Originally Posted by
tjspiel
Before you get those 1.25 inch tires...
The other thing to consider is ride quality. You're going to feel the bumps more with 1.25" tire, especially on a 26" rim. You're going to have to be much more careful about keeping the air pressure up and you may have more issues with flats.
And in the end, the bike is still a hybrid/comfort bike. The performance gains you get by going with a narrower tire may not be what you hoped for.
This. At about 20 MPH, your chief obstacle is wind resistance, so putting skinny tires on a hybrid might just hurt the ride without giving you more speed.