that page says you can do "From the approachable (and reasonably flat) 22-mile Piccolo Fondo, to the hilly 71-mile Medio Fondo and the challenging 101-mile Gran Fondo that serves up 6,500 ft. of climbing"
then further down it says "The Gran Fondo Virginia offers three routes of 22, 52 and 102 miles."
22 miles, especially flat, is hardly worth doing, 71 is a bit much. 52 could be good if it's really an option.