I have met a few 70-something cyclists and triathletes, and have read about some as old as 90+. I also follow the career or Sister Madonna Buder, the 70-something Spokane-based nun who keeps setting age records in the Ironman.
By the way, I strongly recommend the book, "What's Age Got to Do With It?" The author, 40-something Kelly Ferrin, is an enthusiastic speaker and gerontologist.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069