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Yes, if you are the type of person who watches where he rides. If it bothers you, you can also ride a 23 in front and a 25 in back. (some frames will not fit a 25 in back because of a low brake bridge)
 

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Specialized is making a tire called the Roubaix that is a 23/25. It is a 25mm casing tire with a smaller contact patch. It all may be hype, but I really like using them on long rides where comfort matters as much as rolling resistance. It has a puncture resistant belt and is light enough.
 

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bigbill said:
Specialized is making a tire called the Roubaix that is a 23/25. It is a 25mm casing tire with a smaller contact patch. It all may be hype, but I really like using them on long rides where comfort matters as much as rolling resistance. It has a puncture resistant belt and is light enough.
Since contact patch area is a strict function of load and pressure, how do they claim this is being acheived?

For example, a tire carrying a 100 pound load and inflated to 100 psi will have a contact patch area of... wait for it... 1 square inch. regardless of construction method, width, diameter, or any other factor. So long as the tire remains pneumatic (air-suspended) this will be true.

I'm calling BS on Specialized here....

--Shannon
 

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I am a 203 lb.rider and have ridden many a 700x23 with no pinch flats.I run 100 psi for better ride quality.There is nothing wrong with 25s but they are much harder to find on sale in a folding race tire.Some 23s are wider than others-my favorites are Michelin Pro Race or Carbon.The Carbons have been on sale lately for 20$ before discount codes or Team Performance rebates at Performance Bicycle.
 

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I'm also north of 200lbs and for years have mostly ridden Conti Ultra 2000s 700x25s which actually measure much closer to 23. I run them at 110-120psi and I don't think I've had more than half-a-dozen flats in a dozen years.

My new LeMond has Bontrager 25s, which are more true to size. They look like touring tires, compared to the Ultra 2000s.

Jordan: that's good to know about the Michelin Carbons. I've been considering trying a set of those and wondered how close they measured to their nominal size.
 

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Specialized Roubaix 23/25 tire

bigbill said:
Specialized is making a tire called the Roubaix that is a 23/25. It is a 25mm casing tire with a smaller contact patch. It all may be hype, but I really like using them on long rides where comfort matters as much as rolling resistance. It has a puncture resistant belt and is light enough.
Well, Specialized isn't actually claming that the Roubaix tire has a smaller contact patch - what they are saying is that it has a narrower tread. Here's the blurb on the Roubaix web page:

"For these riders, we’ve introduced the new S-Works Roubaix open tubular with its comfortable large volume 25c 290 TPI Gossamer Spun Casing, merged with a fast-rolling 23c width dual compound Dual Radius Tread (DRT)."

In other words, they have taken the same tread (size and width) usually used on a 23mm and bonded it to a 25mm casing. This of course doesn't change the size of the contact patch, but it does decrease rolling resistance. The source of rolling resistance is hysteresis losses in the flexing of the tread and casing. Since most of these losses are in the tread, using less tread material will decrease rolling resistance. Of course, it also decreases tire life and puncture resistance as well.
 

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I'm right around there (225 in January -> 195 now!), and haven't had pinch flat trouble with 23c tires, actually, my only pinch flat happened on a 25c, gatorskin at that! Not much you can do about michigan potholes that the people in front don't call out :(
I think with proper inflation there is no problem running a 23c tire at that weight. I'm still going to run the wider gatorskins for training, but won't worry about the skinnier race tires.
 

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Mark McM said:
Well, Specialized isn't actually claming that the Roubaix tire has a smaller contact patch - what they are saying is that it has a narrower tread. Here's the blurb on the Roubaix web page:

"For these riders, we’ve introduced the new S-Works Roubaix open tubular with its comfortable large volume 25c 290 TPI Gossamer Spun Casing, merged with a fast-rolling 23c width dual compound Dual Radius Tread (DRT)."

In other words, they have taken the same tread (size and width) usually used on a 23mm and bonded it to a 25mm casing. This of course doesn't change the size of the contact patch, but it does decrease rolling resistance. The source of rolling resistance is hysteresis losses in the flexing of the tread and casing. Since most of these losses are in the tread, using less tread material will decrease rolling resistance. Of course, it also decreases tire life and puncture resistance as well.
I have 1200 miles on mine and haven't had a flat. They seem to be pretty tough while still providing a good ride. They replaced some vredensteins that were showing threads. Will probably get a flat for posting this.
 
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