MinnMan

Such a complex and fraught question. As others have said, it's probably time to quit when your balance or awareness make you a danger to yourself or others, but as cycling is not a safe sport at any age, that threshold is somewhat arbirtary or in the eye of the beholder.

The other part is that we have to be lucky with our health, and particularly with our orthopedics. When cycling brings more pain than pleasure, it might be time to quit.

I'm 58 and I don't yet wonder about when I'll have to quit altogether, but I do think about the age at which there are significant losses in performance. At this point in my life, riding long and fast is important to me. It's not just that I get pleasure from doing so, but it also is the circle of friends with whom I ride. They are my riding family and in general they are younger than me (though not all). I do not look forward to the day when I will have to admit that I can't keep up.

There's a fellow in that group who is about 68 now. Some years ago, at 63, he was formidable. Now he stays in the back. And he doesn't come out to ride so much any more. There's another who is 64, and a very important person to all of us. I see him losing his speed and I wonder how many more years he'll be riding with us.

On the other hand, I know a guy who is 73 who this summer did a 10 mile time trial at a 23 mph average. I hope I have his health and vigor at that age, but I know that the odds are against it.