Though I'm a huge sports fan, there are still athletes and events I don't know anything about -- until I see films about them in ESPN's 30 for 30 documentary series.

The Birth of Big Air just premiered in conjunction with the current X Games, and now I'm fascinated by high-flying BMX innovator Mat Hoffman, who reached astonishing heights in his Oklahoma backyard, but at astonishing cost.

Intimate gems like this are ESPN's gift to us for its 30th anniversary, distinctive documentaries from smart directors with a passion for subjects both small and epic, and this weekend offers a great chance to catch up. A five-hour 30 for 30 marathon Saturday on ESPN Classic showcases the range and idiosyncrasy of these films, which often tell us as much about other aspects of life as they do about the games people play.

(The Birth of Big Air isn't part of the marathon, but has its own repeat airings Friday night at 3 a.m. ET and Saturday at noon ET on ESPN2, plus Saturday at 1 p.m. ET and Sunday at 8 a.m. on ESPN U.)

Here's Saturday's 30 for 30 marathon, July 31 on ESPN Classic (all times ET):

12 noon -- Run Ricky Run, a preconception-challenging portrait of NFL running back, pothead and independent thinker Ricky Williams.
1 p.m. -- Guru of Go, recalling how coach Paul Westhead perfected a new run-and-gun offensive system with ill-fated college star Hank Gathers.
2 p.m. -- June 17th, 1994, a look back at a confluence of sports and society the night of O.J. Simpson's infamous "slow speed chase."
3 p.m. -- Straight Outta L.A., where director Ice Cube examines the intersection of the NFL Raiders' 1980s move to Los Angeles and the burgeoning of hip hop culture.
4 p.m. -- Winning Time: Reggie Miller vs. The New York Knicks, tracing how the Indiana Pacers star turned into NYC's greatest sports villain.