The Ironman World Championship this October just lost its marquee name: Lance Armstrong.

Armstrong's recent entry into the world of combination swimming, running and bicycling endurance races looked like it was paying immediate dividends. Ever since he announced in February his goal of competing in the world's premier endurance event, anticipation had been building, spurring earlier-than-usual hotel reservations in Kona, Hawaii, where the race is held, according to Bob Babbitt, a pioneer of the sport who covers triathlon...