Machka 

Don't most people ride with 25s or 28s now?

Leinster

I‘m still on 23s. I have 25mm Kenda Kwests on my commuter bike, but my road bikes (one steel, one Al) both have 23c GP4000s. I have no problem taking them on bumpy roads and even some hard-pack gravel.

The 23s got cheaper as everyone started buying the fatter tires, so it’s worked out great for me.


I did my formative riding in the 90s riding 20c Michelins throughout my teens, so my experience is probably different to others not of my age group.

surak

The Silca blog had some real-world and lab-tested takeaways about road-sized tire pressure optimization on cobbles and road/track surfaces. On cobbles, they observed that lower pressures are always faster, until pinch flatting.


On asphalt, higher pressures are faster until they're past some optimal point, after which rolling resistance is far worse per-PSI over-inflated than under-inflated.

So what's the best strategy when one rides a mix of bumpy and smoother surfaces (which is most of us living in the real world)?

BritishV8

2 cents

1) (Size) It's winter, so I'm riding tubed Conti "All Season" 32s. I wish I'd bought 28s instead. If I had newer/wider wheels the 32s would ride better. If I had more clearance at my (rim-brake) calipers, clogging up with wet pine needles wouldn't be such a nuisance. I do like that I can enjoy occasional detours onto gravel roads better than I could on narrow tires. When the weather gets nicer, I'll probably switch to 25s in a faster tire, but 28s are okay for all-around use.

2) (Tubes vs. Tubeless) I tried tubeless tires. It was an expensive and short-lived experiment. I now believe tubeless is a mistake unless you're running a lot bigger than 28, and also a mistake if you're riding somewhere with sharp road debris.

Russ Roth

I don't have tires of the same brand but I find 28s every time I use them are just slow and heavy feeling even running higher pressure. I prefer 25s set at 95psi, haven't found the ride to me rough and find theyre a nice level of comfort.

noodle soup

I started racing in the mid-80s, and and rode 20-23mm tires until a shop gave me some 25mm tires in 2015.

In late 2018 I tried a friends CX bike with 30mm Schwalbe Pro One tires, and that convinced me it was time to go wider. Now I use 30mm Schwalbe G-One Speed tires on 30mm wide hoops(23mm internal width). They blow up to be about 31.8mm wide, and the ride is smooth and fast. Unless I start TTing again, I'll never use narrow tires again.

RockiesDad

I'm not smart enough to figure this out but can anyone figure out what the volume is for each of these sizes? I assume you have to take a cross section of the tire inflated and also use the same wheel inner dimension. This way we can at least have a better idea "percentage" wise how much difference we can expect for each tire size.

Anyone?

RockiesDad

Okay I tried to do some quick math and it seems that volume of a 28mm tire is about 29% greater than a 25mm tire. A 32mm tire is about 33% greater than a 28mm tire. Going from a 25mm to a 32mm will be 53% more volume. Does this seem about right?

I think my next tire will be a 28mm. I'm using 25mm now and its not too bad on my roads and hard pack gravel with a carbon frame and fork. I should be gaining about a third more comfort from what I'm using now according to my calculation and my butt-o-meter....

HTupolev

The simple rough way to approximate it is to compare the squares of the tire widths. So, a 2" tire has around quadruple the volume of a 1" tire.

But I'm not sure that this is a useful way to look at the situation.

If you want to talk about how much suspension a tire can offer for paved riding, the most intuitive single number to use is probably its inflated height, roughly proportional to width. That's indicative of how far it can deflect before bottoming out, and it also gives the most direct sense for how much deformation the tire will experience when it's deflected by a certain amount.

I think "volume" gets used by fat-tire salespeople because it makes the differences sound bigger than using a tire's first-order dimensions. The volume of air that exists in the chamber has little direct relevance to anything. (Otherwise people would design deep tubeless rims to use extended air chambers beneath the bead seat area.)

popeye

And handle quicker and more responsively. I'm not going to put 28's on a light crit bike (at my weight).

WinterCommuter

i’ve tried 28s. I’d say that i prefer 28s to 25s (or 23s) on my road bikes (sworks venge and sworks tarmac). I run my 23s @ 100psi, 25s @ 90psi, and 28s @ 80psi. I really like the feel of cornering on 28s. As far as speed goes, on flat itt rides, i find 28s slightly faster than 25s. I notice the extra weight of 28s under heavy accelerations like sprinting and coming out of corners. I haven’t gone tubeless on any of my road wheels (fatties yes). I’ve only tried 1 version of 28s, conti gp4k2.

studbike1

At these widths, the type of tire is going to make a bigger difference. Going from a 23 to a 28 on a really stiff tire like a gator skin is only going to net you more durability. The ride and grip will still be eh.

​​​​​Also depends on your bike. I know we're all attached to our bikes here, but in my opinion, anything above 25/26 and I'd rather move to a 650 size wheel and a 32 or wider tire. My experience is that mounting 28s on my road bike did give me the extra grip and comfort that people mention, but it also robbed the bike of it's snappy, aggressive character, and the razor thin clearances in the frame were a source of anxiety. I also had narrow rims so this may play in to it, a wider rim will let the wider tire roll more naturally.

adamrice 

I've got 23s on my old racing bike, and 32s (with tubes) on my new commuter/winter bike. The chainstays on my racing bike are so short that I doubt I could fit 25s on it.

I recently rode a 100k out-and-back on my winter bike that I had previously done on my racing bike. My overall time was 4:30 slower, but there are a lot of confounding variables (both days were very windy, I wasn't hydrating enough on the second ride, different bike geometry, etc). On this route, there's ~30 km of riding over very rough chipseal on the stretch of road at the turnaround end. I was hoping that the 32s would take some of the sting out of that. I have to admit that I still felt pretty beat up on the 32s—but I was averaging 18.46 mph on the 32s vs 18.01 mph on the 23s for that stretch..

Nman

If your bike will only clear 28's, that's what you should ride. 32mm is better, lower pressure, more grip, more comfort, safer. Tubeless.

Commutess

I switched from 25's to 30's and I love them. I use 80psi and they are perfect. My application is a single speed so probably not comparable to what your application is.

seypat

The poll needs some other options. I'm 5'8"ish and around 200lbs depending on the time of day/day. I have a bunch of 52-56cm old steel bikes from sport tourers to crit bikes that I rotate through. They all have 80's or 80's style saddles on them like the Selle Turbo. I have Pasalas from 23-28 and 27 x 1 1/4" and various Conti GPs from 23-28 on similar wheelsets that go on and off of these bikes. I can switch them out and compare them side to side. I generally ride them with about 10lbs less pressure than what's recommended on the side. I go on rides with and without padded shorts.(no bibs/not shorts for me) My experience is that there is not that much difference through the size line. There's some, but not the epiphamy like discoveries people are describing. The 23s are a little firmer and lighter. The big tires are heavier and a little more lethargic. The bigger tires do give some more confidence when descending. That's about it, as far as comfort/feel goes. The type of shorts/bibs/saddle/bar tape/brand of tire and whether you wear gloves might make more of a difference than size. I didn't really notice much performance differences 23-28. Above that, there is some drop off. The difference is small enough that the cheapest price between the sizes within a brand line would determine future purchases. I generally get 25s when getting new tires. You want some difference in feel, put an a$$ hatchet type saddle on there. You'll feel the difference no matter what kind of tire you have.

noodle soup

No it doesn't

seypat

It doesn't have a "I liked 28s or blank size better than the 25s" option. Notice how many responders are talking about sizes other than 28s.

dimini

I promise that I'm not a Troll... Guess I must be one of the minority hardcore C&V guys because when it comes to road bikes, I'm totally content riding on vintage tubular rims with what I think are 23's. I don't ride centuries anymore... just a solo cyclist who does routine 15-20 mile rides. However, for my urban rides, I usually ride on 26x1.25 (32c) Avocets on various 26" hard tail mountain bikes, which feel pretty good in a heavy-duty sort of way. I obviously don't understand physics as I don't see how riding 25 or wider road tires is more efficient. Interesting thread!

noodle soup

Start your own poll then. The OP asked what he wanted to know about.

seypat

Feeling it today aren't you? Maybe I should start a poll asking whether our current discussion is even relevant to the topic? I'm sure if we continue, a mod will tell us otherwise. I have to go to work, anyway. It's a big forum. I'm sure you can find someone and something else to argue about to keep yourself amused. Keep trying.

Clipped_in

I have 25's that measure 28mm wide on my wheels and they are great! My frame wouldn't clear full-on 28's very well.

CarloM

It's so highly dependent on tire make, model, and how it plays with certain inner rim widths. On my Black Inc 30s (17.5mm internal width) I had 25s that measured 27 and I assumed when I mounted 28s they'd be too large for my frame which has a max supported limit of 28mm. The 25s which measured 27mm were Mavic Yksion UST Tubeless. I put on 28 Conti 5K TLs and to my surprise, they measured just a hair over 28mm. So you just never know until you mount them.

63rickert

I measured. Just always have. They were 29mm. Also remember when road races would have gravel because rural roads were like that, so lots of racers used them. Correct no one talked about it.

Kapusta

I would not even consider 28s anymore.

Too small.