AMA Supermoto Championship Motocross and road racers converge in this Las Vegas finale to determine the two-wheel king. X Games supermoto gold medalist Ben Bostrom (right) defends his title.
Urban Challenge Nationals Two-person teams must solve clues to find 12 hidden checkpoints in Miami. With a winning pot of $50,000, the 300 racers can phone friends (make sure they're smart) to help unlock the answers.
Touching the Void PBS airs this documentary on two climbers' efforts to survive in the Andes. Its haunting question: To save your own life, would you cut the rope holding your friend and let him fall to almost-certain death? (9:00 p.m.)
Giants of Rio Relay Race Entrants, including Ironman stud Tim DeBoom (right), compete on four-person relay teams, taking on a 2.5-mile swim, a 28mile jungle bike ride, a hang glide above the city and a 10-mile sand run.
JEFF GROSS/GETTY IMAGES (MOTORCYCLE)
TRACY FRANKEL (RIO RELAY)