ACCORDING TO PALMER'S mother, Jana, 57, a state office worker who lives in Coos Bay, Oregon, her son came out of the womb racing.

"He always had to be doing something fast: jumping, skiing, skateboarding," says Jana, a former figure skater who gave up her dream of the Ice Capades when she gave birth to Shaun at age 17. "I knew he was a rebel, because I was a rebel."

As a kid, Palmer lived in South Lake Tahoe, California, with his grandma, Perky, and his mother, who at the time worked as a blackjack dealer. His dad, Tim, left the family when Palmer was a baby, which made cash flow tight. When Palmer wanted a snowboard in seventh grade, he made one out of plywood, then added bindings crafted from bicycle tubes.

Known on the mountain as Mini Shred, Palmer would launch huge air, face-plant, come out cussing, then do it all over again. Impressed with his outsize talent, Sims Sports founder Tom Sims offered the 15-year-old Palmer a sponsorship. At 17, Palmer entered the 1985 Junior World Championships, in nearby Soda Springs. He swept the downhill, slalom, and halfpipe events. In 1989, at 21, he won his first world championship, in the halfpipe, at Breckenridge, Colorado. In 1990 he won again. The next few years were a blur of easy successes.

To stay fit in the off-season, Palmer started downhill mountain-bike racing in 1995. In July 1996, he won first place in the downhill at the NORBA national championships, at Big Bear Lake, California. A month later, he came in second at the 1996 World Cup, in France. He went on to win the dual-slalom world championships, in Australia, in September, which landed him a $300,000 annual contract with Specialized, making Palmer the highest-paid mountain biker in the world. For fun, he took up competitive motocross. In 1998, he made the finals of the Los Angeles Supercross.

At his peak, between 1997 and 2001, Palmer won six Winter X Games golds in four disciplines: boardercross, downhill biking, skiercross, and ultracross; owned a house in the Lake Tahoe area and a garage full of Cadillacs; and was pulling in $700,000 a year in prize money, sponsorships, and salary as CEO of Palmer USA Ltd., a snowboard-manufacturing business he started with Swiss investor Jorg Kunz in 1995. Palmer is still the CEO, but he refuses to talk about the business or his current financial situation: "I need to leave that blank right now," he says. "Let's just say it's not like it used to be." Today, he's primarily sponsored by Monster Energy. "I can't give you a dollar amount," says Scott Sepkovic, the sponsor's spokesperson, "but we like Shaun's persona and his story, especially this year, because he's killed it."

All those earlier years when Palmer was killing it in competition, he also lived in a bizarro parallel party universe. He guzzled pints of Crown Royal, trashed hotel rooms, smack-talked his competition, and occasionally brawled with his friends and enemies, all while taking the top podium spot in his signature gold-lamé suit.

"Shaun threw me across the room once because I got together with his girlfriend," says one of his best friends, Brad Holmes, 38, a pro skier and filmmaker currently working on a Palmer documentary called Palmer: The Miserable Champion. "Then he got together with my girlfriend." According to Jana Palmer, "Tahoe had a lot of drugs, and Shaun started at about age 15. But it went downhill when my mom died, in 1991. He hid away in drugs and alcohol, and I gained weight. I don't think we've been the same ever since."

"His mom was around, but if you ask Shaun," says Holmes, "he'd say his grandma raised him."

As Palmer tells me later, "I was pretty close with my grandmother when I was young."

Palmer's dark side caught up with him in May 2005: Depressed about a motocross sponsorship deal gone awry, he overdosed on cocaine and alcohol while partying with his buddies at Nevada's Lahontan Reservoir. He wound up taking his next joyride in a helicopter to intensive care.

"When I found him at the lake, he wasn't breathing," says his girlfriend, 28-year-old Niki Cerasoli, an artist from Los Angeles who met Palmer four years ago. "The doctors asked me if I'd be willing to take care of him if he had brain damage. It was the scariest day of my life."

After six days in intensive care, Palmer cut the drugs and booze cold turkey. By January 2006, he'd made that year's U.S. Olympic snowboard team. On Friday, January 13, he tore his Achilles tendon at a World Cup event, which took him out of competition for the rest of the season. Most everyone had started to write him off, but by 2007 Palmer was fully rehabilitated, placing second in a World Cup race in Austria.

I follow Palmer to Sun Valley, Idaho, in March 2008 to watch him compete in the last boardercross race in the Jeep King of the Mountain series. He's on his way to sweeping the event, which offers a $15,000 prize and a lease to a Jeep Liberty.

"Shaun transcends the sport," says Kipp Nelson, founder of 48 Straight, the umbrella event that encompasses the Jeep series. "He has a Bo Jackson ability to succeed at any sport he tries."

"I won't doubt that kid until he's off the face of the earth," says longtime pal and former Olympic speed skier Jimbo Morgan. "Shaun is the best athlete in the world, and he'll either burn it to the ground or win."