Metro50

What's up guys.

I have a set of 2014 Shimano C35 clinchers on the way and because Shimano's widened the gap
to 21mm I was curious if anyone had experience on riding these with either 23 or 25mm tires?
And, which one is preferred along with the pros and cons.
Or is it negligible?

All comments are welcome.
thx!

dtrain

25 ftw

alexaschwanden

23mm are faster.

gregf83 

The advantage of 25s is you can run them at a lower pressure so a little more comfortable ride. Rolling resistance of 25s is often less as well although this may be offset by slightly worse aero performance due to the wider profile. For training and day to day riding I think 25s would be slightly more comfortable although depending on the roads you're riding on the difference is minimal.

deacon mark

No I will take my 23's they roll well with my Bdop wheels I build myself. 25's are too wide for my taste and either Vred Tri comps or Conti gp4s

Lazyass

Only in your head.

Bunyanderman

23's look cooler.

FBinNY 

I gather that the 21mm dimension is outside width, so either 23 or 25 will mount. Also keep in mind that tires aren't very true to nominal width so some 25s may be smaller than some 23s.

Otherwise, unless you're very light, I'd opt for the wider of the two (actual width).

Number400

Try them both out. I run 25's around here in the winter and have 23's on different bikes. I think most people couldn't really tell the difference on the road.

jaxgtr

I run Michelin 25's on my Boyd's and they size out to almost a 28, but I like that. I can run lower pressures and improve the ride over the 23's, but at the same time, the 23's size out to almost a 25 and I have to have a little higher pressure in them and the ride is just a tad bit harsher.

98koukile

I have RS80s in the C24 profile and they are awesome with GP4000s' in 25mm. I had 23s on initially and I feel the difference is enough to never buy them again if I can help it. If your frame can handle the clearance (mine can barely fit these) I say go for it, the worst that happens is you switch back and have an educated opinion on whichever you choose in the future.

BillClinton

Finally, something original.

znomit

25s are nearly 10% wider than 23s.
Thats 10% more junk you'll run over.
Thats 10% more flat tyres.

Someone prove me wrong.

I generally run 25s for comfort but we have chip seal roads here.

FLvector

^^ This might be true, but if so, it would also stand to reason that 25's should give you more miles due to the larger surface area. The bigger contact patch, especially if you run them at lower psi should distribute the weight on a bigger surface, giving you more miles before the tire begins to loose the profile and wear down to the cords.

I try to do a visual inspection a few times/week to look for any embedded glass, etc. and pick it out before it has a chance to go deeper.

jbchybridrider 

I think the wider tire is faster is all in the head. Having the tire width matched with the appropriate pressure it works out the same.
I have always used (on road bikes) 23mm tires at around 110psi but then found some quality 20mm tires cheap so took a chance and there magic to ride at 140psi but I use them on a steel frame and fork probably how they were traditionally used. I have a feeling tires got wider as frames got stiffer ?

znomit

Actually the contact patch size only changes with pressure. PSI=Pounds/Sq Inch. Pounds = you and the bike, sq inches = contact patch area.
/physics lesson

FLvector

So are you saying that a 23, 25, 28, 32's all have the same contact patch at equal pressure?

GravelMN

IMHO

I have ridden 23, 25 and 28s and find that my overall speed on a 20+ mile ride doesn't change much. More important than the width (volume) of the tire are its quality and construction, as well as running at the proper pressure for the tire. I've had supple, high quality 28s that rolled better than mediocre 25s or 23s.

I'm a Clyde and ride under a wide variety of conditions and I personally find that when I run 23s at pressures high enough to prevent pinch flats on rough roads I feel more road vibration and they feel skittish on anything other than smooth, dry, good pavement. I find that under my typical riding conditions, I'm more confident and aggressive (not to mention comfortable) with 25s or 28s so my overall speed is as good or better with the wider tire. As long as we are talking the same brand and model of tire, my personal preference is a 25mm for most road riding as I find the slight weight increase is offset by better rolling on imperfect surfaces + I get less fatigue from fine road vibration. For long rides and/or rough road conditions, I have no problem with 28s though my current road bike barely clears them.

https://www.schwalbetires.com/tech_in...ing_resistance

Metro50

Hey thanks for all the inputs guys.
I found a really good thread why 25's are the way of the future.
Alex and Deacon I found out that more pros have started converting from 21 to 23 to 25mm now.
Looks like this has been a myth that has sunk into our decision from long ago.
Thinner, lighter & more aerodynamic should be faster right?
Evidently not.

The 23mm for ex: are more V shaped thereby adding less rolling efficiency and harder pedaling.
The 25mm are more U shaped which conforms a shorter contact point on the ground equaling faster rolling.

Have a look>>>

25 vs. 23 | Is Wider Really Faster? | Competitive Cyclist

Metro50

Jaxgtr I noticed you run Michelin 25's which coincidentally am looking to get the Michelin Pro 4 service course in the 25's also,
but hear they look as wide as a 28mm is this correct?
Found a similar thread that one rider mentioned this also but resulting in a 27mm look.
If this is the case does it look like the tire comes out past the rim wall?
Any vindication?

thehammerdog

25c are the future.....what you riding?

Bunyanderman

I have run really crappy 28's before, ran them at 100psi and they would chatter my teeth. I put on 23's (tubular) and run them at 120psi and the ride is still much better. I think tire quality matters more than size.

achoo

Even IF true, the higher pressure of smaller tires is more likely to force things like pieces of broken glass or other sharp road debris all the way through the tire...

achoo

If you assume the weight supported is the same, assume an ideal infinitely flexible and infinitesimally thick tire body, and neglect the tire drop reducing the volume inside the tire and the resulting compression of the gas in the tire, that's EXACTLY correct.

Contact patch = weight / tire pressure

PeteDman

I run 25 in the back and 23 in the front. I get the comfi ride from the back at lower psi and the aero of the 23 on the front.