Originally Posted by hophead
Yup, skinny tires are faster and the smaller the tire, the less effort it takes to make 'em roll.
To a certain degree. While going from a 32 to a 25 will offer less rolling resistance given a similar tread pattern, a smaller contact patch is not always a good idea.
Twenty years ago, we all thought the hot ticket was the 19mm tire. Problem with that is the contact patch went from being wide to long. If your weight is a constant, and your wheel diameter is a constant, then your contact patch will remain constant, (in area) regardless of tire width. So instead of that short, wide patch from the wider tire, you get a long, narrow patch with a skinny tire. And that long patch offers more resistance, as the tire changes shape slightly to conform to the flat ground.
For the record, the 700x23 was found to be the ideal size for racing.