I want to add Avid BB7 road disc brakes to a Lemond Poprad disc cyclocross frameset that I bought as a frame only. I hear that some of you guys are running 140 rotors on the rear and 160 rotors on the front. This is my 1st foray into disc brakes; how do you decide on the rotor size? What are the pros and cons? Will the hardware take either 140 or 160s? I am a big guy 220 lbs, so I was assuming 160s (the bigger the better).