I ride a 2002 Lemond Zurich with an Ultegra 53/39, 175mm Crank Arms, and a 12-25 freewheel. The rear wheel is a Bontrager Racelite. The RD is an Ultegra GS. I am 53 and and although I try to ride and train as much as possible the hills in NJ/PA seem to be getting steeper. I would like to increase my high gear to a 28 but all the 9 sp cassettes I see only go to 27. Can I put a 10 sp cassette with a 28 on the bike without much problem given my RD? Also, what would be the smallest chain ring I could use to replace the 39?