Front 23mm Back 25mm tyre

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audioblazer
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by audioblazer

If u have a tyre each 23mm & 25mm , which would you use for front or back . And why ? I have a pair of 25mm Conti GP4000S2 but when it’s pumped up it’s so tall that it touches my front caliper . The back tyre is fine . So is thinking of using a 23mm Conti for the front tyre but was told 25mm F /23mm B is better . So am puzzled with the 25F/23B combo

CLEAR
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by CLEAR

I have been running staggered tires on two of my older frames, mainly due to little space between tires and fork/brake arms. And secondly I prefer the zippy cornering response on both said bikes, front are Veloflex criterium 23 and Conti attack 22, Rear tires are 25mm veloflex and 24mm conti force respectively.

On some newer bikes, either 25/25 or 25/28 whichever suits the purpose either fast paced or slow group lazy sundays.

Seen 25F 23R on some Enves, the owner just prefer it that way he said front hits more bumps first, and matches the rims with better bulges.

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kgt
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by kgt

23 front 25 back. That's the right thing to do both in terms of aerodynamics and in terms of comfort.

alcatraz
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by alcatraz

Try to match the front tire with the rim width, if thats below 23mm or over 110psi then you have the wrong rim. If you're 75+kg I would modify "below 23" to "below 25". Ideally you want to stay around 90-100psi (depending on road surface quality) and if you get pinch flats often it means your tires are too narrow.

The same applies in the rear with regard to pressure. If the rear tire is wider than the rim by a little it's not the end of the aero world.

The fastest wheelset is not ultra wide rims. Only as wide as you need to support your weight at 90-100psi while mating well with the tire width.

If you're over 100kg 25c tires are probably too skinny. If you are 60kg 25c tires could be too wide, at least in the front.

AJS914
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by AJS914

audioblazer wrote:
Fri Jan 11, 2019 10:40 am
If u have a tyre each 23mm & 25mm , which would you use for front or back . And why ? I have a pair of 25mm Conti GP4000S2 but when it’s pumped up it’s so tall that it touches my front caliper . The back tyre is fine . So is thinking of using a 23mm Conti for the front tyre but was told 25mm F /23mm B is better . So am puzzled with the 25F/23B combo
25/23 makes no sense.

The GP4000 is a tall tire. FWIW, the GP5000 is truer to size and measures about 1mm less tall.

https://www.bicyclerollingresistance.co ... -5000-2018

So, if 1mm will make enough of a difference the GP5000 might be an option for you. Or just run 23/25 on the GP4000s.

mattr
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by mattr

Large front/small rear was a thing on MTBs a few years ago.
Lower front pressure for traction/comfort higher rear pressure for, well, cutting through slop and higher speeds.

Never really took off, not in any real sense. (mainly as it didn't work well.)
On a road bike, it's not even worth the effort.

(Conti force/attack are sold as a boxed set as well, 22F/24R)

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Calnago
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by Calnago

I prefer the symmetry of having both tires the same. Only reason I’d mix it up is if there wasn’t enough clearance somewhere, like under the fork crown. But even if there was a limiting clearance factor involved in that case I’d probably still match the two tires to the size that does fit. 25’s in a tubular are where it’s at for me, front and rear. Mixing it up is one step removed from having two different colored tires.
But I could see if you’re heavier, and a 25 simply won’t fit up front, then nothing wrong with the 23/25 combo.
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Hexsense
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by Hexsense

Conti Force iii / Attack iii are sold as boxed set, 23c front and 25c rear.

Benefit of front bigger than rear:
+generally you want more grip in the front. So bigger front tire at lower pressure if you need most grip.
+on bumpy terrain, some bikes are more harsh up front than rear, so wider front tire with lower pressure correct that.

Benefit of rear bigger than the rear:
+aerodynamically optimal up front: front tire need to match front rim width pretty well to make it aero.
+rolling resistance optimal in the rear: rear tire wider than rim is not as bad as front tire aerodynamically, but the rear tire support most of your weight so make it wide for low rolling resistance is good.
+Pressure balance: weight balance of road bike is like 40/60 front/rear. Normally you need lower pressure up front because it support less weight. Now since front tire is narrower, you can actually just keep them the similar or the same pressure optimally.

kode54
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by kode54

as mentioned by @CLEAR, i thought Enve had a wider rim up front and narrower in rear for aerodynamics...the rear trails the front airstream.
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audioblazer
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by audioblazer

Thanks for your feedbacks. My rim pretty wide- ard 26mm . I m not that heavy -68/69kg

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wheelsONfire
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by wheelsONfire

Motorcycles always run small front, large rear.
Not that i think you'd need it, but it helps when cornering.
Last thing is aerodynamics, for this you'd want the less wide tire in the front.
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kgt
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by kgt

audioblazer wrote:
Sun Jan 13, 2019 1:56 pm
Thanks for your feedbacks. My rim pretty wide- ard 26mm . I m not that heavy -68/69kg
At 69kg you don't need anything bigger than 23 front and 35 rear. At your weigh you don't need wide rims either. A narrowed profile wheelset would be better IHO (lighter, more responsive, more aero).

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audioblazer
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by audioblazer

Tq will try a 23mm GP4000s . Meanwhile I fitted a 25mm GP5k clincher without any issue . GP4k certainly has v much higher sidewall

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