davester

My understanding of the tire research findings that have been published over about the past decade is that wider tires at lower pressures have lower rolling resistance and are faster on roads that aren't as smooth as a baby's butt (i.e. most roads we ride on) up to about 20 mph. Above 20 mph, air resistance becomes a bigger factor than rolling resistance so skinnier tires that don't bulge too far beyond the width of the rim start to get an edge. This is why the pros have been going to wider and wider tires over the last few years. What' I've read is that 25mm has become pretty standard for racing on smooth roads and that 28mm or sometimes even wider are used for rougher roads, thus providing a balance between rolling resistance and air resistance, depending on the characteristics of the course. For myself, since I seldom exceed 20 mph except on long downhills, I generally try to jam the widest tires that will fit on my bikes (typically 28 or 32 mm). Other benefits include making for a smoother ride (though note that some folks erroneously interpret the lack of a jiggly ride as being slower) and better roadholding grip when cornering on sketchy surfaces.

Barrettscv 

A complete summary

Wildwood

The speed at which air resistance is greater than rolling resistance is far, far, far below 20mph on a road bike with tires pumped hard on a paved surface.

If riding 48+mm tires at 30psi your rolling resistance may never exceeded the air resistance (riding on a paved surface)!

Wildwood

I believe the 20mph number has been used to justify an 'aero' road bike over a traditional 'racing' road bike - where the frame modifications favor air flow over frame weight reduction, etc

Climb14er

I have run 23’s on my Waterford RS33 since 2007. Have another pair of 5000S tires in reserve. They perform very nicely.

I-Like-To-Bike

The difference being that TV and telephones sold equipped with CRTs and rotary dials did dominate the market for many years, with probably 99+% of the total market. Bicycles sold to the public equipped with narrow ( less than 28mm width) racing tires was never more than a niche market of "enthusiasts."

70sSanO

Over the decades I’ve gone from 20mm to 25mm (that measure 26mm). I have one road bike with 28mm. I’ve also ridden 32’s.

For a fast rolling bike over a good surface, I think 28mm might be the sweet spot for me. I’d run the size if it fit.

From what I’ve read even professional riders have gone wider than in the past. I’m not sure if they will hit 30mm, but I think they are already at 25mm.

John

Carbonfiberboy 

We have smooth roads around here. Very little chip seal. I still ride 23s on 23 outside rims. Works fine. I out-coast everyone and have a BMI ~24, comfortable on 400k rides. Why would I change? I'm riding Conti 5000 latex tubed.

BlazingPedals

I've been on 23s for so long that anything bigger is 'fat' to me. With the advent of disc brakes on road bikes, it's now more common to find 25s and even 28s on them, but at least for road applications, I don't see tires getting any fatter than that. Once you get to 32, you're looking at gravel-capable, and while that may be the whole point, there's a whole swath of cyclists who just don't do gravel - or if they do they have a dedicated bike for that and it's got knobbies.

A lot of fellow club members have tried fatter tires, 35-40mm, and while they say they're *almost* as fast as skinny tires, there's that "almost" qualifier. They can be softer-riding, though.

embankmentlb

25 seems the optimal size for me. I have tried wider but generally do not like the mushiness of the ride, particularly if out of the saddle.
Another factor almost never mentioned is that the wider the tire the more mass. Not your best friend when climbing. I realize that modern technology has reduced wheel and tire weight considerably. It also adds to the complexity.
I am somewhat of a Luddite when it comes to such things. Rim brakes, aluminum 32 spoke handmade wheels, cup and cone bearings are for me. Simple things I can repair and ride! I guess that leaves me in the minority and a bit out of touch. At my age, it’s just fine.

John E

My 1980 Peugeot PKN-10 and 1981 Bianchi were pretty comparable in weight and performance, but the Peugeot easily handled 32mm (700Cx35 callout size) tires, whereas the Bianchi limits me to 700Cx28 Continentals, which are more like 26s.

davester

The total air resistance of the bike+rider is beside the point. What's actually relevant to the question of what width tire is faster at a given speed is the difference in rolling resistance for different tire widths (which is significant) versus the difference in air resistance for those same tire widths (which is exceedingly small at low speeds).

himespau 

The 1996 Merckx Ti I'm building up will fit 28's comfortably and probably 30's, but 32 appears to cut the clearance down too much, so I'll put 28c tires on it when it's ready to go (or more likely 25c tires until I wear those out as those are already on the wheelset I have built up and ready to go). In reality though, I do almost all my riding on Zwift these days so I don't really have tires on my bike when I do most of my riding. Being able to ride when the rest of the family is asleep, when the weather is garbage outside, and not having to worry about making the call of shame or getting hit by a car again outweigh the fresh air and nature that riding outside brings for me.

woodway

I love running 32's on my "do everything" Ti Cross Bike. Since I'll never ride in the TdF, I don't really need to worry about aerodynamics. The 32's handle the wide variety of road surfaces I ride on, and I won't hesitate to jump on mellow gravel with them. They also ride very comfortably compared to the 25's I used to ride.

Fredo76

Skinny tires are dead!

Long live skinny tires!

and 13-blocks!...



Long live Spot!

peterws

I'd maintain that rolling resistance doesn't vary with tyre size, but only with tyre pressure. The footprint will be slightly different, but the same area engages the road.
I keep my 32s rock-hard (don't have a gauge) and I find them just as quick, but infinitely more comfortable over any surface. Original tyres were 25; I binned them.

andrewclaus

Finally someone mentions mass! I agree, and I do a lot of climbing.

Of course that comes with fast descents. I've recently switched from 25 and 28 on a trial basis, and don't mind the extra rubber on the road then.

79pmooney

Yeah, the dominance of narrow tired bikes is over but I just picked up, a 1980s race bike that handles only <25c unless I file the rear brake (super short Cyclone with the pads pushed all the way up). Not a whole lotta bridge clearance either and 25s are the max to jam in the horizontal dropouts inflated. I tried 25c tubbies and no go. Soon it will get 23c tubbies; not far from what I trained on 45 years ago.

So bike's a loser. Uncomfortable, unsafe, slow ... (Well that slow bit hasn't been playing out nicely in my ride times These "slower" rides seem to be happening in less time. Haven't figured that one out yet.) Trouble is, my legs just don't get it. I climb on and just feel the sweetest, most efficient ride I have ever dropped this body on. I consistently ride harder and faster. Yes, I hurt more when I get home, but I also had more fun. (And am getting into better shape.)

And soon I will be going to the next step in the wrong direction. Inferior rims. Rims with no inertia to smooth out my pedaling. Rims that weigh 340g each. Are so skinny they are not remotely aero. Even closer to what I rode 45 years ago. (Sub 300g tubbies glued to 340g rims! Fun, fun, fun! Don't care if all the calculators in the world say that's slow. And racing - when that wheel goes by that you have to get on because that's the move you have to be in, wow! do light, light rims and tires make a huge difference! No I do not race and haven't for decades, but those wheels are still fun.)

dmanders

I wonder if this thread would draw different responses from the younger readers in the road cycling forum? Back in the day I rode skinny tubs. Now I ride 28 tubeless and love them.

cyclezen

I believe rider weight/mass has a lot to do with tire choice. Noticing in the few groups I currently might ride with, that larger riders, on newer bikes, will have wider tires. That makes sense. One can have a nice riding tire, without it being rock hard, with the wider tire.
For lighter riders there's less perceived difference. Sure they can ride at lower pressures, but may already be on lower pressures on their narrower rubber. I ride 23 & 25 (usually on the rear) at 72 frnt and 75 rear, and they're plenty firm for me. I rode a friend's bike which had 32s on it, and really didn't notice any real difference, he had his pumped to 75 & 80 - also seemed firm...
The young guys in those groups who are very strong riders ? 25mm almost exclusively... roadies... not grvl or touring ... err bikepacking... LOL!
Ride On
Yuri

bikemig 

I rode 23s and 25s for what seems like forever. Now I'm not interested in a bike that can't take at least a 28c tire. But then I'm nowhere near as fast as I used to be so a little fatter tire is helpful in terms of comfort.

Fredo76

Tight clearances on racing bikes were already becoming a fad in the late '70s. I say fad, because the disadvantages outweigh the non-existent advantages, really, except maybe for looking cool in the eyes of one's peer group. That fad marked the beginning of the fetishization of the sport, along with Cinelli hiding the handlebar clamp bolt...

Duo

my fuji touring bike wears 32s in the back and 35s in the front; also rock hard inflation, my pump gives me psi, so i do about 80 psi. my other bikes use 25s and i inflate to about 100psi.

i can tell the difference in tires easily; when i put the 35mm on the front of the bike, the vibrations were so soft compared to my trek racing bike. in the end, i like both bicycles, my trek is very light and tuned for performance. the fuji touring is the everyday exercise kind of bicycle.

for those with 25s, try experimenting with a 32mm on the front only if they will fit and see if that doesn't dampen road vibes to your arms. the 32mm tires may offer better tracking and steering when you need it. eventually i may try a 32mm front tire on my trek just to see the difference. if tire fit is an issue, you may be able to try a 28mm on the front, guessing that comfort would be a bit improved.

i don't ride long distance, so tire width and comfort are not high on my list.

scottfsmith

You are throwing away both watts and comfort with those high inflation pressures. Try 60psi on the 32s and 50psi on the 35s. Or at least something closer to that.

Duo

even at those higher inflation rates, the bicycle is noticeably more comfortable than my trek 1500 by miles. normally i let the tires go down to 50 or 60 and refill as i don't care to pump them up to often. watts don't concern me as that is one of the reason i ride is for exercise; at the higher inflation i get the best of both worlds: a long time before inflation and more comfort that my 25mm tires. if the bike was inflated to 50psi, then inflation chores would likely double.

thanks for the advice though, interesting.