We know wider tires have a lower rolling resistance for a given pressure. We know lower tire pressures are faster on rough surfaces (anything other than super smooth surfaces). But is there a downside to running wider tires on road bikes? Si & Alex have been investigating!
Welcome to GCN 0:00
What are we trying to find out? 0:43
The bike tires we’re testing 1:19
The correct tire pressure for cycling 2:15
Delivering a fair test 2:24
Cycling on 35mm tires 3:40
Do 35mm tires fit on a road bike? 5:12
Our experience with wider tires 7:26
Which tires are the best? 10:20
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26 versus 30 versus 35 we know that wider tires have a lower rolling resistance for a given pressure and we know that lower tire pressures are faster on rough surfaces but is there actually a downside to running wider tires on road Bikes In theory that tire should be slower than that the biggest lie I’ve ever had in my entire life I kind of don’t know how to break this to you all but basically effectively what we’re looking for today is to find out where the wider tires so trendy so hot right now and
Supposedly so fast actually hold you back when the road surface is good now before we go any further a quick request from us please can you subscribe to gcn if you don’t already your support means a great deal also let us know in the comments section which width of Tire
You think is going to be fastest and lastly hit the like button if you enjoy a bit of gcn does science to test it we’ve got three pairs of plli P0 race tires fitted to three pairs of elite Wheels Drive 50s the only difference between them is that one pair of tires
Are 26 mil one pair is 30 mil and one pair is 35 mil wide our test is on a dedicated cycling track and the surface of it is really really good now many people and I’m going to include myself in this category will think that the
Narrower tire is going to be faster on this smooth surface because it’s more aerodynamic on these wheels and because this smooth surface simply doesn’t play to the strengths of The Wider tires that’s right wider tires at lower pressures are faster on rougher bumpier surfaces so common sense suggests that
There’s going to be less or perhaps even no advantage to be had when riding on the smooth stuff was that tumble weed blowing across we’re setting up the wheels with what would be considered the optimal tire pressure for each and that’s according to the silker online tire pressure calculator now I can hear
Some of you already saying well it’s not a fair test if you don’t put the same pressure is in yeah but no for sure a wider Tire will have a lower rolling resistance for a given pressure but in the real world you don’t run wider tires
At the same pressure as narrow tires you run wider Tires Lower in order to get the same level of comfort and vibration absorption as you would expect and in fact the whole point is that you can run wider ties even lower to get more comfort and more vibration absorption so
That’s what we’re going to do we’re going to log some laps after at 100 wats some at 200 wats and some at 300 wats and see if the speeds vary between different tires we’ll keep our body position on the bike constant our clothing constant and we’re going to try
And get the test done quickly so that the weather hopefully also remains constant but we’ll finish the test by repeating the first one again to act as like a primitive control but we will of course be monitoring weather conditions throughout the day using the gcn weather station Alex how’s it looking out there
Bud windy but okay 35 mm tires I don’t know let’s go 3 two 1 go you got to go a bit quicker mate I’m going slow in the name of science Speedy 20 six is coming up they actually measure 28 we’ve just found out using a set of calipers right beep beep beep
[Applause] beep tell you what riding at 100 wats is nice 200 WS okay and then 300 WS like my my thoughts of them riding around the circuit I think just feels normal yeah you know what I mean like I don’t know what I was to say about them well you’re
Right feel normal that it makes your robot feel normal yeah and like that is almost like the Baseline cuz they measure up as 28 don’t they okay modern modern wheels are wider 26 more tires tend to be a bit wider yeah and I have not put that amount of pressure in any
Of my tires for years no but because the surface is so smooth you just don’t notice it like it’s just it’s fine it’s yeah it feels not right I think the second if you took 26’s to crappy roads country lanes with those pressures yeah you’d be shaking your teeth
Out you just have a moment to admire a pinell Dogma with monster truck tires on look at that it fits all right up front possibly a a little snug at the back maybe and maybe a quite snug there as well but it looks so rude well uh count myself back in yeah
Three got speed Alex two one yep oh missed my pedal great oh God sake hundreds hundred easy tiger don’t go too fast yeah all right it’s time for the pinell monster truck I mean genuinely I’m excited at the prospect of this such a nerd right Ready 35s feel very different to ride yeah they particularly going from the 26 straight to 35 they change the handling of the bike they because that is it pneumatic Trail I think it’s called I mean it sounds sounds great yeah I think it is cuz like the the tire is so much
Like wider the contact patch is a different shape so actually the steering of your bike is therefore different and I did I tell you what else I noticed that in this little section of crosswind I was noticing it felt slightly less stable with the 35s I’m assuming because
The rims are not designed to be aerodynamic with 35 mil tires is like catching in the yeah so if you got like a narrower rim and you put a big tire on you get this sort of balloon shape effect which means not only if you got a
Taller Tire the wind’s hitting it more from the side as the wind comes off of the rim it’s then coming out round over the tire so that’s the reason why so in theory why the rim would fix that in theory that tire should be slower then in theory and that’s what we’re trying
To find out right that’s what we’re trying to find Out two one look at this that is absolutely disgusting you see that that cassette filthy this is what Alex has turned up with today he’s about to put this on his bike I just can’t understand how he’d let us down like that that the biggest
Lie I’ve ever had in my entire life I don’t want to put that M cassette on my bike that belongs as s well I mean technically it is mine yeah oh Jesus all that contamination on my chain [Laughter] already I I’m embarrassed to admit how much it’s upset of me well no time like the present 3 2 1 go go they look about right these they measure up as 31 just in case you’re wondering uh right [Applause] 30s kind kind of felt the same as a 26 yeah I just I wouldn’t ever run a 30 on my road bike just because it doesn’t feel like a road bike tire we see I do I fairly regular use a 30 I I was using 28
Mil tires like back in 2017 and people thought it was out there it was wild he got 28s on no wonder day you won the Sprints Jersey at the tour of Britain isn’t it you had a massive Advantage yeah people in general are slow to go a
Big change across anything in life let alone cycling so I think you do get like incremental jumps with Tire width you tell people that wide tires are fast they get all I’ll try the next little bit up whereas in reality you just go one big jump and you’d be like well cool
I’ve got all the advantage rather than eeking it out over a period of like 5 to 10 years yeah yeah well I mean like it’s taken a long time it’s also taken a time for tire manufacturers to catch up right because previously bigger tires were all like slow you know puncture resistant
Whatevers like whereas these plli 35s now like they are the same as the 26s they’re super fast super Supple like you know we haven’t had that option before yeah I hav thought of it like that because yeah typically go wide manufacturers assumed that you wanted like a heavy robust puncture resistant
Tire for Trucking across like gravel nonstop whereas if you want the speed and comfort Advantage get the top spec hold the like sing and danceing tire a just fat version Yeah right then it’s the moment you have all patiently been waiting for it is results time I kind of don’t know how to break this to you all but basically they were all exactly the same pretty much there was like such a little difference between everything we’re going to count
Them as the same yeah so like in terms of margin of error they were all exactly the same potentially the 35 was fractionally quicker fractionally So within within the you know Realms of uh of statistical error but that has completely blown me away because I did not think it would be
As fast as the other tires I thought the fat boy was going to be slower oh yeah I I did come into this the fat boy was going to be slower that’s thrown me well sorry I don’t you know the tire the fat boy Tire um I came into today trying to
Have an open mind on this but I I did have this sort of preconception that the 26 was going to be fastest on the smooth surface and I’m kind of glad to be proved wrong because I am an advocate wi tires I know the bike industry is trying
To sort of push it and say this is great because Perhaps it is just good yeah well yeah so so on on the surface that is least suited to a wider tire and by the time we’re doing 300 wats my average speed your average speed was about 38k
An hour I mean we could actually just put a nice little chart together and whack it up on screen for everyone to look at this themselves yeah but so 38k an hour like we’re not hanging around at that speed so even at fast speed the 35 was not slower my results my personal
Results varied most at the lower power which is kind of interesting I thought yeah so anyway let us know what you think because has that surprised you do you run wi tires will you consider running wi tires now I mean I still wouldn’t put a 35 on my
Binella if I’m totally honest even after all of that there’s something still feels a little bit wrong at the minute maybe just exeptions we don’t want to take big leaps of faith I still stick by what I said in a gcn tech video a few weeks back 99% of people could benefit
From just having the widest Tire possible that fits into their bike and running it at low of pressure and I think we’ve kind of cemented that in even if you’re riding on smoo surfaces most of the time there you go get involved in the comments section down
Below and remember give the video a like if you’ve enjoyed a little bit of gcn does science okay bye
46 Comments
🤔 What width tyres do you use? Have you gone wider and noticed any difference?
Let us know 👇
When I talked to riders 30 years ago, no one believe this stuff. I’ve got a lot of outraged answers therefor. Other stuff must wait another 30 years. Dumb industry. Dumb bikers
I'll see you jokers in 2026 on my slick 55s! with the biggest hooks you've ever seen !!!
Shills.
I would like to see the same test but with fast rolling gravel tires compared to the road. How much speed are we actually loosing so we can ride off road?
Well BicycleRollingResistance did this test like 5 years ago, and this is exactly what they found out. At the same pressure, the wider tyre is faster. But at the same comfort level (or as they measured it – the deformation/tyre drop under the same weight) the results were pretty much identical in rolling resistance.
A 25lb bike is faster than a 15lb bike.
Amazed how consistent your results were for all the variables you would have in that kind of test …spent 30 years in the tire industry,… to measure what you were trying to demonstrate we would have done in a controlled indoor environment on a test drum with various grits to determine friction coefficient. As a recreational and Club cyclists for many years I have transition from 26 to 30 on the road bike with no loss of speed but more comfort!
I'm sticking with my 4 inch fat tires. Very comfy and the sound alone will give you a couple of hundred watts of boost.
Why not test this on a rough road, given that is one of the most talked benefits of going to wider tires?
Surely wider (=heavier) is worse for change in speed (acceleration) and direction?
So what pressures did you put in each tyre?
The biggest I can run on my Trek Silque are 28s!
Yes but none of this works if you have wheels from 2006.
I ride 32c with 5 Bar in it, and its feel great
I run 28’s across most of the bikes I own which is the max they can take, I feel the difference versus the newest disc brake road bike I bought that has 32’s. That said I need to get some proper tires for the latter as it has commuting style tires on.
Don't everyone forget who pays for the content, Drive wheels ,Pirelli tires the bigger the tire the more it cost the more profit they make. Sell new wheels to fit those bigger tires.
What size tire do velodrome riders use what width. Because it is faster.
In regards to slower speeds like climbing, I wonder if the benefits are really only comfort
Hi! Thanks so much for all your amazing videos!! Been watching for years and you guys are awesome!
About to do a Cortina D’Ampezzo to Nice bike trip with my wife (29000m of elevation gain) and we’re reaaaally wondering if wider is still better on climbs…Any advice?
Should we be surprised at this? I'm a recovering physicist and a commuter cyclist. At 38 kph or roughly 10.5 m/s, a rider typically produces a drag force of around 30 N and this takes about 316 W to counteract. The rolling resistance is about 1/3 N requiring a power of 3 W…
30mm tires on my ritchey logic and 32mm – 35mm on my titanium all road. They just feel nicer on century rides.
I used to work for Pirelli Tire, and the answer to your question is "No," wider tires are not faster, with two exceptions. Understand that a wider tire is heavier, it has a larger contact patch, and is less aerodynamic. Given the same materials, pressure, and diameter, in a straight line it is physically impossible for a wider tire to be faster. The two exceptions are when cornering and braking, a wider tire will corner faster and brake more quickly than a narrower tire. When you are testing narrow vs wide tires, you need to understand that as tires get wider, their circumference changes, which affects your final drive ratio. If the three tires you tested had the same circumference, and you ran them all at the same pressure, or you adjusted your gearing to compensate for changes in tire circumference, the widest tire would be the slowest tire, unless you were on a course which required frequent turns and braking. I myself ride wider tires, not because they are faster, but because I prefer the balance of comfort and handling wide tires provide.
Nice test💪 Would be great to see same on rough tarmac 😅
In the late '00s one of our more successful teammates always rode wide tyres. I wish I had followed suit instead of beating myself up on 23s inflated to the max. Now it's 28s and 61-64 psi on my TCR.
Interesting about Tyres sizes. I am doing the Tour of Bristol bike ride 65k.
I did renon the other day the roads are not good.
Which of my two bikes should I do it on my road bike with 26mm tyres of my Mountain bike with 40mm tyres on.?
Comfort for me. for the hack bike, race bike 26mm.
Intro was like adult movie techno music.. GCN editors what have you been up to?
That Orox R14 you sold me on runs 2.6"/66.04mm tyres, so I guess I will be using wider tyres.
With bigger tires you have smaller gaps between tire and the frame. It could actually lower aero resistance.
GREAT video, thanks guys! I have a 10 year old road bike which I plan to upgrade (to a new bike) this year. I love the idea of putting 35 mm tires on so I can do light gravel, and now I can tell my blowhard friends (with whom I fit in quite well) that I will be no slower than before.
Done with racing, now I’m all for comfort. 32mm and I’m never going back. Still can keep up with my friends who run lower than 28s and more comfortable.
Now we need a comparison on cornering feel. As the guys said, the bike felt funny and cornered oddly with the 35's.
Just stick to Newton's laws of motion
Wider tires at same pressure gives lower rolling resistance, but for same brand/model tire, wider is heavier hence higher moment of inertia.
At constant speed, wider is likely better because of lower rolling resistance, but tire with lower moment of inertia is better if you have to keep braking and accelerating during a race such as in a criterium
It's alright dropping the pressures if you ride tubeless.
I run 34c. Mostly for comfort but also because I have hookless rims. They were on my gravel bike as the road wheelset but now I have them on a Specialized Roubaix SL8. When they wear out I'll switch to the stock 32c tyres that came with the Roubaix.
Wider tyres do have a lower rolling resistance for a given pressure but that means they’re harder.
When pressure is corrected to have the same deflection for a given load, the rolling resistance is nominally the same.
Norcal did this video first ❤
35s is the sweet spot on rolling resistance websites. They're the best all round.
I haven't noticed any comfort or speed differences between 25mm and 28mm.
I have 37mms on my gravel bike and that certainly feels different. But the entire bike is different from my road bikes. Geometry etc.
I guess I could put some 28mm on it and see what that'll do. But I don't know if the rims could fit a 28mm and I'm also extremely lazy.
How do you know what is the widest possible tyre your bike will take – how much clearance do you need around the tyre to the frame?
28mm is the max that my road bike accepts so I will ride 28mm 😄
I have been using 30's and recently moved to 32's. More than just the speed, if one is riding for few hours, the overall comfort you get from a larger tire over the longer period is just nice.
2:04 Hm. Is nature giving me an idea of new type of wheel? Tumble weed. Tumble wheel. Even less rolling resistance. On sand. On tarmac. Everywhere!
lol you straight up stole/leech this content from nocal, amazing how low GCN are willing to go
Before I started racing in the early 90s, I used to run 27" x 1 ¼" (or 1 1/8": 630-33/35) on my road/touring bike. Many happy miles. I discovered that Panaracer made a nice, supple lightweight one (which wasn't $$$) and used them almost all the time. Then I got a 'proper' road bike and 700 x 20mm was almost a must-have. There was plenty of frame clearance for 28 or even 30mm; but no 'serious' road tyres came in that width: you would have been laughed at by "the bunch" turning up to even a club ride on those. I felt like I was working a lot harder: but I was 'racing', so imagined that it was all part and parcel of something that seemed a tad sado-masochistic, at times. It turns out that I was working harder, to no extra effect: which goes to show that fashions (pushed by those with a financial agenda, usually) without research and data to back it up are horse-poo.
I think tread makes a difference also. Like compare extremes like a mountain bike tyre or a gravel tyre to road bike tyres. The weight and tread makes a difference. I have crossover bike and 2 sets of tyres one a gravel soft off-road set and a road set, the road set is faster and less fatiguing on tar than the off-road set are however comfort there is also a noticeable difference