Originally Posted by
jacobsever
You guys are running some pretty wide tires. I've never put anything wider than 23 on, except I borrrowed a 25 from a friend the other night, even that difference is kinda weirding me out.
Everyone is going to 25's for the road. Many pro teams have made the switch. There is a lot of hype around it and I decided to see for myself.
I purchased two pair Vittoria Rubino Pro III Slick tires, one pair 23mm and the other 25mm. I tried them back to back - same wheel, bike, tubes, pressure on the same day. Rode a few miles on the 23's, then switched to the 25's and back to the 23's. I could tell the difference in comfort and pedal effort as soon as I started pedaling the 25's. Going back to the 23's and I was like, "Why?"
The only downside is they are a bit tight sliding past the brake pads.
The technical reason has to do with sidewall flex and the length of the contact patch. The contact patch of either tire is equal in area but is wider/shorter on 25's and narrower/longer on 23's. More sidewall has to flex on 23's. Sidewall flex is what increases rolling resistance.
I wonder what kind of bike the OP has that he wants to run 25mm wheels.
-Tim-