Tire talk 23 vs 25

Discuss light weight issues concerning road bikes & parts.
Greatestalltime
Posts: 70
Joined: Sun Jul 02, 2017 12:47 pm

by Greatestalltime

Help me out on this please. I know there’s plenty of discussion on the subject of 23-25mm widths. I’ve tried both and I’m not sure if I should switch back to 23mm. I’ve been on 25mm for a few years now and do like them, but I ride at the same pressure so don’t notice more comfort. Just maybe more protection over bumps and bottoming out.

I’m on c-24 and c-40 clinchers on each bike. So they’re both, some say, too narrow for 25mm which leads to the “Ice cream cone” effect.

I know the 25mm has less rolling resistance, but when you factor in the drag on this setup is it worth it? (Plus it doesn’t look great imo) Yes. I know worth it likely means very little gains, but work with me, I want the best setup I can get.

Been using 4000s on one bike 5000 on the other and I’ll likely stay the same.

What are most of you running on these more narrow older wheels with 20.8 width?


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CrankyCarbon
Posts: 78
Joined: Tue Aug 13, 2019 1:15 pm

by CrankyCarbon

There's been a lot written about this.
23mm seems best for speed/comfort on 15C rims (the inside diameter).
25mm seems improves the comfort on 17C rims
but 25 on 15c is improved comfort but worse speed/handling as you are mentioning.

this excludes aero, pressures, etc.
I run 23mm Vittoria Corsa on Mavic Open Pros, which are 15C. I also only run 23mm on my older rims/wheels.
and I run 25mm Vittoria Corsa G+ on Fulcrum Competizione 17C

by Weenie


petromyzon
Posts: 432
Joined: Mon Apr 05, 2010 4:14 pm

by petromyzon

I don't think the aero profile will be that great with a 23c tyre on a 21mm outer width rim like the C24.
I run larger tyres because I like to run lower pressures - you can see from the tests on BRR that if you set up the same tyre in different sizes with different pressures to get approximately the same "sag" with each you get the same CRR.
If performance is really important to you you should invest in some wider wheels and run a 23mm max on the front.
If you want to stick with the same wheelsets I wouldn't worry about it, other than to say c24 rims are quite easy to dent if you do bottom out.

Greatestalltime
Posts: 70
Joined: Sun Jul 02, 2017 12:47 pm

by Greatestalltime

CrankyCarbon wrote:There's been a lot written about this.
23mm seems best for speed/comfort on 15C rims (the inside diameter).
25mm seems improves the comfort on 17C rims
but 25 on 15c is improved comfort but worse speed/handling as you are mentioning.

this excludes aero, pressures, etc.
I run 23mm Vittoria Corsa on Mavic Open Pros, which are 15C. I also only run 23mm on my older rims/wheels.
and I run 25mm Vittoria Corsa G+ on Fulcrum Competizione 17C
So those tests don’t have 25mm on 15c rims? Thanks I guess I missed that.

So I’m thinking I will go back to 23 until I upgrade wheels. I never thought the 23 were uncomfortable as actually like high pressure on either tires size-like 120psi plus


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Greatestalltime
Posts: 70
Joined: Sun Jul 02, 2017 12:47 pm

by Greatestalltime

petromyzon wrote:I don't think the aero profile will be that great with a 23c tyre on a 21mm outer width rim like the C24.
I run larger tyres because I like to run lower pressures - you can see from the tests on BRR that if you set up the same tyre in different sizes with different pressures to get approximately the same "sag" with each you get the same CRR.
If performance is really important to you you should invest in some wider wheels and run a 23mm max on the front.
If you want to stick with the same wheelsets I wouldn't worry about it, other than to say c24 rims are quite easy to dent if you do bottom out.
Are you saying go less than 23mm on a c-24 and definitely don’t go wider until I get a wider rim?




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bm0p700f
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by bm0p700f

first not all 23mm tyres are tue 23mm and the same goes for 25mm tyres. then there is rim internal width and tyre wall thickness that affect size so generalistion are difficult suffice to say none can be made beyond the 23mm tyre is probably the most aero and maybe the lightest.
Since the rim is not aero this is all moot anyway. splitting hairs.

Greatestalltime
Posts: 70
Joined: Sun Jul 02, 2017 12:47 pm

by Greatestalltime

bm0p700f wrote:first not all 23mm tyres are tue 23mm and the same goes for 25mm tyres. then there is rim internal width and tyre wall thickness that affect size so generalistion are difficult suffice to say none can be made beyond the 23mm tyre is probably the most aero and maybe the lightest.
Since the rim is not aero this is all moot anyway. splitting hairs.
Isn’t the c40(really c35mm in clincher) somewhat aero? And doesn’t that come effect negate that? Or is it not really aero enough that the tire makes not difference.

One test had the rolling resistance less on a 25mm because it’s patch was wider but shorter and overall less contact and less resistance.

Bottom line:You’re saying go with 23mm for these 20.8 internal diameter wheels?

Thanks for help


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Renault78law
Posts: 15
Joined: Fri Aug 24, 2018 6:56 pm

by Renault78law

Run 23 in the front, 25 in the rear. It’s a good compromise.

RocketRacing
Posts: 947
Joined: Thu May 10, 2018 2:43 am

by RocketRacing

Non aero rims? Run the widest tire you can that gives you the comfort you desire. As tires get wider, remember to drop the pressure, or you will be in for a less comfortable ride. Lots of charts on theis. I like the sram tyrewiz app for a baseline

Aero rims: Feel free to do the above if you don’t mind losing some watts (or most if not all aero benefits of your wheels). But if you have aero rims, why not take advantage of their design purpose. follow the “rule of 105” and chose a tire that when mounted on your wheel, is not wider than the widest portion of the rim (rim must be at LEAST 105% width of tire to see any real aero gains from sailing). Even better, one that is no wider than the brake tracks. Balance that with increased pinch flat risks with smaller tires. But not everyone runs the cobbles at flanders at 60k. I prefer to avoid potholes.

I run 25c gp5000. They measure pretty close to labeled (unlike the 4000’s that were 27+mm wide). Right now at 70psi, my broken in gp5000’s measure at 25.5mm, which is good for my 27.5mm outer diameter aero rims. A 23c gp5000 up front would be even more aero.

Squashednuts
Posts: 528
Joined: Tue Apr 25, 2017 11:12 am
Location: Christchurch New Zealand

by Squashednuts

Renault78law wrote:
Thu Aug 15, 2019 1:07 am
Run 23 in the front, 25 in the rear. It’s a good compromise.
+1
It’s what I started a wee while ago
I’ve not noticed any difference in levels of comfort

I’m currently toying with make and model of tyre as I suspect this will affect speed and comfort equally as much as width
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Sold -
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Pinguin
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Joined: Fri Nov 02, 2018 9:28 pm

by Pinguin

Renault78law wrote:
Thu Aug 15, 2019 1:07 am
Run 23 in the front, 25 in the rear. It’s a good compromise.
+2

petromyzon
Posts: 432
Joined: Mon Apr 05, 2010 4:14 pm

by petromyzon

I wouldn't go less than 23mm, you would have to run high pressures and unless your roads are perfect that will slow you down and tire you out.
I'm saying run 23 or 25, don't worry about it and ride your bike. If concerns about front wheel profile and aerodynamic performance are important to you then you should buy some new wheels with a more modern profile and run 23mm front tyres.

Nefarious86
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by Nefarious86

At 120psi in either I can't imagine anything remotely approaching a comfortable ride and you will be losing more energy from over inflation and bouncing down the road than the aero penalties. Are these race wheels? How much do you weigh? These two facts will have more of an influence on tyre choice on These rims than the aero interaction.

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3Pio
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Joined: Wed Mar 09, 2016 7:13 pm

by 3Pio

Im using 25mm tubulars on Bora wheelset, but on my Shamals (15C), definetely prefer 23mm Conti 4000 over 25mm.. I even ride sometimes attack/force tires (22mm fron/24 rear), and not finding them uncomfortable or something (on 4000 23mm and Shamals i rode few >200km rides in last two months).

Dont like 25mm because of bulbous shape, and instability feeling.. And dont need more comfort then 23mm provide me (i use Latex Inner tubes if that change something).. Those wheelset i ride on Alloy Frame (CAAD12), using Alloy Handlebar)....

by Weenie


PeytonM
Posts: 57
Joined: Wed Apr 24, 2019 10:59 am

by PeytonM

I have the same da24 rims. Best combo I’ve found for this wheel is Michelin power comps in 25mm size. Forget aero with these wheels.

Currently they are my spare wheelset and are set up with gp5s in 28mm that have done about 2000km on my other race wheels. Comfortable and reliable.

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