“If you had too much personality, if you were too much of an individual, you were not going to have a factory ride,” said Paul Taublieb, motocross sport organizer at the X Games. “And if you don’t have a factory ride, you’re not going to win. It’s not a secret that factory rides have equipment that put them in a position to win.”  Stewart, of Haines City, Fla., who rides for Team San Manuel Yamaha, bucked that tradition by first establishing himself as transcendently fast. A two-time AMA Supercross champion, he was the favorite to win the X Games Moto Super X race Saturday at the Home Depot Center in Carson, Calif. But he crashed during seeding for another event, the Moto X Super Moto race, on Friday morning, injuring his shoulder, and will not compete in any more events at the X Games.  For Stewart, the injury means a missed chance to introduce himself to a new audience.  On his official Web site, Stewart said that he had injured his left shoulder, and added: “Yeah, I’m hurting pretty bad right now. It is very, very painful, and I can’t lift my shoulder above my side at all. If I could ride the bike I would, but there’s just no way at this point.”  Travis Pastrana, a retired racer who competes in freestyle motocross at the X Games, spoke admiringly of Stewart: “He’s the fastest rider who’s ever thrown his legs over a motorcycle. He makes amazing riders look stupid on a daily basis.”  Stewart’s demeanor on the track has added to a war of words with the sport’s No. 2 racer, Chad Reed. “Until the other guy starts beating you with consistency, it’s not a rivalry,” Stewart said. “Chad’s the type of guy, if he can’t win, he’s O.K. with being second. Where if I can’t win, there’s problems.”  Known for his hard-charging style, Stewart either wins or crashes, as he did Friday. He missed the 2008 Supercross season after injuring his knee in a crash. With Stewart out, Reed won the title, setting up a showdown in 2009. Stewart fell during the season’s first race, then won the next seven before falling in the eighth and losing the points lead to Reed. Stewart won four of the final eight races to claim the season championship.  During his career, Stewart has won 95 percent of the races in which he has not fallen.  “I don’t take second place,” he said. “I always try to win it.”  As part of a new generation of riders, Stewart has shown more in common with the showmanship of the freestyle motocross movement than with the old-school racing establishment.  “He’s sending the message to the traditional motorsports world and the action sports world that he could be that real bridge between motorsports and action sports,” Taublieb said.  After his short stay here this year, perhaps next year Stewart will come out on the winning end of a popularity contest.  In the debut of the skateboard Big Air Rail Jam final, Danny Way won gold on the mega ramp, which he created and brought to the X Games in 2004. Way, 35, of Encinitas, Calif., scored a 92.0 for a switch-stance 50-50 grind on the 28-foot rail while soaring over the ramp’s 50-foot gap. ... In BMX freestyle Big Air, Kevin Robinson of East Providence, R.I., won his third gold medal with a no-handed back flip over a 70-foot gap and a no-handed flair above the 27-foot quarterpipe. ... In the final event Friday, Kyle Loza of Trabuco Canyon, Calif., won his third straight gold medal in Moto X Best Trick, pulling the Electric Doom, a maneuver in which he performs a somersault over his motorcycle while holding the handlebars with one hand while soaring 30 feet from a ramp.  A version of this article appears in print on , on Page D5 of the New York edition with the headline: Oversize Talent, Unrivaled Personality. Order Reprints| Today's Paper|Subscribe
James Stewart, an X Games rookie who already has a reputation as the fastest rider on a motocross track, has been cultivating an image as a free-spirited showman.