Long time no post.. been riding the hybrid now for a couple months and it's been great. Figured the cadence thing out without and other mods to the bike and I"ve worked my way up to a 16.5mph avg over about 25 miles usually. Had a crash last weekend and broke the hangar for the rear derailleur, so I had to have that replaced. While the bike was in the shop I swapped on a set of Continental SuperSports in 700x28 sizing to replace the stock Bontrager 700x35's. Will take my first ride tomorrow with the new rubber. Initial impressions are good. The Conti's seem to be of good quality, noticeably light compared to the Bontragers, and virtually slick.

What expectations should I have regarding added mph by swapping the tires only?

Same output, same speed....................

1.25 mph

Speed: 1mph faster. Fun factor: way up.