The old 400K and 600K brevets from the Harvard, IL Brevet series ran that way 20+ years ago. It was tough when I was in my thirties. It would suck now in my fifties.
Did one 600K in 1991 and got caught in a bad thunderstorm coming into Barneveld. You ain't lived until the phone pole you are riding past gets struck by lightning and the shockwave from the INSTANT thunderclap knocks you on your a$$.
