So my brother has a half way decent road bike, Trek 2500 - it was the carbon with aluminum lugs bike, late 80's. The only thing is that it has some tank wheels with a 7 speed setup. I have a decent set of Bontrager wheels sitting around that has a 9 spd cassette. The rear wheel fits in his frame, I was surprised. So my question is this: can I swap the wheels, give him the lighter Bonti wheels, and figure out how to make the gearing work? Can we go with the 9 speed cassette and not use two of the gears? Or do we need to upgrade the front/rear derailers for 9spd setup? Thanks,.