When I ride with people IN my age group, (mid fifties) I am fast enough and have good endurance, I can hang
Then sometimes I run Into a machine, an engine of pain. I chase this giver of pain and never catch him/her, I can ride so hard I spend that night fighting cramps.
Some times this leg killer is older than me, sometimes younger..

Then I ride with 30 somethings and hang just fine..

My point ?

I only race,,, me !