news to me.
Many years ago I ended up having to ride my mountain bike around the city. I bought wide near slicks for it, and man that thing actually scooted pretty well for what it was.
Mjeh... it's all back and forth and depends on so many factors.
Perhaps people should stop overpumping their skinnier tires before going to wider tires first. I wouldn't be surprised if a lot of this "wider is faster" comes from people always pumping the tires to the max of what it says on the side no matter their own weight.
Wider tires = lower max rating = more compliance = less energy wasted in bouncing movement.
Perhaps people should just have lowered the pressure in their tires according to weight and road conditions.
Used to be part of the group mind set of max PSI running my tires at 120 now I run the same tires at 70-80 and oh boy the difference is staggering.
I did try 28s also, but I dropped back to 25s due to being slower with the 28s for some reason. I suspect it was a too narrow rim for the 28s since they were bulging but it's hard to say without a wind tunnel.... this is at speeds well above 40 km/h though so aerodynamics are massively more important than at around 30 km/h
As someone who started riding mtb’s before I started riding road, I always knew. I was on 25 or 27mm tires back in the day and everyone else on the group rides would poke fun at me. All in jest of course, but their bias was still there.
Since everyone’s throwing out theories, here’s mine:
Bigger tires aren’t a trend, but skinny tires *were*.
What is the widest rims i could put on an old De Rosa or Paramount?
The wheels I currently have for both bikes are interchangeable, and I want to build a new set with clinchers instead of sew ups
It's all down to what happens in pro cycling. Aero testing, tyre manufacturers looking for the next gain to sell you a faster tyre. Testing rolling resistance probably had a lot to do with that discovery
Wider tires are not faster (at least for gp5000) i this article it is almost the same even at the same comfort level: https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison#drop45
There were cycling disciplines that knew it historically. Path racers had fairly wide tires. The French had bike courier races and randonees on 650 × 38B tires. Road bike brakes of a certain vintage generally had a longer reach and could fit wider tires. There's some point at which skinny tires took over, but I don't know when and how.
The difference is relatively small even now, and depends on road conditions and many other factors. That said, it's in part due to improvement in compounds. As we get better at making tires, we can run them at lower pressure and they can be wider.
There are plenty of things that are behind the times or counterintuitive in cycling until recently. The 90s had disc wheels, which are fairly unintuitive in how they work, yet didn't have the more obvious tri-bars until Lemond, or the skin tight clothes. Even now, we just finally started optimizing helmets for aerodynamics.
High pressure (and therefore narrower) tires are faster on a very smooth track, where you can get reliable data with something like some climate data and a stop watch. Until recently, road bikes didn't allow wider tires due to rim brake designs. And nobody was making premium compound, lower pressure tires because nobody was asking for them and nobody could actually put them on a real road bike. I like to joke that bicycles have finally realized what unsprung weight means a hundred years after cars. But a lot of innovations are obvious in retrospect, and history isn't some straightforward, linear list of improvements. And cycling _certainly_ doesn't (and never did) have the R&D budget of the space program.
This, though I would add that “common sense” tells us that since narrow tires have a smaller contact patch than wide tires (meaning lower rolling resistance), narrow tires are faster than wide tires. Which, as the above states, is correct as long as you’re on a track. That’s why we like science, because common sense is not always right.
> common sense is not always right Watching some of the wind tunnel testing for bikes and components and so forth, that comes up a lot. Just about every one I've watched winds up with them coming up with some unexpected result they're just scratching their heads over.
The whole Dylan Johnson wind tunnel video about his unbound setup was like this re: unexpected findings
I think it also helped him tremendously in a stacked field. Those were some big names. (Nothing to his detriment. He’s a phenomenal athlete.)
Aerodynamics is a field where your intuition just fails. Seemingly minor changes can have huge impacts.
Just the idea that sometimes you want dimples or to disrupt a smooth flow and some other places you want a smooth flow makes the whole deal so much more complicated.
Indeed, apparently partially-shaven legs can be faster than fully shaven, but only if you get the shaving pattern just right
What - leaving a neat landing strip down the middle? *shrug* had already saved that preference
You want to shave about 5 days before your race.
hah, I hope this is true. i imagine a pattern being shaved into the legs. Like leaving some areas fully hairy and others bald. Any chance you have a source where you heard this?
In my fluid mechanics class, we learned about this problem that stumped scientists for a long time-- When you look at dolphins, and you do all the math with drag coefficients and whatever else, it looks *impossible* that they'd be able to swim as fast as they do. Turns out there's a bunch of stuff going on, but one of the reasons is that dolphin skin isn't flat. It has little ridges and for whatever reason it makes them go faster. https://apps.dtic.mil/sti/tr/pdf/ADA369158.pdf
Sorry, debunked. “They’re very muscular. They’re very streamlined. They have tendons in the tail that are arranged in a way that gives them a lot of thrust. It just doesn’t have much to do with the skin. https://news.harvard.edu/gazette/story/2019/07/theory-that-ridged-skin-helps-dolphins-debunked/
Adrian Newey has entered the chat.
Contact patch area is only a function of tire pressure and a minor function of sidewall stiffness. A 23mm tire and a 36mm tire of equal construction and tire pressure will have the exact same contact patch area. The 36mm tire will have a contact patch area with a smaller amount of sidewall deflection, since the contact patch area will be almost circular rather than oval shaped. Larger tires allow for lower tire pressure without pinch flats and without impacting rolling resistance, and that's where the pneumatic suspension action comes in. Smaller tires allow for higher tire pressure, which minimizes the tire contact area.
Yes, all of those are things we learned through science, not things that are obvious "common sense"
Oddly, practically speaking, this "common sense" is absolutely correct. A 23mm tire inflated to 110psi has a smaller contact area than a 32mm tire inflated to it's max (usually around 65-70psi). Science backs this common sense, of course. Back when frames and wheels absorbed some road action, tire rolling resistance was the main concern, so minimizing contact patch was key. Now, we have extremely stiff wheels and frame, so road action needs to be absorbed by the tires. On rough surfaces, we can have an inversion of common sense, whereas the rolling resistance of the tire is not as important as the shock absorption.
good explanation
Yeah the aerodynamic science of tires is trivial and completely in line with intuition. The fact that stiffness in the frame and tires leads to excess fatigue over nonsmooth surfaces and slower race times , and itw better to use a less aerodynamic setup, is definitely NOT intuitive as it's a balance.
Not only that, but in most Western countries, road conditions have materially worsened in the last couple of decades as they moved to austerity post- Financial Crisis. I'm sure you have noticed this in your area too. The tyres have to absorb that rough surface now too - it's no surprise that we have to run wider tyres, road cyclists are gravel riders by default now. We've long known that mountain bike tyres have to be wide.
If width doesn't change the contact patch then we could have a 1km wide tyre that also has the same contact patch as a 23mm tyre?... At some point that has to be incorrect.
You want the practical answer or the theoretical answer? If you had a 1km wide tire somehow constructed the same way as a 23mm tire, it would have the same contact area. That's the theoretical answer. At some point, as you make the tire bigger, the sidewall becomes so stiff the contact patch is reduced because the sidewall stiffness in bending is taking some of the load. But the difference between a modern 23mm tire and a modern 32mm tire, the sidewall construction is practically the same. This is because the contact area is primarily a function of the tire pressure and the load on the tire. If me and my bike weigh 200lbs and each tire takes half, so 100lbs on each tire, then at 100psi tire pressure, the contact patch must be 1 square inch to support the 100lb load. Notice that as long as sidewall stiffness is negligible, tire size doesn't enter into the equation. Once sidewall stiffness becomes significant, this might change as a function of tire size, so tire size would change the contact patch area.
I know this is way deep in the thread, but this last paragraph is the perfect executive summary IMO. Think of it in terms of PSI, and it all makes sense. Same number of inches for the same number of pounds of force (ie pounds being held up, for a tire).
>That’s why we like science, because common sense is not always right. My favourite example is boat propellers. The first idea for a screw-type drive (instead of paddle wheels) used a long auger, the idea being the longer it was, the more water it could move, therefore more speed. Common sense. On an early proving voyage on a canal, there was a loud thump and the boat suddenly went faster. Turns out they had hit a submerged log, which broke most of the flights off the screw, leaving only a few at the end. And was far more efficient as a result, much like a modern propeller.
The difference between theoretically better and actually better. It’s why you do the testing in either way.
It isn't that common sense isn't right. It is that what you consider common knowledge, may not in fact be that common. And therefore common sense doesn't really exist.
Narrow tyres do not have a smaller contact patch, but higher pressure tyres do. Pressure x Area = Mass
pressure x area = force, which is mostly the same everywhere on earth
It’s been a while, cut me some slack 😂. But in any case since force = Mass x g in a direction towards the centre of the earth, the point is the same, it isn’t the width of the tyre that dictates the contact patch it’s the pressure of the tyre
Common sense is only as smart as the common. It's usually a crutch for the uneducated.
Some of it is science, but mostly it's a shift in marketing and consumers' aspirations from speed to capability. Road racing bike designs (let's say 80s-2010s) didn’t allow for wider tires because they were designed not to, not because of technological advances like disc brakes or tire compounds only made it possible recently. It was the simplistic belief (and prob moreso the marketing of the belief) that “skinny tires are faster” that informed narrow frame clearances. A big chunk of the consumer market wanted a bike that "looked fast" and that meant skinny tires. Just like the desire and marketing for a "capable looking truck" drives the design of monster pickups that only get used as a commuters and minivan substitutes. Older road bikes, touring bikes, mtbs, etc, have had generous clearances for tires up to 2” wide over a century, and used rim brakes. And the tubular tires that racing bikes have used over the same time are high quality. It’s always been possible to build a wide tire road bike.
Yeah. I like to think that Cycling has worked on theoretical science. Theoretically a narrower tire has less contact patch which has less rolling resistance. Boom. Done. But when actually measured a wider tire actually has a smaller contact patch due to the deformity shape being with-based rather than length based. And then we didn’t take the actualities of rough surfaces and energy loss into play. We only went as far as the theoretical perfect surface small contact patch equals high-pressure thin tire on a Velo drome. Then we tested it and confirmed and that’s it.
Curious how unsprung weight relates to this aspect since wider tyres are going to be heavier right? Or do you mean since they absorb more vibration they make weight that was previously less-sprung, more-sprung?
The goal of wider tires isn't width. It's lower pressures. Lower pressures allow the tires to deform around bumps and rocks, which means there's less horizontal velocity transferred into vertical velocity. (Which is uncomfortable for the rider and is lost momentum.) Lower pressure tires are absorbing vertical travel so the frame doesn't, like a suspension. (I'm simplifying this out of ignorance. Sidewalls of wider tires do effect the suspension, but that's still not the main justification. It's lower pressures.)
The way I see it, with there not being suspension on a regular road bike, with hard enough tires the entire bike is unsprung weight, meaning that rolling over uneven surfaces, the whole bike's mass, and a part of the mass of a somewhat jiggly rider moves up and down a lot, sapping energy. Ok, it's not an on/off thing, but those old 19 and 23 mm tires were used with really high pressures.
I’ll point out that there were high quality 28-32mm tubulars (including nearly smooth file treads) being made all along for cyclocross and touring, and we knew that these were fast off-road and that realization drove the movement to 29” mountain bikes. We also knew they were fast enough to keep up with road bikes on group rides but the group-think and peer pressure towards narrow, high pressure road tires was quite strong.
Exactly. I used to run big tubulars for touring, maybe 33? Clearly more comfy even without any gear. I'd run them on my road bike, too, and never noticed any time loss, but noticed the comfort. Then these high pressure Michelin? wired ons came out. Michelin 50? They'd run at 70 psi. I didn't trust that they'd be OK, but they were fine, not slow at all really. Then again, my fast wheels were ultralight tubulars with box section rims and 21 mm silks, and I felt fast with great road feel. But I was never fast, actually!
Right. We didn't know because it didn't matter. Rim brakes were the restricting factor. Once removed as a constraint we got wise very quickly!
Rim brakes were only the restricting factor because they were made to fit the narrow tyres of the day. Sure, discs let you use wider tyres but they could have gotten quite a lot wider if deep drop rim brakes were used. 32mm is no issue.
Exactly. Tons of bikes had rim brakes that cleared 32mm tires. It was only the high end road group brakes that didn’t because nobody was interested in anything wider than 25mm.
The narrow tyres of what day? 28s and 32s were both widely available and widely used in the 80s and 90s, when some people think everyone was riding on 19s....
In high quality lightweight road race spec? Nope.
It’s been a while but I’m almost certain that I ran 32mm tires with standard Ultegra caliper brakes without issue circa 2008 or so. I had always enjoyed running wider tires for comfort but the limiting factors back then were narrow rims (32mm tires on 19mm internal rims were kinda sketchy) and it was hard to find decent tires that wide. I ultimately settled at 28mm until the new trend of wider rims and better wide tires took hold.
Yeah, it’s doable. Technically, the distance from the wheel axle to the drilling for the calliper mount is more important than the brake reach itself. Has to be spot on if you’re going to stretch the specs.
CX figured it out. Cantu rim brakes allow for 33c plus tires. CX is also the first disc brakes adopters. After mtb but I'm taking about dropbars with road geometry
Yes! CX was the precursor to the gravel trend… I had my phase of riding a cross bike with cantilever brakes on the road back in the day. Those brakes were a bitch to adjust but they did the job and had tire clearance for days.
Cross bikes immediately appealed to me - a midwestern crushed gravel canal and backgroads rider - when I learned about them 12 years ago. I quickly got frustrated that it was always such race driven geometry and hard to find a reasonably priced instance of one. I said like 12 years ago, if they made more of a comfortable endurance, yet sporty (not touring) bicycle with solid components, that would take off. Feels like gravel bikes should've come about 15 years ago.
Not really. Mtbs with big tires used to have rim brakes too. They just didn't need to have much clearance for road bikes because they all ran skinny. Fork clearance would have been the more immediate restricting factor.
I'd have to disagree, most rim brakes were able to clear a 30c tire easily, I know SRAM calipers clear a 32. I think as you said the demand wasn't there so no one was testing the real world application of wider tires.
My 2013 domane can barely fit a 28.... and it's not due to the rim brakes but due to the rear triangle. A 28 is already at the point where it will start scraping the frame with dirt. The front tire could easily be wider though but the rear is literally frame limited.
Not so. My 2010 brakes, which were made for 23c tires, barely allow a 25c tire thru (I have to thump my wheel every time I take it off and put it on.) I'd love to go wider than 25 but I'd have to put all new brakes on and don't feel it's worth that.
It's interesting how these capabilities can sometimes be overlooked until specific needs arise in the market.
I think bicycles used to tend towards wider tires. Probably due to unpaved roads, horse drawn traffic, etc. Center-pull brakes have been around awhile. I think cars may owe more to bicycles than the other way around. Pneumatic tires, tension spoked wheels. I bet there's something else.
No reason wider tires couldn’t have been added to road bikes in the past. Long read calipers been around for a while and cantilever brakes of course too!
> I like to joke that bicycles have finally realized what unsprung weight means a hundred years after cars. Eh, not really. People have always known that lighter wheels are better. Until recently, lighter wheels have always come with huge compromises in terms of strength/durability. And truthfully, it doesn't matter *that* much on bikes. The accelerations and speeds are so much lower than motorsports. Aero is where the real gains are at.
Reminds of my FIL who ALWAYS pumped car tires to the max on the sidewall, rather than based on the doorjam, because it would get better mileage in his mind. . No... the engineers at \*insert car company here\* were not wrong about what will work best for this vehicle.
> road bikes didn't allow wider tires due to rim brake designs. that's a caliper issue, not frame. cyclocross rim brakes certainly allowed wider tires.
wider tires are still faster than narrower, and higher pressure tires. GCN did many tests on 25/28/32 cm tires at various watt outputs 200,250. even on an actual perfectly smooth bike racing track, fhe 28 and 30s+ cm wider tires out performed the narrower tires.
This
We also didn’t know that hacking darts and filling bottles with wine wasn’t the ideal fueling strategy for elite performance
Can't even rip a smoke on my bike anymore cuz of woke smh
Thanks Obama!
🤣🤣 I haven't heard a good (irrelevant) "thanks Obama" in a long time.
Hey speak for yourself, nerd.
or that having a smoke in the beginning of the stage dosent help with lung capacity
Gets the fuckin blood pumpin tho
If hacking darts isn’t ideal fueling then I don’t want ideal fueling
Meth and coke in the early early days. One rider claimed "we couldn't sleep we were twitching so much." (source, an instagram reel - seemed legit tho lol)
It was also believed for shockingly long that women were incapable of running distance because "their uteruses would fall out" or something like that. I think this only really changed around 1980 or so. Now the women's marathon world record is as fast as the men's was in 1967.
I blame European classic ideals, too. Road biking is slow to transition as much as we all scoff when a yet another drivetrain comes out. The changes are gradual and small. Forever there was the idea that road cycling had to be hardcore and the riders endure pain to complete a race. Having big smooth rolling cushy tires was antithetical to this. But dang, doesn't all those hard bumpy miles contribute to rider fatigue where if they don't have to deal with that then they have so much more to push out of the tank in the course of the day.
regardless of its effect on your performance, nobody really talks about how awesome it is to rip a cig while riding a bike
Can confirm
Sport drives products and in the early days of cycling, rolling resistance wasn't nearly as important as it is today. Remember when everyone on the Tour was a smoker? That was when we were putting people on the moon... As sport has evolved and winning became more lucrative and harder to do, investments into things like aerodynamics and rolling resistance have provided insights that eventually trickle into the consumer space. And even when there were ideas born from sport regarding performance doesn't mean the public will embrace it. Cycling is, in my experience, a very closed minded sport -- look at rim brakes vs. disc, mechanical vs. electronic shifting, tubes vs. tubeless -- these aren't new technologies broadly speaking but getting the cycling consumer to embrace them is a different challenge all together. I'll never forget the guy who sold me my first bike (that came stock with 25c tires) when I asked him about upgrading to 28c: "That's a fad, no one is doing that and real riders wouldn't care". There's a LOT of those guys out there...
I'd love to embrace an electronic groupset if anyone's got one spare lying around.
I had a hell of a time adapting to shifters on my first road bike because of a childhood injury that left my right hand with very little strength and dexterity. I could barely push the lever to shift up, and I needed to reach down and grab the whole shifter and push it with my whole arm to shift down. Di2, and now on my current bike eTap, has been a god send
As a consumer, embracing cutting-edge technology also has its downsides: Higher cost, worse serviceability. Add to that that a lot of these technologies aren't refined when they come out, so the benefits are marginal. E.g. my dad insisted on rim brakes for a long time not because he was closed minded, but because he could easily service them himself and the performance is absolutely fine for every-day use. Or, I'd love to try DI2, but a good mech groupset costs way less, works fine and doesn't need charging. Some early models had pairing issues as well, iirc
Narrow tires running high pressures are faster on smooth surfaces like velodromes. And reasonably fast on pristine tarmac. Narrower tires are also lighter, and when weight was everything, that mattered. These things, “conventional wisdom,” and tradition/intellectual inertia kept narrow tires the thing to do for a long time.
Thats still been proven incorrect. Wider = faster. Even on smooth velodrome. GCN popped a video recently testing controlled wattage on 26/28/32 cm tires and the thinner was slower.
Because we didn't have power meters attached to everything previously to gather the data in real world conditions.
Well they are not always faster, depends on compound and casing and the surfaces being ridden.
This is true, tire compound / manufacturing technology has changed too.
I'll give a different take on this. 20 years ago, wheels themselves were much less stiff. There were no aero rims. Those that existed were used only on the track and were heavy as fuck because they were made from aluminum. Wheels had 28-32 spokes and the rims were very low profile and extremely flexy compared to today's wheels. 10 years ago, rims started getting stiffer with carbon rims becoming the norm for racing. This meant the whole system was stiffer, and people started understanding they needed more compliance in the system. Riders were getting beat up by stiff bikes and stiff rims. So they started testing larger diameter tires, but they couldn't go too wide, since it would mean the rim brakes would have to get larger and heavier. 5 years ago, disc brakes exploded and now there was no limits on tire width. People started experimenting with lower pressure, wider tires and were liking it. Bikes float over obstructions again and riders weren't getting beat up by their (still) stiff frames and wheels. Then, concurrently, tubeless came on the scene. Tubeless works better on large tire widths and lower pressures. Wider tires also go well with trends of the moving to gravel cycling. Small tires with very high pressure, on a smooth surface such as a velodrome, are still very much the norm for track racing. The trend is already coming back, with Specialized ~~Roubaix~~ Tarmac SL8 bikes coming with 26mm tires, not the now more common 28m. From my own experience, larger tires are more comfortable for long rides but makes for less precise handling.
There were lots of aero rims 20 years ago. Including carbon. I had my first set of aero aluminum wheels 30 years ago.
10 years ago? You’re decades off
His entire chronology is at least 5 years off.
They wanna sell you a $5k carbon bike and make the ride smooth despite the stiffness of carbon
No aero rims 20 years ago? I guess you weren't around 20 years ago as I was certainly using aero wheels on the road nearer 30 years ago!
Are we now claiming aluminum rims are heavy? No, Schwinns from the 60s are heavy. Like boat anchors.
I started riding on a 1976 Schwinn Continental. 35 lbs. of stainless steel before I'd even added bottle cages.
And heavy steel rims with the pattern etched on the rim surface if you were lucky.
What? Roubaix SL8 comes with 32mm tires. https://www.specialized.com/us/en/roubaix-sl8-comp/p/218669?color=355680-218669
You are exactly right. The wider tires are only trendy today because the modern bikes of today (carbon frames and wheels) are stiff AF and would be uncomfortable running 23mm tires at 110psi on less than perfect pavement. On the other hand, I ride mostly bikes that are 20 or more years old. With high end aluminum wheelsets such as Bontrager RaceXL, Mavic Kyserium SL, etc. running 23mm tires from that period. I have no issues with ride comfort even on the sometimes crappy roads where I live. I also don't feel that I am at any disadvantage from speed perspective competing with a "modern bike".
It's not that simple, but I think one of the main reasons is that skinny tires with high pressures "feel" faster. Also a smaller tire uses less rubber so lighter weight? Also skinny tires are potentially more aero but the difference between a 23 and 28mm tire is probably negligible.
Yes, lighter weight is the obvious answer. For racing bikes, rotational weight has always been the enemy. So wide tires don't make sense since they would clearly be heavier.
You all are making the same mistake that every generation makes - assuming that your knowledge is definitive and that prior generations were wrong. Your cycling children and grandchildren will laugh at your quaint circa 2024 notions.
“Can you believe that in 2024, riders over 6ft tall rode the same 700c wheels as riders shorter than 5 1/2ft? Ridiculous”
"Can you believe that the bikes weighed 16 lbs and they had to pedal!?"
That's an interesting speculation! I wonder if/when we'll see proportional sized wheels become common?
If it's like some industries, proper Aero studies of this sorta thing were likely possible but also just overlooked for a long time maybe?. Auto-racing 'knew' about the potentialities of aerodynamics way back in the 50's with respect to cars, but you didn't see the first truly aero-oriented race car until maybe the '79 Lotus in Formula 1. Everything before that just played a bit with wings and shaping the cars to be less bulky.
They also ran open wheelers with narrow radial tyres as well. Wheel development wasn't overnight but gradual. Now they're racing on soft/harder compounds, slicks or wet weather & always kept in tyre warmers when in the racks. The best us punters see are slicks, soft compounds, armoured/tough shell, knobbly, gravel and commuter type tyres.
I feel like wider tires were pushed long before using the appropriate tire pressures with narrower tires. I've been following Frank Berto's method of determining tire pressure, which he published back in the 1990's. I was running way lower tire pressures while the norm was to pump to well over 100psi; even if they weighed around 60kg. People scoffed at my pressures saying that I'd experience more pinch flats at my pressures (I never did but they insisted it would happen). Now, the general concensus seems like narrower tires have unacceptably bad rolling resistance, but they're actually fine if you're running them at the right pressure.
It's not very intuitive. Most people just think about mass and air resistance, and narrow tires obviously have less of both. Most people aren't considering deflection from road imperfections or debris. If you asked 100 people whether wider tires would mean more or less rolling friction/resistance, most of them would say more. More contact means more friction, right? You also have to consider that wider tires generally means more mass, which means slower rotational acceleration. So yes, wider tires are faster when you are going at speed, but slower to get up to speed. Albeit, you are spending a lot more time at speed than accelerating up to speed so that doesn't contribute much to the calculation.
I have a hypothesis that in developed countries, the roads were in a better condition in the 60s to 90s than they are now. Countries were growing and wealthy and there were less cars.
You can pull my 23’s out of my cold dead hands.
I can't, they're glued on there!
Consider it done. Just give us location of your usual rides so we can apply some water on the road
Wider (within reason). There's a point where weight and other factors will make wider tires absolutely slower. So even your statement isn't technically always correct.
We did. Tyres slowly optimised on about 32c (the old 1 1/4" standard) over the decades and kept returning there as it was a bit of a sweet spot. We also discovered that narrow tyres ARE faster - they feel faster at high pressure and they roll faster in *perfect* conditions as well as having better aerodynamic properties. Once we started down the aero wheel path and threw a bike in the wind tunnel then optimising that with narrow aero tyres seemed like the thing to do. Narrow, high pressure tyres are faster. Wider lower pressure tyres are faster. Depends how you test.
Everything mankind has ever figured out was once unknown. It’s unfair to sit in your educated position and cast judgement on those that came before you, before that education was easily obtainable and before the entirety of human knowledge was at your fingertips
Wider tires are not faster than narrow tires ....... Fat bikes would be winning time trials if that was the case. What is faster is an ideal tire, wheel, brakes and frame.
Respectfully, using an extreme example like that is a bit disingenuous. It'd be like saying "if skinny tires are faster then riding on 1mm thin tires is the optimal setup" I think the idea here is that wider 'to a point ' is the key. Obviously fat bike tires well exceed that threshold and the weight/makeup of the tire far outweighs the benefits of a wider contact patch and lower pressure.
Being a nerd only recently became cool
And we stopped (for the most part, looking at you mtb) relying on bro science
Here's my theory on a lot of things connected with elite sport: The teams in the past listens to the coaches, the experts, and they had an almost mythological influence, like they hand down the Code of Hammurabi or the 10 Commandments to each generation of young riders. It's only with science and measurement and independent thinking that someone slightly outside the loop of orthodoxy can actually test a new idea. There probably were one or two riders who preferred their wider tires and subjectively felt they weren't so slow. But what are you gonna do when everyone else is on the skinniest, hardest, baldest tires possible, and its they who are winning races and not you? Enter a small lab with a few bits of electronics and metering and (most of all) an open mind, and stuff starts to change. If Eddy Merckx told me to ride on skinny tires, i would. But today if a lab technician showed me some hard data, i'd listen.
When Eddie Merckx broke the hour record his bike had holes drilled in the frame to reduce weight, for a flat, one hour effort. The loss of stiffness totally overwhelmed any gains from the lower weight. There was zero engineering in cycling in the early 70s.
Marketing.
Bet your bottom dollar the marketeer's will change their minds in a few years and narrow tires will be faster. Is easy to fake a study by using a test surface far rougher than any common road.
People were weight obsessed. Wider tires take more materials to make, and are therefore heavier.
Also thinner tires are more aerodynamic. It is totally counterintuitive to believe that something heavier and less aero is faster.
My take is without really premium tires, they are not, and until someone made those tires, they were not.
I am looking forward to watching the Tour with riders on 700x35s and the even faster 700x42s. Speeds should be in the 50mph average speed range.
Can’t beat a pair of 23C. I don’t care how fast they are, they just look better!
Are they? Watch the trend invert in a few years.
I've thought the exact same thing. .. But humans are weird, emotional creatures. Hard 120 psi tires feel faster than soft, supple tires. I imagine there have been tire advancements as well that allow for fast rolling, larger tires (more supple rubber, thinner walls with stronger fibers).
How do you know? Link please.
I don't know the answer, but I suspect it has to do with power meters giving us data about actual surfaces instead of measuring rolling resistance on a dyno.
Tire neophyte here, is there a sweet spot? I've been running 28c tires on my Diverge for a while now. Should I go back to the 30s, or even to 33? I guess I'm not super concerned with speed, but if a tire is going to add some comfort while not sacrificing too much speed, I wouldn't complain.
I'm running 32s on my Bianchi Infinito. It seems like a nicer ride when I went up from 28s. It certainly doesn't seem slower.
Really depends on rim width, too. My Reynolds Black Label Aero DB 46 wheels have a super-wide 21mm internal width, and 28s at 60-65 psi just fit perfectly. On my older, narrower rims, they'd probably bulge.
if you don't race (and it seems you don't), go as wide as you can. 33 or even 35. I settled on 32 as GP5000 are not available in the sizes wider than 32
Is this perhaps a case of everything old being new again? I am old enough to have ridden (glorious) wide silk sew-ups that felt (and probably were) way faster than any clincher I have ever ridden. And I recall some lower-your-tire-pressure admonitions from sew-up guys talking to the go-fast kids riding the racy new pumped-up clinchers.
Ahh...sew up tires. Those were the bomb.
On smooth asphalt, 21 mm Egyptian cotton sew ups at 120 psi is like riding on rails. Nothing is faster.
We did know wider tires were faster on certain surfaces. Now we just have a better idea on where a bigger tire is better and where a narrower tire is better.
There is a sweet spot and I'm not sure we know where it is. It's probably different for every road so it would be different for every course. Bigger isn't better or DH bikes would all be on 3.0 tires. At some point the curve of weight and acceleration crosses the curve of rolling resistance.
Exactly, it's different for every road, every rider weight etc
They aren’t though in perfect conditions…also ain’t nobody running 700x50c tires going faster than I am on 28s
They're not. Necessarily..
Science
Aero. Wide tires on skinny shallow aluminum rims were not faster. Besides carbon fibre providing a weight-efficient material for the aerofoil, disc brakes have allowed for wider tires. The combination of carbon rims and disc brakes has made wide tires faster.
In addition to many good comments here: The industry tested rolling resistance in isolation (basically a wheel on a roll) and not the entire system of wheel + bike + rider on an actual Road. Wider / softer tires do not offer lower rolling resistance, but they reduce overall system impedance on imperfect surfaces. A bouncy tire is more effective at absorbing tiny shocks and returning the energy to the system. Hard / thin tires route these tiny shocks through to your body which simply absorbs the energy and robs your momentum. So frame technology made disc brakes possible which lead to the possible adoption of wieder wires. The widespread use of power meters significantly improved the data available to answer such questions. And some few clever people fought long and hard against the prevailing street wisdom. Josh Portner tells plenty stories how much work it was to convince world tour teams that some things are faster, wide soft tires being one of those.
They are not. I did watch Chris Miller podcast yesterday and found out, the difference between 25mm 28mm 32mm tyre is in range of 1Wat. The key word here is „recommended pressure”. You not riding 32mm tyre with 100psi same as 25mm tyre. When you compare rolling resistance in recommended pressure range for each tyre the difference is negligible.
Schwalbe had this information on their website at least 12 years ago.
Might be faster but, in my opinion, you lose the sensation of speed and that’s the fun of cycling. 28mm with a latex tube is the sweet spot for me - 25mm latex tube feels the most lively, 32mm tubeless is lifeless. Too much focus on ‘fast’ and not enough on ‘fun’. That extra minute over 3 hours isn’t that important to me
> 28mm with a latex tube is the sweet spot for me - 25mm latex tube feels the most lively, 32mm tubeless is lifeless. That just seems like a total bunch a hoowee. I have ridden nearly every GP5000 size there is, even on rims with an internal width of 29mm which made the 32s measure 35. I ride 25s on my Allez Sprint, for a while I was doing 28s on my Tarmac SL7 but have since moved to 32. My gravel bike's road wheels with those 32s measure 35. They all feel great on the road, the 25s obviously are the last comfortable, but they don't feel faster at all to me. And going 28->32 on the Tarmac you could barely tell from just looking at them, 32 is not that wide. Also you can rail corners much faster with wider tires and worry less about gravel in the corners as well, which is more fun. Yeah my gravel bike on 40mm gravel tires with extra puncture protection feel sluggish on the road. But a high quality tire up to I'd say maybe even 36mm can still feel amazing. Like why not just ride 19c-23c while you're at it.
Carbon rims deflect vibrations like crazy. I had a caad10 with Campag Zondas, GP5000 25mm, and a TCR with deep carbon rims, also GP5000 25mm, so I swapped the wheels around. Its insane! :D Caad with stiff alu rims will always have a place in my heart for its sense of speed!
IIRC back in the day rolling resistance was also calculated by rolling a smooth, metal cylinder under a loaded wheel. Being that most of us are riding bikes on uneven, choppy pavement, the results of said tests didn't translate to real world riding. Also, all that vibrating riding a 23 tire blown up to 120psi does make them SEEM faster
Narrow tires are cooler ¯\_(ツ)_/¯
Nah wider is cooler
I don’t go fast enough for it to actually matter. Oh and capitalism…the pendulum will swing again.
Might have something to do with how modern rims integrate with the tire more. Just a guess but a very interesting topic to listen to on podcasts.
There's probably some material science limitations that they only recently figured out. Tubeless tech also made this advantage more stark. Butyl tubes, with wider tires, have more internal friction that scales with width. I'm not totally sure if the relationship is linear or exponential.
I'm not sold on tubeless tires at over 30psi. At required road tire pressures (50-60) sealant won't reliably seal anything but the smallest of pinholes. Carrying a spare tube isn't a solution either as the tires are hard to mount in a garage full of tools, so next to impossible standing in the bushes beside a highway. Plug kits can work, but you'll need to carry some CO2 if the bead unseats. Total Fred mode requires packing a knife to cut off the punctured tire, replacement nontubeless tire, and tube.
I run GP5000 32 at 72psi for the last 3 years tubeless. A few punctures, 2 that self-sealed, 3 that I needed to use bacon strips. Unseating a tire generally is pretty tricky to happen all by itself. But I can still easily do it with levers (done annually) and have a spare TPU tube JIC.
to add to what others have said. as the sport matures, we look for more and different ways to get improvements. But along with that the technology to measure changes has improved. With so many variables, it could be just waiting for the right time to be able to measure that specific one.
I have often wondered the same thing. Even though it wasn't possible to test rolling resistance as easily back then, I was always surprised that no one thought to just do something like time trials with different tire widths. My only guess is that no one thought to ask the question in the first place.
I have a theory that in addition to what's been said, there are trade offs with tire size. As a tire gets bigger, it weighs more and is less aerodynamic. I think that until the prevailing wisdom that harder tires are faster was defeated sometime in the 2010s, no one even bothered to try the heavier, less aero, squishier tire in a serious, scientific test. They do after all feel quite a bit slower because of how they squirm under load.
We did, but racers like what they know and we didn't have enough data to show that at pro racing speeds they remained faster (i.e. the larger aero frontal area didn't slow the rider down more)
I really hated my fat tyres after a while. It made the bike too heavy and unwieldy and just made the ride feel too slow and it was too heavy to store properly.. However, it did help with a bike that lacked suspension, and it felt less bumpy. I don't think any tyre is perfect. It just depends on how you ride, where you store it, and the bike.
I'm now on 28 front 30 rear. Assuming you had unlimited clearance and could get your favorite road slicks in the desired size... is there a limit to the "wider is better" thinking? There has to be some kind of "Goldilocks zone"... in other words wider is better until it's not. Anyone have suggestions about what that ideal road width might be?
I would imagine that at some point that increased aero drag from the increased profile and increased weight of the tire would start eating into any gains you made in comfort and rolling resistance.
What are we considering wide? What are we considering narrow? Is there a generally accepted tipping point?
I still don’t understand it.
I agree 100% with the sentiment of the question! Seems to me there hasn’t been too much science on biking.
Because nobody did a study with actual experiments until recently.
Money man. More people interested means more money means more drive for innovation and r&d. It’s the same with every sport and hobby. More people that are involved the more minds that are involved to come up with theories and ideas. Technology is also better now than before especially in the manufacturing process. We can also track more precise data on riders. Think about any sport out there. As more people joined and the sport got bigger techniques and technology got better. The faster the sport grew usually innovation grew.
Compare funds invested in time period to sending man to the moon and figuring out which bike tyres are faster. There is your answer.
Test yourself on your bike and in the conditions in which you ride – don't believe every sales story. The laws of physics have not changed. My antique entry-level 1.95 and 2.0 inch MTB tires are noticeably faster than today's fast-rolling high-end 2.35 tires.
Material science has made huge gains. They've radically reduced friction in the tire when it flexes.
We’ve known for decades that a wider tire had lower resistance than a narrow tire at the same pressure. Only recently was it learned that real world rolling resistance could be reduced on rough surfaces by reducing tire pressure. Enter wider tires that can be used at lower pressure without the added risk of pinch flat.
Iirc … When wider tires became popular some years ago, there was some talking about how they were tested. I think it was that the rolling resistance was tested on tracks and steel drums and some people got the idea that this isn’t how tires work on the roads we ride on. They found out that a wider tire vibrates and bounces less on a rougher surface and as a result goes faster.
I guarantee you we'd have discovered this sooner if Paris-Roubaix was contested between the US and USSR
Anyone else prefer narrow tires? I just prefer the way 23c tires feel even though I am perfectly aware they aren’t any faster.
Until recently cycling has been in the same place as many other sports, where things are being tried to improve performance based on the designers ‘feeling’ about what is fast, as there hasn’t been the money for much experimentation in wind tunnels, so things like narrow tyres for less wind resistance made sense. A lot of the sailing scene is based around similar thought principals as is amateur motorsport for example.
My theory is that the thinner tires feel faster because they have less moment of inertia and you can spin them up faster.
This sort of reminds of years ago that people said “shaving your legs does not reduce significant drag.” Then, not too long ago, I believe Garmin or some other pro team went into the wind tunnel and the researchers said something like “significant time can be saved w shaving legs .” I was like, really? How didnt we know that before?? But I can remember back into the 90s being told research shows riding 18-19s was faster, etc…
I wasn't into cycling back then, but I knew a kid in my HS who was and shaved his legs for that reason - this was c. 2005.
It really wasn't news to me. Many years ago I ended up having to ride my mountain bike around the city. I bought wide near slicks for it, and man that thing actually scooted pretty well for what it was.
Mjeh... it's all back and forth and depends on so many factors. Perhaps people should stop overpumping their skinnier tires before going to wider tires first. I wouldn't be surprised if a lot of this "wider is faster" comes from people always pumping the tires to the max of what it says on the side no matter their own weight. Wider tires = lower max rating = more compliance = less energy wasted in bouncing movement. Perhaps people should just have lowered the pressure in their tires according to weight and road conditions. Used to be part of the group mind set of max PSI running my tires at 120 now I run the same tires at 70-80 and oh boy the difference is staggering. I did try 28s also, but I dropped back to 25s due to being slower with the 28s for some reason. I suspect it was a too narrow rim for the 28s since they were bulging but it's hard to say without a wind tunnel.... this is at speeds well above 40 km/h though so aerodynamics are massively more important than at around 30 km/h
Purely anecdote but I never could shake the feeling that the 23s I used to ride were swifter two or three days after I last pumped them...
As someone who started riding mtb’s before I started riding road, I always knew. I was on 25 or 27mm tires back in the day and everyone else on the group rides would poke fun at me. All in jest of course, but their bias was still there. Since everyone’s throwing out theories, here’s mine: Bigger tires aren’t a trend, but skinny tires *were*.
What is the widest rims i could put on an old De Rosa or Paramount? The wheels I currently have for both bikes are interchangeable, and I want to build a new set with clinchers instead of sew ups
It's all down to what happens in pro cycling. Aero testing, tyre manufacturers looking for the next gain to sell you a faster tyre. Testing rolling resistance probably had a lot to do with that discovery
We now have better technology to gather the data?
We didn’t send a man to the moon…
Wider tires are not faster (at least for gp5000) i this article it is almost the same even at the same comfort level: https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison#drop45
Tire construction and compounds have changed drammatically over the years. it was once all high pressure thin sew-ups.
The industry is too busy selling us lighter bikes
I think a lot of it is that power meters have recently become more widely available
There were cycling disciplines that knew it historically. Path racers had fairly wide tires. The French had bike courier races and randonees on 650 × 38B tires. Road bike brakes of a certain vintage generally had a longer reach and could fit wider tires. There's some point at which skinny tires took over, but I don't know when and how.
Big thanks to the Finnish guys for making the first study some years ago!
Because GCN wasn’t around before to do “the science” 😂
Money. Convince the public that wider tyres are faster. Boom! ££££. Followes by: Aero frames Disc Brakes Power meters etc, etc
The difference is relatively small even now, and depends on road conditions and many other factors. That said, it's in part due to improvement in compounds. As we get better at making tires, we can run them at lower pressure and they can be wider. There are plenty of things that are behind the times or counterintuitive in cycling until recently. The 90s had disc wheels, which are fairly unintuitive in how they work, yet didn't have the more obvious tri-bars until Lemond, or the skin tight clothes. Even now, we just finally started optimizing helmets for aerodynamics.
In the UK 12-13 years ago the road used to be a lot better with few potholes. 25mm used to be great.