23 vs 25 tyre

[marshalus]

Hi

Does 2 mm make really a difference? Does it make sense to put 25 on the standard 20mm rim?

[Marin]

yes yes

[fa63]

It does make a difference, as long as you remember to lower your tire pressures correspondingly. And you don't need wide rims to reap the benefits.

[AJS914]

Assuming they will fit your bike, you can try them. The 2mm difference is a small subtle difference.

I tried 25mm GP4000s (actually 28mm) on narrow Campagnolo Proton rims and decided that 23mm GP4000s (actually 25mm) were better for the narrow rims.

[Calnago]

Why did you decide 23's were "better for narrow rims"? I've got some Conti 25mm 4000SII's mounted on some older Neutron clinchers. I used them in Arizona and even some gravel and dirt crap (not ideal but worked). They were much better for that than 23's. I think it comes down to personal preference and the roads you're riding on. Or do you say that because they won't fit in your C59, which they won't, at least not with satisfactory clearance. The only hassle I found with mounting these tires on narrow rims is that when the brakes are adjusted properly, removing a wheel can be more difficult since releasing the caliper does not quite allow the calipers to open wide enough without having to "squeeze" the tire in and out. An annoyance for sure, but doable.

[AJS914]

Why did you decide 23's were "better for narrow rims"?

The 25mm GP4000s on my Proton rims seemed very bulbous. They felt a tiny bit more sloppy than the 23mm GP4000 and thus didn't handle quite as well. The extra comfort was a small difference. It wasn't like getting some magic carpet ride out of the extra 2mm so I concluded that I'd rather have the sharper handling of the 23 versus the extra comfort of the 25. Of course, on these GP4000s we are really talking about 25mm vs. 28mm because they measure wider.

It's not a huge dramatic change either way. If the OP wants a tiny bit more comfort then try the 25mm tires.

[fabriciom]

Sorry to steal you thread for a sec.

How about a 28mm tyre on a 25mm rim? (tubular)

[saeie1]

The difference between the two is fine, but I will choose 25 for safety reasons.

[Calnago]

Sorry to steal you thread for a sec.

How about a 28mm tyre on a 25mm rim? (tubular)

Totally fine. Especially if it's tubular. The radius of the rim bed designed for a 25mm tubular is a negligible difference for the radius of a 28mm tubular. Now, a 28mm tubular on a narrow (say older ~20mm wide Bora), would not fit quite so well. You'll get a decent glue bond on the edges where it's most important, but if that breaks loose then the bond in the middle may not be so great because of the two quite different radiuses trying to match up with each other. I like to stick with 22-24mm on the older Boras. I've used 25's on the old Boras but experienced the weaker bond in the middle upon removal.
Plus, fitting a 28mm tubular is still going to measure out at around 28mm when mounted, regardless of rim simply because it's the casing that determines it's ultimate size, and not dependent on how wide the rim beads are apart like they are in a clincher. The same clincher can measure very differently when mounted on a narrow versus a wide rim.

[mpulsiv]

23mm tires will be at scarcity in 2-3 years as the industry is going at full speed to increase tire clearance on all road bikes. 28mm is becoming the standard. With wider tires you can run lower pressure, increase comfort, increase traction and improve rolling resistance. Many would argue that 23mm is the aero king. Sure, that's because external width of any modern rim is between 24-27mm and isn't optimized for 25mm tires. Enve is the first one to push this out to ~30mm. Long story short, there's a delta of ~4.5 seconds (see #1 and #12 in the chart below) in 40k if you race and want every advantage, then 23mm is for you.

Source: http://flocycling.blogspot.com/2016/04/ ... study.html

[Calnago]

28mm may be the standard "clearance" they are shooting for, but that certainly doesn't mean that everyone will be on 28mm tires. I think the high end road bikes and peloton will settle on 25mm as the standard for the grand tours etc. And larger for the likes of Paris Roubaix, etc. Maybe smaller for TT's.

[eyedrop]

25c tires are all the rage nowadays. I think 23c still has it's place. They are more aerodynamic on most wheels vs. 25c, and lighter weight as well. Even though they are less comfortable, they do feel more racey to me. They offer less grip, but offer more turn in making it easier to flick in a corner. On a smooth surface, they feel super efficient.

25c is deffinitly more comfortable. They are perfect for rough roads, long rides, and just general riding . And there is plenty of evidence of lower rolling resistance and better performance overall. So in the end, what I'm trying to say is 23c feel faster to me, even if they are not... if you have ever been on 20c tires, you know what I mean. They just look and feel fast, especially on a smooth long incline.

[marshalus]

To all of you riding 25 Conti GP 4000 S2. What is the width of the tire after inflating. Is it 25 or it goes up to 27 or better?

Any of you with new zonda C17 with 25 Conti GP 4000 S2. How does it look and feel? Is there a ballon effect?

[mpulsiv]

To all of you riding 25 Conti GP 4000 S2. What is the width of the tire after inflating. Is it 25 or it goes up to 27 or better?

Continental GP4000S run wider and taller than anything else out there.
25mm measure between ~27mm. Here's the data for 23mm, 25mm and 28mm www.bicyclerollingresistance.com/specia ... i-23-25-28

[evan326]

On my aksiums, my 25mm gp4000 s2 are ~28mm at 90psi