I'm 250lbs and went with a disc trucker with avid bb7 road and STI shifters. Did a tour from nyc to joplin and had PLENTY of braking power with std 160mm rotors. Can't imagine anyone having any need to go larger. I estimate I must have been at about 340lbs total weight including the bike and the panniers. anybody much heavier than that aint getting up the hills that you need the brakes for!