54 here. I'm not as old as some, but many think of me as 'old timer'. I abide by 'hard days hard, easy days easy'. I'm only good for two or so 'hard' rides a week, otherwise I'm rolling slow and easy. I enjoy getting out by myself, finding my own pace and getting lost in my head. Sped? I don't know; maybe 15-16 mph on rolling hills. The fall is my favorite time for it.. buy usually around December I start thinking about base training again.