Originally Posted by
kahn
Talk to those 70 year olds still riding. And, of course, I will throw anecdotal "evidence" that human tissue: ligaments, tendons, muscle, cartilage and bone only have so much life to them. Same hip replaced twice (no accidents or specific trauma) and lots of friends "running" with new knees and even a few ankles. Yes, legs and cardiovascular systems are not standard but many have a "use by date!"
I will be 83 this year, and what you say doesnt apply to everyone. I ride anywhere from 20 to 35 miles every other day. I ride at a cadence that feels right, probably averages out to about 75 rpm. I mash up short hills and shift down on longer ones.