Several of you had comments about specific athletes who are spectacular. I find them in almost any endeavor, but I was really asking about general rules of thumb. And, I have read Cycling Past 50. But I found his focus too much on formal competition.

Several of you said essentially, just enjoy doing what you can do. I agree totally and utterly. Today's ride was joyous, despite being very slow and having to deal with a sticking rear brake. It is not as exhilarating at 14 mph as it is at 19, but it still is exhilarating! Talking to other riders I ran into was a joy. Stopping at the LBS and having the head mech diagnose the rear brake and toss me two spoke nipples for free made me all warm and fuzzy (my last visit he had me take his one-month-old personal bike out for a few miles so I could check out the electronic shifting and the latest brakes).

I just finished comparing my best ride of the last few weeks to the same ride when I was at my peak, 2 years ago. I had lost 30#, I was fit, I had just done a PR on a 51-mile group ride where I rode with the fast boys for the first 11 (flat) miles - over 19 mph average, and I took my share of leading. They disappeared with a smile when we hit the hills, but I ended up at 17.2 average for 51 miles (41' average ascent / mile). I was coming up on my 67th birthday. Stoked. Medical problems triggered weight gain, chemo didn't help my fitness, and then last year I broke my hip and needed a replacement.