Cycling Myths: Wide tyres roll faster *because of a fat contact patch shape* REALLY?
Vložit
- čas přidán 7. 06. 2019
- We address the belief that wider tyres are always better, that wider tyres are faster *because of contact patch shape*. Is this really true, on all surfaces? What is your opinion?
SHEETS
fft.tips/pressure2
fft.tips/tyre2
fft.tips/surface2
LINKS
fft.tips/feedback
fft.tips/strava
fft.tips/patreon
fft.tips/facebook
#widetyre #contact patch #CRR #rollingresistance - Sport
If you want to know what size tyre on which surface watch our follow up video here fft.tips/vsurface. Ps pls join us on fft.tips/strava and/or fft.tips/patreon thank you!
Done, but you forgot to add tire model and possibly an option for new and stretched tire. The cotton sidewall vittoria corsa speed have stretched 2mm during their life time with me (which wasnt very long, 2500km)
@@ericoschmitt thank you!
@@ericoschmitt that is quite a bit!
If you want wider tyres, keeping your old ones might be a cheap option then ;)
@@ojanssensande except one had a cut in the last ride and the other had holes big enough that the dry sealant would unplug and reopen if pumped above 80psi... They are a bit faster than gp5k but too fragile, I gave up on them.
I guess that has to do with cotton sidewall, I bet conti tires wont stretch much.
I use Continental touring 25 mm tires
Bicycle tyre manufacturers, claim that at the same pressure, a wider tyre roles better than a narrow tyre... but no one does that. Narrow tyres are usually pumped to much higher pressures, than wider tyres. This will automatically reduce the contact area of the narrow tyre and subsequently, the rolling resistance. Narrower tyres are also lighter, requiring less energy to accelerate. In conclusion, there is no doubt in my mind that the narrow tyre, pumped to the correct pressure, is faster than the wider tyre.
The major mistake in your assumption is saying that the greater deflection in the narrower tyre compared to a wider tire at the same pressure means that the wider tire is going to give a harsher ride at the same pressure. This is not correct.
The static deflection (say 5mm for a 23mm tire and 3mm for a 32mm tire) is only to support the weight of the bike and rider. The tire has to deform (compress) more for the narrower tire and this is why the rolling resistance is higher. BUT, this is compression to support the weight of the bike and rider, not compression due to hitting a road imperfection.
If you imagine the peaks from each stone in a bitumen road surface that are in contact with the tire, each peak is contacting and locally deforming a part of the contact patch and in this case, the local deflection will be the same because the deflection is in relation to the contact area of the local peak (not the entire contact patch) and if the pressure is the same in both tires, the local deflection will be the same and the tires will feel the same harshness.
On a rougher surface, lowering pressures will make both a narrow tire and a wider tire faster but the benefit of wider tires is that the pressure can be lowered further with less likelihood of pinch flats or rim damage.
I think this is true, but it also depends upon the kind of obstacle you are hitting. For the small stone that create surface roughness in the road, it would seem you are right, but imagine hitting something like a stick or bump, where your entire tire is momentarily on the obstacle. The wider tire will deform less at the same pressure. That is to say, any obstacle that is at least as wide or wider than your tire, a narrower tire will absorb it better, at the same pressure.
So yes, you might get more buzz, or high frequency vibration with a higher pressure tire, but the shock absorbtion is a combination of the section width and pressure.
Another mistake in your assumption is that "because the deflection is in relation to the contact area of the local peak (not the entire contact patch) and if the pressure is the same in both tires, the local deflection will be the same and the tires will feel the same harshness." You must also consider the load applied. Obviously the more points the tire is contacting the ground, the less loading at any one point, and therefore less deflection.
Another major flaw in the thinking is... if go to 2:20 of the video and look at the defection image.. look at the edge of the contact patch and the angle the tire carcass need to be bent to achieve the contact patch... the wider tire does less bending of the tire carcass to achieve that contact patch.. less bending than the thinner tire means less energy lost as heat than the wider tire.
a) you can think of the wider tire starting out more flat than the thinner tire.. so less bending to achieve that contact patch...
b) the sides of the contact patch of the thinner tire will closer to the sidewalls and closer to vertical so will require more bend to get to horizontal to achieve that contact patch...
Wider tyres have "better rolling resistance" because they absorb imperfections better. I agree there is no difference on a perfect surface that almost never happens outside a velodrome. This has been my understanding since 2013 when I did as much investigation and pondering as I possibly could on the topic at the time.
Double thumbs up
no sense for statements: if better absorbs imperfections then it absorbs more energy so it has bigger drag
You must live Ina third world country if the city pavement and sidewalks are like that. Well in cases like that, like in poor countries the roads and sidewalks are so bad that people commute on MTB's
Where I live though 99% of my commuting is smooth and perfectly well suited for 700 x 23 or 25. But I personally prefer x 28 or x 32 for commuting
@@makantahi3731 No it simply absorbs opposite force vector and those create drag!
@@MybeautifulandamazingPrincess I call bs. London roads are awful
I’m afraid that you have misunderstood what those tyre manufacturers are saying. That add doesn’t say anything about the contact patch area. It all about the shape of the contact patch. Wider tyre has shorter and wider contact patch which means less deforming of the tyre. Less deforming means less work being done in deforming your tyres. Less work means less rolling resistance.
Dude, this really helped me put deal with the whole concept of a wider tire, which, in my situation, I need a softer experience in urban bumpy. Many thanks
Nice video! Takes most of the myths with good explanation! Same rolling resistance (with the different sizes/pressures) but also indeed the fair point of aerodynamic losses of a wider tyre at higher speeds (such as a time trail)
Experience says, perfect road=23, all road mixed 25, rougher roads 28.
It’s way more complicated, factor comfort, speed, surface, pressure, weight, etc.
I have 25c clincher, tubeless and tubular, 28 clincher, 38 tubeless, all are highest end and ride great, in my experience for most road 25c Corsa tubeless is fastest of all I have, but it’s still complicated 😊
Interesting...I just bought couple of 32s, cycling is about joy and comfort in riding, it’s not about racing. High PSIs makes the tyre so hard that normal road bumps makes your body absorb so much shock that after 20mile I start thinking when will I reach home and I ended up taking too much breaks. With wider tyres and lower pressure, I enjoy the ride quality even on longer 3hr rides and ready to ride again the next day :)
I’m riding on 32c and I enjoyed it very much
@@csplau I’m riding on 40 and hate it it’s to slow especially up hill
@@brianhancock9409 oh ok! I’m riding on GP5000 28c now and it seems the rolling speed is faster!
I have got a trek domane with 25 nice fast but I have got cube Nuroad ex that I wanted for winter but that’s got cube Alex ra 0.8 cx 21 inside rims with 40 tyres I was wondering what was the thinnest I could get on my rims some people have put on 28 which is what I whant
Things are way more complicated than just the patch. Rolling resistance isn't just the patch but depends on the surface as well. Generally you can use higher pressure when the surface is smoother. Pro Teams found out that you get the best rolling resistance for Paris-Roubaix when the rims is just preventing contact. There is a video here which showed that to much pressure was even worse than to low pressure IMHO by a factor of 2 or 3. The explanation was that jumping up and down also consumes energy where a tyre with lower pressure would deform over the bump.
There is certainly a sweet spot for tyre width but just pumping up small tyres will not make you faster.
Explored in detail on the Silca blog, including measured radial stiffness of different sized tyres at varying pressures. Included in that was the observation that a 23mm tyre at 7 bar is still stiffer than a 28mm tyre at 6bar.
Thanks you. This is the explanation of what I experience with my 5 bikes.
join the club, 23 is faster but harsher
One of the reasons why wider tyres are used on modern carbon/aluminum designed bikes compared to older designed steel frame bikes is simple, the speed loss is more noticeable in it's measurement due to the ever increasing specialization in bike design - gone are the days of generalized bike design of purpose use. My current criterium and cyclocross bikes have profoundly different tyre widths as standard but when used for there designed purpose the speed effect is fast!
I had to get into bike design theory a fair bit when I made a full on custom disk wheel time trial bike in the 90's. That bike ended up with the tyres of 19mm front & 23mm rear just to get the correct ride handling and feel, a bike with uncomfortable tyre feel below 30 kph but sure as fast above the 30kph point and comfortable tyre feel & speed.
The shape of the contact patch and how the tyre is constructed has way more importance on speed effect than most would give credit too! A very good point of reference would be the Michelin Pilot Road tyres for motorbikes, I've used all of the generational stages of these tyres - I'm currently using the fifth generation on my high powered motorbike and the speed effect increase has been staggering. Lets just say the what I now consider normal speed now with these tyres would have got me killed on the first generation of these tyres, on set type of corner, same weather conditions, etc and lets not forget that the tyre width & size & recommended tyre pressure for my motorbike have not changed one little bit - what has changed is the shape & construction of the tyre!
The whole thing with speed effect loss or lack of it comes down to the bike design with the correct tyre width to match that design, you will feel the effect increased when combo isn't correct - a mm here or a mm there in the wrong place can make a huge difference when combined. Getting the frame design done for that custom made time trial bike I made was the easy part, getting the tyre width sorted properly was the pain in the back side bit!
If our roads were theoretically smooth, 23c at 120psi would be perfect but it is not so . . .
no data here, only what my butt says.
The arse is king no matter how many claims from various endless sources 😭😂😅
Thank you for this. Even without a great understanding of physics, it always felt like a piece of information was missing when the various other youtube cycling channels made their case for wider is faster. And I think it was the psi/bar difference from width to width that maybe they just "assumed was understood" by the public?
Where do I find smooth surface and zero yaw?
all to do with the asphalt condition, 28s absorb the tiny imperfections on the road surface better than 23s thus making you go faster.
contact patch shape only matters if the asphalt is silky smooth , 23s will be faster then because of the higher pressure.
long story short the wider the faster on country roads, the skinniest the faster on city roads.
my 2c
Exactly! If you ride crap roads then a bit wider will be faster
I agree, I ride on mostly bad roads, have rode 28's and they're nice. Yet if you're really wellying the bike, then a 25 or 23 is better as less deflection...
Comments based on my experience. I have ridden 23 for more than 2 decades, because that was all that was readily available. The past 3/4 years it was 25s....and recently all I ride are 28s. Agree that over rough asphalt the larger tires feel better, but one thing is for certain, I can corner with much more confidence , speed and bike lean on 28's.
what city do you live in??? you have paved, smooth roads there?? really?i'm going there.
Toronto has "paved" roads in the sense that there are chunks of pavement loosely connected together with sticky tape and glue, but actually paved? Not here.
in Toronto, you really need a mountain bike with a full suspension system and the widest tires possible
You have a great point. It's exactly the reason why I ride 25mm tires on my road bike, and 21mm tires on my track bike.
Excellent video that represents my riding experience over 40 years, 9 bikes, and well over 100,000 miles of riding.
If you're riding on rough roads, or are heavier, or want a more cushy ride, sure, wider tires can perform better. But the blanket statement you hear everywhere that "wider tires are simply faster, here's 'scientific' proof'" is indeed a myth from my experience.
¿You've had nine bicycles in just over 40 years?
On my hybrid/gravel bike I went from 30mm Kenda Cyclocross tires at 70-85 psi, to 38mm Kenda kourier tires that are 50-85 psi. The extra control and dampening on the coarse pavement and gravel roads here was night and day. I believe someone made an app for road surface/tire pressure that optimizes the pressures for the front and back tires.
surely u would have different pressure in a 23 and a 28
I change my pressure with about 5 psi per 2mm of my tire
if you ran the same pressure you might as well be riding on your rim eventually.
He actually says & shows that in the vid
Didn't you basically conclude that wider tyres have the same rolling resistance and more comfort, for a tiny theoretical aero penalty (important for the large percentage of people riding around at 40 kph average)? If so, I agree, which is why I'm riding 32s year round....
Enjoyed the video and it makes total sense I am of the view that tyre manufacturers are overly simplyfying a complex subject with many variables into a single variable approach for the relatively easier consumption for the typical consumer.... A lovely road surface such as track rising and skinny tyres rule. But for riding on the road....? What is best?
The reality of riding a bike on the road is facing the reality of "bad conditions" or the reality of impedance loss. (Alex you make this point yourself) Anyone can feel the difference in speed when the surface changes, I know I can, each and every day I ride my bike. It is to this end that the wider tyre question becomes relevant in real world cycling. But how wide??... I'm still stuck with that question....
Intuition and a splattering of articles read suggests a 25mm rim width matched to a 25mm tyre and tubeless is the best balance of aero, rolling resistance (real condition with impedance losses), and the absence of losses due to inner tubes... The question of tyre choice is pretty massive in terms of the variables involved... I am yet to come across an holistic guide to the same. My 2p..
Now.....If only I could get past a whole load of irrational concerns relating to going tubeless.
I noticed the same issue while perusing the Rolling Resistance website. The other very important factor you mention is mating the tire width with the rim width. I have an old 9 speed Klein with, by today's standards, skinny rims. Furthermore the frame spacing does not allow a tire of 25mm. In any case the more important factor is the aerodynamics of the combined tire and rim. That is, you must pick the tire width that fits the rim. That's why the move to wider tires necessitated making the rims wider. I really enjoy your videos and scientific analysis of the topics. Has anyone done a real world test with a power meter comparing the average speed and watts for the same rider and bike comparing wider or narrower tires/rims to show if there is a net benefit? Thanks again!
My gravel bike came with 650B 47 tires that are really nice for riding in gravel and in the woods. My bike allows for up to 700c 42 tyres. I am also planning to use the bike for road cycling without gravel. What would be the benefit, if any, of having an extra pair of wheels with 700-30 or 32 tyres for strict road cycling?
I believe everything you say in the video is true. However, I'm glad I changed to 25mm from 23mm. The increased comfort and better 'feel' of the 25mm is worth the small theoretical speed benefit from the 23mm.
How did you measure comfort exactly, or was this placebo. We all know that 'feel' is so utterly unscientific and so many are saying one thing on the basis of confirmation bias but there is no change whatsoever and is simply inthe persons head.
@@ynotnilknarf39 I agree there is a lot of nonsense talked about comfort and road feel, especially when debating various frame materials. But I think tire size (and therefore inflation pressure) is the one thing that clearly does make a noticeable difference. Especially if the road surface is not ideal.
@@ynotnilknarf39 From now on I'm going to refer to my saddle sores as placebos.
In my experience, 23s slow you down on rough roads. 28s, while feeling a bit heavy, will sail over rough pavement. So I ride 25s. I see it as a compromise. Not too heavy, not too rough, and all of my PRs have been set on that size tire.
but on really smooth tarmac you are better off on a 23.... and with strong headwinds ...............
@@sylvainbernaers 23 front 25 back is a good combo
Roads are shit lol 25mm or go home lol 23mm and lesser is for indoor track riding or time trail tracks where faster tyre is needed but yea I think ile stick to 25mm road tyre 23mm is more a track tyre
Just a headsup to everyone researching tire science. For the most part, the tests conducted on tires are under controlled conditions (using rollers), that do not typically resemble real road conditions: Large road cracks, varying asphalt aggregates' coarseness, wet/damp conditions, repair patches, concrete sections etc. These changes can substantially change the observed dynamics where tires experience large shocks or drastically change tire hysteresis.
Rolling resistance as measured by the tire manufacturers on a drum is far from the whole story. You raise some interesting points. There are so many factors in play that we don't fully understand what is happening. I agree with Ken Mourn, who commented yesterday, about suspension losses.
Alex I have a question . I have knobbies tires on my 26inch wheel mountain bike . The knobbies are 12 mm in length and width and 10 mm apart . When I'm riding on the road I add more pressure to the tires so only the center most section is touching the road . When me and my road bike riding friend start off on a black top hill and neither one of us touch the pedals I can get to the bottom of the hill faster than his racing road bike with the skinny road tires . My bike weights more and I weigh more . Is it the weight that makes me go faster down hill or is it because I only have 106 12 mm patches of rubber touching the road in one full rotation ? Would you do a knobbie tire test vs a solid rubber tire .
I like this one, a couple of other things to consider. Most of the bicycle are pretty close to a perfect spring, it gets deflected and it bounces back with very little energy loss, except for the tires: the deflection of the tire carcass absorbs a lot of the tire (the air inside is a good spring). As a cyclist we pedal (and may be I am the exception that I am not electric motor smooth in this), and the power strokes deflect all those springs, and they bounce back at the end of the power stroke, but the hysteresis of the tire carcass absorbs some of that energy, fatter tires at lower pressures deflect more and absorb more of that energy. That is why I think that skinnier tires not only feel faster, but are faster. Secondly, those fat tires do grip better, because as the vertical load on a tire increases the cof decreases so a fat tire will grip better, this is used in setting up cars to varying degrees of understeer.
The contact part of the vittoria Robinho pro when pumped to the recommended psi of 130 is about 5mm. There is a narrow puncher resistance strip in the middle of it and if you only pump it to 100 psi so that the entire surface meets the road, you’re almost always going to get a puncture. What a trick.
The industry has to tell us something to get us roadies to come around to using wider tires with less pressure because they want you to buy tubeless tires. Narrow high pressure tires don't work so well as tubeless. I don't understand what is so bad about using tubes. Maybe it's just the industry can make more money by selling the tubeless rim tape, sealant, high pressure and high volume pump gadgets, tire plugs, etc. I've gone back to using narrow 23 and 24 millimeter tires with tubes because it's just easier to deal with. And they roll just fine.
Hi there,
When talking about rolling resistance (and comfort), there seems to be a confusion in energy loss due to micro deformation (tread) and macro deformation (sidewall).
The surface type needs to be taken into account, and is key to any kind of analysis!!
What like this fft.tips/surface ?
Hi I am going to be buying a new trek fx 2 disc hybrid bike in the next two weeks. I am going to be upgrading my wheels to a set of dt swiss rr421 asymmetric rims . I am going to be running a set of schwalbe marathon 700x35c tyres. The rr421 has a inner width of 20mm is the 20mm inner width rims the best option to get the best proformance and ride quality out of the tyres. Or is there a better rim width I need to consider to get the best proformance and ride quality. This bike is be used on ashfault roads and city streets 100% of the time. Can you please tell me what is the difference between a asymmetric and symmetric rim. I do know care to pay the difference if the asymmetric rim will be my best option also. Thanks for reading my post. And all the info you can give me would be greatly appreciated.
THANK YOU 😊
What size tyres and psi do they in general use for a rider weighing 70kg in the `paris - Roubaix race ?
Interesting topic as always Alex. Like so many, I have played around with the application of various tire widths over the past five years in response to the new convention that wider tires w/lower pressure is faster the rougher the road conditions. I have settled on 25mm rear/23mm front @85-90 psi for a 75kilo rider/bike combined weight as having the best overall ride characteristics of speed, comfort, grip based on subjective feel.
Now I wonder if you can do some scientific comparisons on the relative benefit of riding heavier “flat resistant” tires (ie Conti Gator Hardshell) vs lighter faster tires (Vittoria Corsa) in real world road racing situations, given that most of us will be out of a road race for good once we get a flat tire...
I have 27mm25mm tubulars on my carbon wheels, I'm usually around 95kg but have them at circa 85psi front and rear, tbh I find this somewhat a bit bouncy on certain bits of the road but pretty good on some of the better A roads or where Mr Highways has accidentally done a proper job and the surface is actually smooth!
I used to ride 22mm tubs (and in fact commuted and did some light 'gravel' riding on 23mm in the late 80s, through the 90s and up til around 2008 I was still on 23mm (Vittoria Rubino Pros)
Now I ride 28front/32 rear on my commute/utility bike both folding tyres) and tbh I don't perceive to be much difference to when I was riding 23mm. Maybe the roads are worse overall now. Interestingly, I do a regular 10 mile trip, and on my drop bar audax bike with fairly fast rolling tyres, the same tyre size and pressures on my hybrid get me virtually the same time to complete. The hybrid is one of the best that was ever made and is carbon excepting the main triangle and chainstays, the bars, forks, seatpost all carbon (and the frameset of the audax bike is identical in all but being one size up). but I honestly thought I'd be slower.
Will need to do more runs with the hybrid and I don't have a watt meter but it's a tad strange as to how they are almost the same.
Great video. Quite a complex subject although really relevant.
Hard to judge because so many variables with tire pressure and tire construction, and you don't simply ride them at the same pressure. I've done a lot of riding on 23,25,28 and 32c. Like 25c the best for smoother roads, don't see any reason to use 23c. 32c feels quite a bit slower but I have them at 60psi and they are a bit tougher for my commute. 28 feel almost as fast as 23 & 25, but that was on the CX bike which will be a factor compared to my road bike.
Steve Co bombing down mountains on 28's is SO much fun. Grip for days!
can anyone answer, what size rim width will i need for 26x2.35 tyres
Thank you, I've been thinking a lot about these question. Please humor me.
Regarding the first 50% of the video and the myth referenced in the title:
The tire manufactures are mistaken (as you showed), but roadie meta now says "28 at lower pressure is more comfortable than 23/25 and just as fast". In other words, the people I hear aren't saying 4:37; They're saying 8:21 -- what you called "the headline".
Ironically, then, this video is more about confirming roadie meta!
The biggest myths regarding contact patches and tires are the ones you casually busted in the second half of the video:
(1) Wider tires = bigger contact patch (without reference to PSI or load)
(2) Bigger contact patch = more grip (in-and-of-itself)
(3) General ignorance of CoF
Reality seems most understood by car engineers, partially misunderstood by motorcycle enthusiasts (they still think wider patch = more grip), and wholly misunderstood by cyclists.
I believe the misunderstanding comes from these sources: [Please confirm my understandings!]
(1) In less-than-velodrome conditions, a lower PSI provides a suspension effect, granting efficiency and speed (the point of suspension) [And perhaps the tip of an iceberg barely explored in bicycling because of its practical difficulties]. You started to address this at 10:15 and called it "smooth" and talked about impedance loss but didn't go all the way to confirm the suspension effect.
(2) Additionally, in rough conditions, a larger contact patch (or two, in the case of the MP3 and Niken) "finds grips" [my wording], much like a 4x4 rock crawling jeep or enduro motorcycle with ultra low PSI, providing efficiency and speed (compared to bouncing/slipping/crashing). [If you want manufacture myths and to see Amonton roll in his grave, examine the claims for the MP3 and Niken: "Twice the contact patch = twice the grip!"]
(3) Sport (and dirt) motorcycles use a wider rear tire (where massive power is delivered) compared to the front [This one baffles me. Is it because of tire load sensitivity? Cornering profile?]
Accordingly, casual experiments by MTB enthusiasts (rough trails, less aero) are showing clear benefits of 2.8 tires (with lower pressure/"tension") vs 2.1. The "Why" isn't understood but I suspect the key is suspension.
Thanks for letting me organize my thoughts!
Thank you Jason for watching my video so carefully.....you have helped organize my thoughts on this topic too! I am doing some more tyre videos soon and you have helped no doubt! Regarding big tyres on rear I can think of 3 reasons in motorbikes....powertransfer / grip whilst cornering under power and cooling....they all probably require a big wide tyre on the rear of a motorbike. What do you think?
That's wonderful to hear. I'm flattered. OK, my guess is something to do with power, but the questions is, why isn't CoF the sole determiner of power transfer (and therefore contact patch size irrelevant)?
I found a blogpost by an engineer that starts off confirming my beliefs and argues that cornering behaviour is the issue:
simanaitissays.com/2016/01/10/wider-tire-bigger-footprint/
But, despite claiming that drag racing tires are tall and skinny (compared to what, I'm not sure), says that they run at low psi for the sake of footprint! And this is right after saying that a narrow long patch is better for straight line speed! After that, he talks a bit about F1 cars cheating with low psi. This is the same in MotoGP (minimal PSI rules), but the question it raises is "what advantage is gained with a larger CP (and wattage loss, presumably) on a mostly smooth track (with vehicles with high sprung/unsprung ratios)?"
I listened to an interview with the Vice-President of Engineering at Bridgestone Firestone about motorcycle tire myths and recommendations. Good stuff, but never quite explained the rear tire thing.
adventureriderradio.com/adventure-rider-radio-episodes/2019/4/11/trouble-in-panama-spencer-conway-answering-tough-motorcycle-tire-questions
Interview starts @ 33:53
Maybe he'll respond to emails? :)
@@jasonjayalap excellent info and links; if you find anything else pls let me know on info@fastfitness.tips
I saw a motorcycle video explain narrower front tires a fitted to racing motorcycles to minimize the effect of unsmooth surfaces on the steering/handling. A wider tire would have more leverage to transfer forces to the handlebars (steering).
All I know is Cannondale, with the release of their first aero frame, found in their testing a wide rim (20mm inner width), paired with a skinny tire (23mm), offered the least rolling resistance and cut thru the air better than a mushrooming 28mm. I put this theory to practice with my new Roval CLX64 's. They feel faster, are a tad wider (20.8mm) than Cannondale 's Holograms, can't tell any difference in the ride, but don't feel as 'planted' on the pavement as I do get blown around more easily
I have been wondering this, thank you for explaining!
Is it of any use to evaluate the differences with hoop stress held constant?
Great video. I also wonder if tyre deformation percentage contributes to rolling resistance. 5mm on a 23mm tyre is more substantial than 5mm on a 32mm tyre. But yes, i could see the possibility that manufactures got together to think of a new way to get people to buy bikes to replace their bikes with smaller tyres. Maybe in 10 years we will see the trend reverse back with some new "scientific understanding". I get the feeling we have probably been here before sine pro cycling has been around for 150 years.
they just make us buy tyres and bikes.The rest is fantasy
what tyre faster losse preshure ower year, wide with low presh.
or narow with hight presh.?
Assuming the valves are the same, the lower pressure tire will lose less air.
Great video! I always thought they were using same pressures across all tire sizes to favor their desired outcome so they could say "see bigger tire rolls better". People need to perform their own tests and choose harder and faster or softer and slower (on tarmac I mean). I fell for this low pressure bs and ran 75 psi in my Contis gp4000s 28mm(actual 31.6mm) for a few rides and my avg speed dropped by 3 km/h on flat fast rolling bike paths. After that I only run 95psi. I'm 87 kgs plus 11 kgs bike. I admit that it was more comfortable on the hands and arms at lower pressure so to solve that problem I installed a pair of very soft foam grips and could not be happier. Each thing has its place. Hard tires roll faster on tarmac (eg ask skateboarders if they like soft wheels, answer is no because they're slow), and soft grips isolate your body from all the trepidation that you may encounter on rough patches of deteriorated asphalt.
I spent years trying different size tires and what i have learned is that wider tires are more comfortable. They can be faster if they are equally as light. Usually wider means bigger more weight more metal rubber etc therefore wider tires science is great if you can afford it. On the other side 23c is lighter and I find to be more versatile for what I need and want them for. I feel like the weight and aero of 23c helps me save energy. I have a 32c bike that runs high pressure and sure it rolls just as quick and it's more comfortable but it weights and makes me more tired.
Well argued. I'm a big fan of schwalbe pro one running them at 60 psi front 65 psi rear on wide stans avion rims ( 21.5mm internal) . I'm not a racer but enjoy the comfort on the c and d roads we mainly cycle on. Big tyres give comfort without loss of speed. Tubeless helps with less punctures.
Great. It would be nice to completely understand all of this. This is a start. Thanks.
Respect. Very good video. Narrow tire with high pressure is rigid. Good power transfer, low air drag area(same rim wide) and light. Wide tire with low pressure is stable. Comfortable for bumpy conditions, more stability area. Better is nothing. Different choose for different conditions. Totally had more different bicycle types for better performance(Road, mtb... etc.)
Admittedly I have changed several things. Gone from 19MM rims to 25MM rims. Gone from Vredestein Tri-Comp to Continental GP 5000. Gone from 120 PSI to 75 PSI. Gone from 23MM tires to 25MM tire. My overall rolling resistance is quite noticeably less in my current configuration.
so now you go with 25mm rims and 75 psi, is that correct? clincher, tubular, or tubeless?
+1. Great video. Usually when a position begins up front with "ignore the lab data" and instead focus on subjective experience you've moved away from science into witch doctoring.
Your analogy of the spring is perfect. This analogy also makes sense to road absorbing effects of a rough road..so i believe a 23c can still perform as well as 28c at the right pressure. I only see the 28c better on slower roads and slower average speed courses because the effect of aerodynamics drop off at lower speeds ....such as climbing and cobbles etc.
Richard Vitiello bombing down mountains on 28's is so much fun. They feel like you're on rails.
If you have a very textured road then a thin tyre might have to descend and ascend more than a wide tyre, causing greater losses. This too is part of the physics.
This is what I have always thought: The walls of a race tire is not rubber, and if compression reaches the walls, a lot of hysteresis energy will be lost. A wider tire will have the compression in the rubber area simply because there is more rubber there (width). Rubber will give back energy at the back end of the contact area, wall material does not.
There is also another myth you might want to bust, and this is that the latex tubes have less friction against the tire. My view is that latex tubes has less hysteresis loss than butyl tubes and springs back with less energy loss. The latex tube, as well as the butyl tube, is so hard pressed towards the tire that they form a unified object. Imagine a ball made of butyl, wall material and latex and drop them from a specified height. Latex has a 75% bounce. Butyl would probably not reach above 40% and the wall material would not even reach 10%.
Nice try but your guess is simply that. A unified object, well in your mind that might be but let's some proof. As for a wider tyre giving energy back, where is it giving energy back to, in what form is that energy being "given back", vibration, heat, noise?
how much energy, under what condition, what mass of rider or mass on tyre/contact patch.
You're making totally unfounded guesses as to 'bounce back' with no science behind it whatsoever.
A whole load of hypothesis with zilch in the way of evidence
Great Info. Thank You
Your right in a perfect world but 10 mins in you finally mention surface roughness... This is why we race on the boards (velodrome) on 18 & 19 mm @ 130+ psi(tubes). when TTing on good roads I use 24mm @ 100-110psi (Tubes) but on the crap roads where the tour down under is raced we use 25 & 28 @ 75-90psi(tubeless).. Isn't it about the right set up under the conditions which you ride.. I've seen old video of rolling resistance testing where the drum is smooth but if you look at most the newer test rigs the drum looks like checker plate. if you want to prove narrower tyres have lower rolling resistance (with the same air pressure) use a smooth drum and rig... If you want the prove wider tyres have the lower resistance use a rough drum/rig. As the end user we still have to work out which width we can make work the best in our environment. good work on keeping people thinking so they don't get blinded by marketing and options. "listen and evaluate"
When a tire hits the road it has to change from round to flat. To do this the rubber compresses and then expands as it leaves the road. A longer patch (narrow tyre) needs to compress and expand more as it hits, goes flat and then leaves the road. My 2c
This is one of the better explanations I have seen in the 4 decades of battling marketing-based theories of CRR and tire section. Even some of the brands mentioned have stated clearly opposite opinions 20 years ago. The story is much more complex and nuanced than he explains in this video, but he only has so much time to explain this and it is very complex stuff.
I use 700 x 28 and x 32 tires on my commuter bicycles (the upright Dutch bike/vintage European style), with gravel treads for adherence on dirt and sand cause I live near the beach).
They're pretty good for commuting because they absorb impact like when you need to climb a curb or something, and at the same time aren't sluggish as MTB tires
I used to commute on a vintage MTB with 26er MTB tires and once I tried 700c wheels and road and gravel tires the difference is night and day, the MTB tires feel horrible to me now to commute on. I still own the bike (a 90's GT Karakoram) and I converted it 700c or a 650b set when I want slightly beffier tires, it's working great and I don't minded the slightly higher bottom bracket, I'm used to it. It's much better too than 29er MTB's because it's way lighter and more nimble. I'm never gonna commute on MTB tires again unless I'm cycling through the wilderness or something (I live in Hawaii btw)
On my road bike I run 23 or 25 and they're great for road
There are a lot of variables which tire is the fastest in different cases... In my area wider tires are getting better because the roads are getting worse and worse. If there are a new perfectly paved roads, the thinner tires with a lot of pressure are the fastest. But this is rarely enough. If you ask me, which tire I would recommend for here, my answer would be ~26-28mm, with 4 to 6 bars, depending on your weight...
Is it 700c×23c×13k×23mm tires are best or some what best
well i'am 1m68 for 71kg.My the bike i'am at 85kg I have 23mm tire at 115psi ( The Bontrager R2 tire) Should i try lower pressure tire?
So smaller tire better when you live in Monaco in perfect weather and roads, wider tire better in the real world.
Yup:-)
Works for Mallorca too
Hallelujah. I live in southern California there's a trail called the Pacific electric trail. It has smooth roads it's amazing. I suggest any of y'all out there with the road bike who want to ride on a nice trail check it out. Thank God I have 23 mmmm hoping to bump up the 25 which I believe will be the perfect for that road and other a little rough roads that Jesus Christ for fresh air for the sunshine. Jesus loves you may he bless your health
Call it Lanzarote roads
Yup. On the track go with the narrowest tire and the max tire pressure. On real roads, it depends on how smooth the road is and weather conditions, plus rider weight and other factors such as aerodynamics (a wider tire has less aero than a narrow one). Genuinly on the roads a 25c tire is best maybe for a tt a 23 on the front and 25 back but that is mostly on good roads (I would suggest go with 25c always because they are comfy and fast and on a long road race comfort makes more difference than on a short TT)
Doesnt sidewall deformation vs tyre width also play a role? I mean that the sidewall of a more narrow tyre has to "fold" more sharply than a wider tyre.
Also is there a difference in spring progressiveness between narrow an wide?
I tried 25mm a couple of years ago and reverted back to 23mm. Felt best for me. I concluded it’s probably a rider weight thing. I’m less than 60kg so can lower the pressure on a 23mm until I get the desired comfort/speed without the risk of a pinch puncture. Also I run Zipp 303 and Zipp recommend 23mm for the aero benefit. Why pay for aero wheels then throw away the benefit by fitting wider tyres.
Vittoria Corsa / latex tubes and ride on all sorts of road surface.
It depends also on when your wheel was made, wheels have got wider to match the wider tyres. The current generation Zipps are 26.4 external and were designed for 25mm tyres.
"The Zipp Tangente R25 Road tire is a perfect match for this wheelset to deliver exceptionally low rolling resistance and high cornering grip."
zipp.com/wheels/303-firecrest---carbon-clincher/
@@blorg8206 Mine are 2 year old NSW 303. Certainly 23mm is as wide as you'd want and at the time the Zipp recommendation was for 23mm. As I understand it the tyre width needs to be less than the out side rime width for best aero results. As both Conti GP4000S2 and Vittoria Corsa G+ come up larger than stated on these wheels I find 23mm measures more like 24mm and is just narrower than the outer rim width.
3:00 how are those dimensions derived?
Doesn't it depend on what kind of bike is being ridden? E.g. wider tires may be faster on single track because of additional grip. For example, if I rode my cx bike over slippery roots, I'd probably be slower than on my 2.35inch 29er xc mtb. Would higher volume tires also be less fatiguing?
One question: Dose a radically wider tire put more pressure on the rims and spokes, in turns and such?
Less
I've used both thin and thicker tires in my experience I've found that the speed is about the same. It's stability that is different. A lot depends on road surface personally I prefer 25 mm on both my bikes. It's a bit of a compromise between the two of them but it's absolutely nothing to do with speed. I'm normally faster on the road bike than the hybrid because I ride on the road and have a lower position on it. Not anything to do with tire width.
Ive run 25 and 28mm tubeless pro ones. With 85psi in 25 and and 75psi in 28s. Both feel the same in speed but the 28s are just more comfortable and feel better cornering
agree the same for 23mm vs 25mm
I have noticed more differences in tire brands than with tire widths. Also, I have noticed more differences with tire pressure than tire widths. Firm side walls is a good example of the former and inflation below the recommended minimum is a good example of the latter. These two characteristics taken together provide an excellent experiment, especially if two different brands are on the bike at the same time. Their behavior is more easily seen.
My experience so far is that 25c Continental 5000 TL's corner best in all conditions when inflated at recommended pressure (including adjustments for total weight) and 23c Vittoria corsa Speed TL's are the fastest and most comfortable when the road has almost no turns (using the same inflation metrics). I do not ride in foul weather conditions, I live in Arizona. I do; however, ride in all types of road conditions. One other thing I've noticed is the larger tires seem to bounce more than smaller tires; a condition that is unpleasant.
wider tires bump more if you use the same pressure.
I cannot say I agree with all of your conclusions but you opened up a really good discussion!
Completely agree Alex; i train on 28mm which are great for a wide range of road conditions when run at a lower psi, and race on 23mm when the road surface is fairly smooth. 28s are faster and safer on irregular surfaces, 23s are faster on good asphalt. Think Roubaix vs track. Pressure is the sensitive variable.
I was left confused. None of this seemed to apply to my reality. My tri-bike as 22s (which I measured to be 22.17mm) and I inflate them to 90psi. My road bike has 28s on them and I inflate them to 55psi. From your video, I think you are saying that my road bike tires will be slower because the speed breakeven for them with the 22s is more like 78psi?
Enjoyed the video. I used the tyre pressure calculator. I haven't seen a tyre pressure calculator that takes into account the shift of weight to the front wheel when descending fast with the inevitable braking. I tend to work on a 10% difference front to rear to avoid squirmy compression on fast descents. What do you think?
You are 100% correct....if you are descending fast we would advise the same tyre back and front despite the balance being 40 to 48% front on flat
I'm 170 lb, and I have recently been alternating frequently between my 25mm tired Roubaix and 32mm tired Domane as I have one bike at home and one at another city I that that I frequent for work. I run the 25mm tires at 100 psi and the 32mm tires at 75 psi. I have been averaging about 1 to 1.5 kph faster on the 25mm tires for a similar effort. Not scientific, I know, but I have come to realize that the 25mm will be my choice for speed, and the 32mm will be my choice for gravel or rough or slippery roads. Comfort is about equal on both at these pressures.
Those are the same tyres, but one is wider? And further, this was not about aerodynamics, where 25mm might have an advantage. That was not addressed here.
Thank you!!! I've been say for a long time that tires serve 2 purposes. 1) road surface and rider weight. But cyclist are going for the soup of the day!!!!!!!!!!!!!
There are two things to consider, all other factors assumed constant.
1. Rolling resistance
2. Moment of inertia of the tire
Wider tire at same pressure will have lower rolling resistance, but higher moment of inertia.
Wider tire at a lower pressure to match same rolling resistance with a narrower tire will have better road shock absorption.
Higher moment of inertia with wider tire is the only big drawback, so one cannot keep going wider. Moment of inertia kicks in adversely during acceleration and when climbing uphill.
Therefore, a good compromise between tire width tire pressure and weight is essential in a race. The course gradient and road conditions must be considered carefully
Moment of inertia sounds impressive, it makes it seem as though you know what you're talking about. Well done. ;)
Meanwhile, moment of inertia is irrelevant to a rolling wheel, all that matters is weight. The difference in weight between wider and narrower tires is generally of little consequence compared to overall wheel weight and certainly compared to bike+rider weight.
A wider tire is not worse than a narrower one because of weight (or moment of inertia) unless you are racing up the steepest mountains and even then it would be hard to measure. Completely irrelevant to 99.999% of cyclists.
Great! Perfect explanation! I always been convinced of that toughts.
Love it, great! It's nice to see some actual science. It would be super cool to see a watt-meter comparison to prove this. Test the hypothesis, right? more like scientific fact, but anyhow
One advantage I see in bigger tires with lower pressure is it is less likely to puncture with a sharp object. At half the pressure there will be half the force for it to penetrate. That's why my training/commuting bike has 60mm G-one tires! I ride mostly 25psi. And I can say thats a decently fast bike that can keep up with the peloton on group rides, no problem.
And I also think for road a 25mm tire is a happy medium since the roads here have cracked asphalt and debris. My race bike has gp5k 25mm that measure nearly 29mm on my 23 internal rims (30.5 external) I can train with as low as 50psi on them, but usually 60, and pump up for races on better pavement. I'd ride 23 if I had narrower rims. Before this I rode Attack 22mm on older Zipps and they were great. But to get decent comfort I sometimes pinched... Now it is solved, with my current combo its both fast for racing and if needed I can ride over cobbles with less pressure without bottoning out.
So I guess the point is use narrow tires if your roads allow to do so without flats. On a TT bike it would be just fine to ride Attacks or Supersonics.
But for the vast majority of riders and uses 25 or 28 will do it fine, and you won't loose much on the race day. Gives a good range of pressure choice. If you need 32 or bigger just get a gravel bike...
But also a smaller tyre with less contact has less likelyhood of hitting a sharp object on the road
@@ojanssensande Fair point. But in practice wider is working much better for me. Usually I can see and avoid debris with both, and I don't feel I've been going over more stuff that I didn't see. Well, maybe I am - and not getting flats - so it's working! :)
@@ericoschmitt
Lucky you :)
Punctures are so annoying. I would like to run 28 or 32mm on my bike, too! Doesnt fit sadly...
32mm at a low pressure must be really comfy + safer in the winter
@@ojanssensande thats another reason both my bikes are custom steel and I designed the CAD myself!
I havent tried bigger but my road bike should take tires measuring at least 32mm or even a bit more. Perhaps the conti 32 gp5k would measure as big as 36 on my wheels, then maybe I have trouble.
@@ericoschmitt very interesting indeed! I like that you custom build your own bikes.
The reason I didnt buy another bike yet (apart from money) is that there is always something wrong with shelf road bikes for me. Even though these days, you have got plenty more options.
Thanks for doing this if only to get front row seats at a wildly entertaining comments section!
As a rider, I just match the width of the tire with the bike . For instance, my 1987 bianchi, I put 25mm smooth tires instead of 28mm because it's more comfortable to ride even if the road is rough (less resistance while pedaling). If I'm riding on wider tires, say a 38mm on a single speed, I would ride them over bumps, rain, or gravel. Riding wider tires would create more resistance and make it more of a challenge. I would not say that wider tires go faster, but will make it a smoother ride at a slower pace. Also what about tread? Smooth tires would obvious go quicker on smooth roads and treaded tires have more grip on rugged terrain going a little faster would it not? Enlighten me if I'm somewhat right or wrong.
Brilliant information, thanks
Love this! This is the message I’ve tried to convey on my Triathlon channel. If fatter was better we’d all be racing on Fat bikes. And I’ve literally read people say wider is faster. It’s just not that simple. Also, we should mention the width of the rim / tire combo will make a large difference in aerodynamics. And eventually aerodynamics will trump rolling resistance as we speed up. I think people should potentially start with road conditions, then pick tire pressure, then pick tire width that’ll accommodate the desired tire pressure.
Thanks so much for this video. 👌
Exactly. By some of the strange theories I see advanced on the net there could never be a tire that is too wide for performance purposes vs. a skinny tire.
9:18 Yeah, I ride wide tires because the roads out where I live are just terrible. Cracks and bumps everywhere!
It would be good to hear more about tyre width versus aero gains. I guess smooth transfer of airflow is more important.
CRR vs aero is here: fft.tips/tyre; also check out this comparison of 23mm, 25mm, 28mmm, 32mm tyres GP5000: www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison
Check out Hambini's test data and conclusions. Spoiler: tire-and-aero coupling is always best, which means 23c tires are usually the best with modern aero carbon wheels
@@rominhoferrari do you mean the big wheel test? No one seems to know if Hambini data are real
@@rominhoferrari What about wide tires on equally wide rims, like 25mm external? Maximum aero coupling benefits, but still potential for better rolling resistance on rough roads?
@@joshtipton7417 this might seem weird but a 25mm external rim is typically only 17.5c internal bead width and normally a 23mm tyre will actually match up externally to 25mm (caliper)...however I take your point, match rim to the tyre for maximum gains.
Intersting video, but the entire advantage of going to 25 or 28 is that you don't have to go "like for like". If I ran 23mm at a like for like pressure to what I run in my 28's or even my 25's, I'd get pinch flats every ride. The entire advantage of larger tires is that you can run them softer without risking your tubes, which results in a straighter hub path with less vertical energy applied by the tire to the wheel rolling over imperfect surfaces. The ideal rolling resistance will always come from the narrowest tire at the highest pressure that will still absorb the greatest amount of imperfection in the road surface you are currently riding. For most riders on actual roads, that is going to be either a 25 or a 28. After that, the extra weight of the tire and tube and the larger contact patch start to overwhelm advantages in rolling absorption unless you are spending time on gravel or dirt or lots of really bad pavement.
I’m just speaking for myself I’ve tested 23,25,28 on the same bike same roads same conditions and every test I’ve done the 23mm always road faster then the wider tires and where I live in Canada the are horrible but the 23’s rode fast no matter what test I’ve done so I do agree with what you had to say my thoughts only thank you
did you take in consider position of moon because of gravitational waves
I'm also living in Canada but the road quality is not really good. I got a bike with 23. Will it be fine? Strong enough?
Simple solution is to have a couple of wheel sets for different conditions. Narrow for premium asphalt and wide for bumpy roads etc. At a certain point comfort may be more important than speed. Real enthusiasts will match the right tire for the route. I stick with 25mm personally. 28mm I think would be ideal on longer rides with long rough stretches, but not my go to. Off road is whole other animal on this topic.
At the same pressure and load, a wider tyre's sidewall and overall casing flex will be spread over a larger area. With a more gentle casing flex comes a reduction in energy absorbed by the tyre. It's comparable to bending a 4 inch strip of sheetmetal back and forth, and a 2 inch one- the 2 inch one will get twice as warm. Energy spent. I read from greenspeed that smaller diameter wheels combined with wider tyres have better rolling resistance than larger narrow wheels. There's much more at play for having smaller wheels on a trike though such as side loading and turning circle. That aside, the smaller diameter is said to be faster given the road is good.
Best video out there, nobody is riding different widths at the same pressures but all testing is done with same pressure giving false results.
contact patch area may be the same , but a wider contact patch has a smaller circumference : it's the deformartion along the circumference that constitutes rolling resistance (actually the closed line integral along the circumference ) Obviously , a shorter circumference will reduce RR
My experience... the narrow tyre (say a 23mm) requires a much higher pressure- to avoid pinch punctures- than say a 25 or 28mm.
Thus to avoid pinch punctures the ride on my bike with the narrow tyre is extremely hard....
Even with a slightly less pressure required than a 23mm, my 25's are so much more forgiving- and stable.
The larger tyre also has stronger walls- again helping its stability and less likely to "fatten" under equal weight- even with less pressure.
In addition, with regards rolling resistance, the "hard" 23mm rides so hard, the shock and vibration is awful, causing the bike to vibrate badly- which actually slows me down quite a bit... indeed on some road sections where I live, I'd be faster on my mountain bike...!!
All things considered- leaving the science behind, my 25's are SO much faster than my 23's- and sweeter- to a point I may try 28's...!!
"leaving the science behind, my 25's are SO much faster than my 23's" Would you care to give some data and explain methodology of tests?
@@JanKowalski-pe9lo Not "tests"... simply my riding times are faster on my 25's- AND they feel so much better on the road- FAR less harsh a ride on less than ideal road surface sections- also making for a slicker ride...
I've been riding long enough (nearly 49 now) to know when a bike feels and IS faster....
@@zaneclone Well your statement is pretty bold as you`ve said that they are faster not that you feel they are or that you are faster on them. If you are experienced in cycling or/and in science you should know the difference.
thanks
Very nicely presented and explained (as always). I've run through the same calculations and have drawn the same conclusions previously. Keep up the good work 😎
I agree on all except one part. Slipper conditions higher ground pressure is best. Ie Honda Civics small tires higher ground pressure great in snow.
💯 % agree escept regarding resistant coefficient: it’s ok in a lab between different materials (pure materials). But in real life, rubber could be considered as an homogeneous material, but asphalt not @ all (a drop of oil, a stone in the material, ...) In this case, wider contact patch grips better due to the more amount of asphalt to achieve an “average asphalt resistance coefficient” and to avoid a sudden change of grip.
As always, a good issue and video.
Thanks
Thank you for this valuable insight into grip. Is there any way to work out average "asphalt resistance coefficient"
@@Fastfitnesstips Just thinking aloud...
Similar to CPAAURA...
Road surface composition varies--different amounts of different materials used in different asphalt road mixtures...
But it's probably even more complicated in that 2. real world riding conditions include debris (as you mentioned, wet, sand, oil, etc.)... so... a surface with a lot of road debris (sand covering 100% of road surface) = no improvement with greater contact patch since the coefficient of friction is going to be the same (uniform sandy surface)... but on a surface with spotty road debris, it's a statistical game... where the contact patch touches asphalt rather than sand, it will grip as well as on clean asphalt--the wider contact patch means greater chance of contacting clean asphalt, a little like shooting birdshot vs. buckshot vs. slug.
The amount of air pump into the tyre eventually creates more weight. Should i say that more weight apply end of contact area would be lesser rolling resistant?
I thought tests done to measure the watts needed to rotate the tyres varies with tyre pressure and width but does not account for aerodynamics, Each size has a sweet spot at which the tyre compound makes the results the same so compound also comes into play, money no object you could change your tyres according to the weather and road conditions, any one set of tyres is going to be a compromise. I chose 700x28. But am now using 70x32 continental 5000. Just for the robustness over potholes at lower pressures they might be 2 watts slower but I nearly notice the difference.
Hmm am a MTBiker just moving to rigid fork touring bikes and 65 PSI rear 700 x 32s feels great! some (mostly roadies) tell me its on the low side but i guess i am used to "squish" but more importantly and not getting pinch flats so i guess i'm good ^^