Endurance, recovery, and strength decrease with age. No 70-year-old cyclist is going to "recover" while he's riding in the middle of a peleton! Joe Friel's Cycling Past 50 had a few off-the-cuff remarks about this, but it seems there might be better info available. Any observations or links?
There are a million variables, I know, I know - obesity, lung damage, heart condition, etc. But maybe there some general rules or guides.
I'm 65 & started riding last June - 7,500 miles so far (I'm retired). I used to run a lot (my 4 marathons were sub 3 hours) but I stopped when I had lost much of the cartilage in my knees at 55. So I had lots of first hand experience observing the effects of aging on my body up to 55. My main observation was that recovery slowed down quite noticeably around 50. I belong to two cycling clubs, and, FWIW, I find lots of VERY strong riders in their 50's, There are a number of solid riders in their 70's but they are not really strong riders, IMO. That said, I hope I am riding ten years from now as well as they are.