25mm tires. Faster than 23's for 100 KG rider?

[PeterF]

I have been using 26mm tires for the winter since the cold weather in the Northeast US has opened up some pretty big holes and cracks in the roads. I like the extra cushion to smooth out the roads. Apart from the smoother ride, I'm not entirely sure if they are slower. In fact they may be faster for me. I am a larger cyclist at 100-103 kg. The 26mm tires I'm using are not a race tire, but yet they seem to corner well and roll nicely. I'm considering using these in the summer and rotating out my 23's for 25's. Thoughts?

[kdelong]

The common theory is that because the 26mm tire usually has a larger contact patch than a 23mm or a 25mm tire, it will also have more rolling resistance. When you start talking about specific tires, this theory goes right out the window. There are a lot of variables that effect the size of the contact patch and rolling resistance. Contact patches and rolling resistance of the same size tires varies from tire to tire, depending upon the design of the tire. Without getting too long winded here and venturing into subjects that I am not qualified to comment on, I'll just say that you should ride whatever feels best to you. Just remember, it is not the tire, or any part of the bike that makes you faster. It is YOU that makes you faster. You're doing the right thing though, riding through the winter!

[frenchyge]

Tire construction plays a bigger part than tire width, but for the same model tire the wider choice could well be faster. There's a great discussion here: http://www.slowtwitch.com/mainheadings/techctr/wheels_tires.html

[artemidorus]

For track or very good quality roads, a smaller tyre at higher pressure will be faster. On rough roads, where you will bump around a lot at a tyre pressure high enough to prevent pinch flats at your weight, you would probably be faster with the 25mm tyres at a lower pressure.

[Phill P]

This is a very interesting point, and I agree with KDELONG. Ride what works for you.

Look at Roubaix, they ride 25-28mm tires because they believe it makes them faster. Not only do they not fatigue as quickly and corner better, but the tires will roll over the rough roads faster. Same with MTBs. They went through a phase of narrow higher pressure (6kpa) racing tyres, then went tubeless and bigger with low pressure was better.

Rough roads makes a different equation, I don't know if weigh makes that much difference, air pressure would account for weight changes.

[oldbobcat]

I think the theory for heavier riders going faster on fatter tires has to do with the pressure at the contact patch. The fatter tire, with a larger contact patch, exerts less pressure and hence less friction and less rolling resistance over the road. This seems plausible but I've never seen the numbers or done A-B testing.