For Winter X Games athletes, the inspiration can come from anywhere.

Snowboarder Danny Kass, who won the silver medal in slopestyle Saturday and repeated the feat in superpipe Monday, is constantly adding tricks to his repertoire.

"Sometimes I just think them up," he said. "And some of them come from watching other people."

There are only so many combinations of spins and flips, so snowboarders and freestyle skiers, at this point, are just adding or adjusting a standard set of tricks. They add their own style or attempt to go bigger than athletes who came first.

"I want all my tricks to be as big as my straight airs," said Kelly Clark, Olympic gold medalist and Winter X Games silver medalist in snowboard superpipe. "And I'm working on making them more technical, adding grabs to everything."

Ski and snowboard judges reward a trick executed with a grab because it increases the level of difficulty. The same is not true in all sports.

Motocross is going the other way. Instead of grabbing, the riders are releasing.

"When you feel comfortable with a trick, you take another part of your body off the bike," motocross rider Mike Metzger said. "That's how the sport evolves."

Monday, to win the best trick competition, Caleb Wyatt took both hands off the bars while throwing a back flip off the 90-foot ramp. It was only the fourth time he had tried to do it.

On his second run, Wyatt went one step further and tried to remove both hands and both feet on the flip. He lost control and crashed the landing. Stunned, he lay still for a moment and let the medics check him out.

Wyatt ultimately walked away uninjured, but it raises the question, especially after another rider was hospitalized Saturday: Why do athletes attempt tricks they haven't mastered in practice?

"Where I live in Oregon, the weather's kind of rainy and I don't have any place to practice," he said. "And most of these tricks are do or die anyway."

Athletes feel pressure to try new things in competition because any one trick's shelf life is so short.

At these Winter X Games, there was a will-he-or-won't-he anticipation about Metzger's back flip. It was exciting; it was new and not everyone could do it. The crowd loved it. But this year, any rider who didn't throw one was never really a contender.

And very soon, the snowboarders, skiers and motocrossers are going to have to step up and add even bigger tricks because a new breed of aerialist is moving in.

For the first time, the Winter X Games were host to a freestyle snowmobile jam. These riders, driving stock snowmobiles over towering ramps, take their inspiration from the BMX and motocross crowds.

"We got that first moto video, Crusty Demons of Dirt," said Kourtney Hungerford, of Bozeman, Mont. "We wanted to try it. Then we thought, well, our winters are longer than our summers, so let's see if we could do it on sleds."

It didn't take long before Hungerford and his friends were throwing standard motocross tricks: can cans, nacnacs and superman seat grabs while soaring through the air off snow-covered ramps.

Things progressed quickly to the point where three of the riders in Monday's jam session threw picture-perfect back flips.

And this is where motocrossers, skiers and snowboarders might need to watch out. The thrill of watching a guy flip a 250-pound motorbike loses some of its appeal when, a hundred yards away, other guys are flipping 450-pound sleds. Spinning skiers are even less exciting.

The snowmobile jam was merely an exhibition sport this time, but Winter X Games organizers are considering it as a full sport.

"The sky's the limit on what tricks we could do," Hungerford said. "It just depends on who has the guts to try it."

Soon, the traditional X athletes might be looking to these guys for inspiration.