Skiers, bikers and snowshoers set out Saturday on a 200-mile race into the wilderness that organizers and participants are calling "the toughest and most unique winter ultra-marathon in the world."

Sixty entrants gathered in a warm Humana Hospital conference room Friday to get medical warnings about frostbite and other hazards and for a briefing about trail conditions north of Anchorage and rules of the unique race.Just before Saturday's start, racers had to declare their mode of transportation or, as race director Dan Bull put it, "Choose your weapon" - bicycle, skis or snowshoes."It's billed as the toughest thing around. That's why I'm doing it," said Simon Gibson, 21, who made his first trip to the United States from his home in Sheffield, England, where he trained in rain-soaked mud to prepare himself for riding a bicycle across 200 miles of snow.

"If you can do this, you can do anything," Gibson said.

"It's a challenge," said Donald Bliere, 27, of Montreal, who also plans to pedal across the snow-covered back country.

"It's an adventure," said Binget Hanson, 24, who works as a bike messenger on the streets of Seattle. She even recruited her father, a doctor in Alaska, to volunteer to staff one of the checkpoints, along with other medical personnel, to make sure racers are OK.

"It's a unique experience," said Cliff Caton, 39, a commercial loan officer at a Kansas City bank, making his first trip to Alaska for his first bike race in the snow. "My employer thought I was nuts, and I'm beginning to wonder myself."

Not everyone finds the experience that strange. Mike Luedke, 24, a forklift operator, said he rides his bike all winter in Anchorage.

The race has been dubbed Iditasport, after the 1,150-mile Anchorage-to-Nome Iditarod Sled Dog Race held every March. Iditasport goes along part of the Iditarod Trail.

The $30,000 race purse offers prizes in gold to the winner in each category of travel, plus the overall top Iditasport finishers.

Racers must bring an arctic sleeping bag, food and a stove - to melt snow to make water - and be self-sufficient along a trail through woods, over frozen lakes, some unfrozen creeks and up and down hills.

Snowshoers have to cover only 100 miles of the trail, but bikers and skiers must travel 200 miles.