...and what a difference. I've spent lots of time trying to figure everything out. I learned that my Michelin Power Cup 25 mm tires are actually 28.5 mm wide when fully inflated . I actually weighed my bikes. I was riding a late-90's Scapin Pro Racer with alloy wheels that have a 17 mm inner width on very smooth roads at about 90 PSI. Felt fast. But my little bike computer told me a very different story today after I inflated to 76 rear and 71 front. The acceleration didn't feel as fast, but I was really rolling once I got going. I have to get more scientific, but it appears that I was hitting speeds over 2 mph on certain parts of my ride more than when I was riding higher PSIs. Oh, and the practice of placing the hands on the hoods, lowering the head forward, and compressing the arms/elbows inward made a huge difference. You can see the speed jump when you get into that aero position. Really amazing.