17mm or 19mm rims?

[uraz]

It does not matter but: 75-80 kg, 6.5-8.0 bar.

[Marin]

The 2 images images are fantasy, the cross section will be circular in both cases.

[uraz]

Cross section of a tire will change along with growth of its measured width but illustration is of course an exaggeration. I wanted only to show why stretched tires don't corner as good as they should.

You can spread tire beads by hand beyond it's natural width and see how cross section changes and most importantly what happens to part of a tire which is responsible for cornering.

[Alumen]

It does not matter but: 75-80 kg, 6.5-8.0 bar.

Hence 25mm is best on 17C

Btw... I ride 23mm on 17C... similar as 25mm on 19C... ride quality is just great on my front wheel.

[cdtf]

Cross section of a tire will change along with growth of its measured width but illustration is of course an exaggeration. I wanted only to show why stretched tires don't corner as good as they should.

You can spread tire beads by hand beyond it's natural width and see how cross section changes and most importantly what happens to part of a tire which is responsible for cornering.

No. The cross section is circular, period.

You spread bullshit, and you should stop doing so.

When you spread an tire by hands, as you say, you lack the most important parameter, aka air pressure, that will make the casing totally round, as the casing of bike tires is in no way capable of resisting against the pressures used.

Stop talking please.

OP, get the 19c rims.

[uraz]

Btw... I ride 23mm on 17C... similar as 25mm on 19C... ride quality is just great on my front wheel.

Did you try to ride the same 23mm on a 13c or 14c rim? Do you have a comparison?

[...] You spread bullshit, and you should stop doing so. [...]
Stop talking please. [...]

Yep truth sometimes hurts, especially if someone is fed by marketing department stuff...

If you don't like my illustration here is another one:

[Hexsense]

Even if you would like to use wide tires (28c) you should not but very wide rims. 17c rim is a reference width for 28c tire. This relatively new trend of using 19c (and up) rims for narrow road tires is in my opinion not worth it's slight aero advantage and cool appearance. Stretched tire will cause your bike to corner like a trans ocean oil tanker (slow and hard to manage).

With 28mm tyres (or in reality 32mm), you have that behaviour, even on 19mm rims, but once you switch back to Power comps or GP4000s in 25mm, it rides like a charm, even better than on 17mm IMO, but as stated, you have to drop 10psi to account for the higher air volume in 19mm vs 17mm.

me used 23c (conti 4000sII) on 21mm internal width don't quite agree that it become bad too. It's alright, just like a normal 23c. But not as good as 25c even though it's already wider than 25c on narrower rim.
But 25c on 21mm is on rail. It's rock!
my current set-up is 25c on 21mm internal width at 65psi (this pressure is higher than necessary already)

[Beaver]

It does not matter but: 75-80 kg, 6.5-8.0 bar.

Did you do this picture by yourself? Sorry but it's completely different to what I and others have experienced on the road. Cornering is better with a wide rim as long as the pressure is reduced. With 25mm tires on 21C rims 5 bar would be enough for your weight. And nothing feels sluggish as the tire walls nearly "stand straight"...

With your logic motorcycles would be non-rideable...

[uraz]

Yes illustration (with white background) was made by me just to show how shape of a tire is affected by using wider rim. It's not a technical drawing and of course it's not 1:1 with reality. Nontheless, just think, how is it possible that the same tire is wider (mesured with a calliper) on a wide rim than on a narrow one. Tires don't grow like inner tube. When it's getting wider it must also get flatter on top to provide some "material" to width expanditure.

Motocycle tires are wide but they are designed to be like that and they are mounted on a rim with a desired width. Curvature of a top section is untouched. Also front tire is much narrower and rounder than the rear one (in track motocycles).

Please tell me what are you referring to by saying cornering is better on winder rim? Do you mean grip is better or bike agility is increased?

[Marin]

By using a wider rim, you are just adding to the circumference of the tire, making the diameter bigger in all directions, so it will be wider, taller and also bigger diagonally if you want to measure that too.

[Beaver]

My "real world" experience with 25mm Conti 4000S II on 21C:




The tire gets wider at over 28mm but not taller - still 25mm...

Cornering is better than with a 23mm tire on a 17C rim - both for grip and agility. But only with reduced pressure.

I ran 25mm tires on 15C before: with low pressure sluggish, with high pressure too much road buzz.

25mm on 21C is the best solution for me and I won't go back to narrower rims.

[uraz]

For reducing road buzz I have switched to road tubeless (23c on 15c rim). Before that I was using 23c GP4000s on 14c rim and than switched to new wheels that were 19c (internal) still using same tires. I could not accept this setup. Maybe 25c tires would help but in a meantime I have changed whole bike so I didn't verify that.

[Hexsense]

For reducing road buzz I have switched to road tubeless (23c on 15c rim). Before that I was using 23c GP4000s on 14c rim and than switched to new wheels that were 19c (internal) still using same tires. I could not accept this setup. Maybe 25c tires would help but in a meantime I have changed whole bike so I didn't verify that.

did you properly reduce pressure by about 20psi going from 14c to 19c ?
That matter a lot.

[TonyM]

Interesting articles on rim width and tire width I just read:

http://engineerstalk.mavic.com/en/the-r ... rim-width/

and


http://www.roadrevolution18.dtswiss.com/endurance/
as from the "the graph facts"

[Marin]

@Beaver which brakes are these?