Now before I get laughed off the board, what are you looking for in a "good" cycling community? Excitement? Adventure? A chance to be a loner and outsider? Hilly terrain and hot, muggy weather? Then Atlanta's your town!
Seriously, the in town neighborhoods are booming and the streets are becoming much friendlier to biking, with dedicated bike paths and lanes and more convienent destinations. I'm an Atlanta native who recently moved back and I've been astounded by the recent positive changes. Once we get the Beltline bike-route finished, the in town area will be an awesome place to live.