The other day, I counted up my 2017 year to date tally:
10 Metric Centuries & 1 Imperial Century.
All were unsupported and with just 1 or 2 friends.
Tomorrow I have Metric # 11 planned with 3 friends.
My age: 54
I have ridden 14 double centuries, but only 1 was when I was over 50, the rest were in my 40's.
My many Metrics, and occasional Imperials, keep my long distance instincts satisfied pretty well these days.