Erich Schlegel / The New York TimesColten Moore takes part in a freestyle aerial exhibition at the ATV Pro Challenge event in Kemp, Texas, in October. The event was a memorial to his brother, Caleb Moore, who died in competition during the X Games last year.

KEMP, Texas — The life of an all-terrain vehicle racer is a peripatetic one, big on low-budget adventures but small when it comes to paychecks. The best racers in the nation were here in October for the ATV Pro Challenge in Memory of Caleb Moore, which offered $30,000 in total prize money, a record for the sport.

Caleb Moore showed up on this circuit as a teenager and hooked up with a team based in Georgia and competed throughout the South.

“He’d show up by himself in a beat-up truck after driving all night,” said the team’s owner, Jorge Cuartas. “And he’d tear it up at races. Then we’d share a room and do what’s called bench racing, reliving the day’s races. It’s all we could afford.”

But what Moore liked to do more than anything else was make his machine fly. He had more than nerve. He possessed the discipline to break down and think through tricks.

“I’d watch him work through a routine, and sometimes, it looked like nothing was happening,” Cuartas said.

“He’d let go of a hand here and do twist there — subtle stuff just to get a feel. But then a few hours or a few days later, he would look like an artist soaring up there. He was wired different than most people,” Cuartas added.

Never far behind him was his younger brother Colten.

“I can pretty much say he taught me everything I know,” Colten Moore said. “When we raced together, he pushed me to go faster and made me jump jumps that I wouldn’t have done. Even if I couldn’t do it, he would push me until I could.”

Their mother, Michele, and her husband, Wade, were not wild about the boys’ burgeoning passion for freestyle, the practice of hurtling machines off a ramp. Wade Moore did not mind the racing or the thousands of dollars to keep them on the road.

“Then they started doing this trick stuff, at the track over big jumps,” Wade Moore said, “and they started asking about it, and I kept saying: ‘No, no. You ain’t doing it.’ ”

Finally, however, he gave in. Soon, his sons were barnstorming throughout the Southwest and Mexico. Early on, Caleb was booked into a show in Montreal by promising that he could do a back flip. He had never tried one and had just four weeks to learn. The brothers drove to Michigan, where a friend had a ramp and a foam pit.

It took a couple of weeks, but Caleb called home one day and told his father he had perfected the back flip. Wade Moore, however, wanted to see for himself and met his sons in Montreal.

“I pulled his younger brother to the side because I’m freaking out,” he said. “I got into his face and I’m like: Tell me! Does he have it?”

Colten assured him Caleb did. When Wade Moore saw Caleb loop through the air, he was stunned.

“It was the most exciting moment of my life,” Wade Moore said, “and the most stressful, heart-pounding moment of my life.”

Fear Factor

The X Games have capitalized on the fear factor that rides shotgun alongside the gravity-defying stunts of skateboarders and snowboarders as well as motocross and snowmobile drivers.

In 2007, the Mega Ramp was unveiled for skateboarders in the Summer X Games. It was met with awe as well as shudders after Jake Brown fell five stories and was knocked unconscious. In 2009, after winning X Games gold, Jeremy Lusk, a freestyle motocross star, crashed on a jump in Costa Rica, suffering a fatal head injury.

On New Year’s Eve 2009 in Utah, Kevin Pearce struck his head on the halfpipe and was critically injured, ending his snowboarding career. Two years later, Canadian freestyle skier Sarah Burke took a nasty fall on the same pipe. Ten days later, she was dead.

Last year’s Winter X Games in Aspen, Colo., however, not only were harrowing for extreme athletes but also cast their pursuits in the most unflattering light. At least six athletes left the mountain in ambulances.

The freestyle snowmobiling competition began with eight participants and ended with four, including the winner, Levi LaVallee.

“I know my sport is dangerous,” said LaVallee, who captured his sixth X Games gold medal after missing the previous two years because of a broken pelvis and broken leg suffered in training jumps, “but it was clear there were some things that needed to be addressed to make it safer or we weren’t going to be part of the X Games as a sport.”

Tweaks for Safety

The Winter X Games in Aspen this week will include a snowmobile freestyle competition, but one that ESPN officials say will be significantly safer. Among the changes are required body armor and helmet padding, and spring-loaded skis to prevent the tips from sticking in the snow.

“The reality with all these events is that we continually evaluate safety,” said Scott Guglielmino, ESPN’s senior vice president for programming and the X Games. “We work with safety experts, course designers and our athletes to try to mitigate as much risk as we can. Risk is prevalent, but these are world-class athletes, and if the X Games didn’t exist, they’d still be competing somewhere and participating in something they love.”

For LaVallee, numerous concussions, three cracked vertebrae, broken ribs and tibia, and collapsed lungs have been the cost of doing business. He will miss the snowmobile freestyle after aggravating a muscle tear he suffered last year at the X Games, but LaVallee will compete in the snocross and the long jump. At 31, he also recognizes it is harder for him to bounce back from injuries.

“I’ve not only had a career, but I got a future because of the sled,” he said. “With my team, I have a business to walk into when I’m finished. I won’t have to go find a job.”

Back Flip of a Lifetime

By 2009, the Moore brothers could do almost any stunt atop an ATV and could reach dizzying heights. Wade Moore had built his sons a ramp and foam pit outside the family home in Krum, Texas. But Caleb and Colten were still living show to show and hardly felt like pros. They needed to go where the money was and discovered where that was while watching the 2009 Winter X Games.

They were doing complicated tricks on their ATVs; why couldn’t they translate them to a snowmobile? By December, they talked Polaris into sending a couple of sleds to them in Texas.

They tried them in their foam pit and found the sleds far easier to flip than their quads. The Moores shot a video of the tricks they could do in the air and sent them to Joe Duncan, who coordinates the sled competitions for the X Games. Then they went back to Michigan, this time to learn how to actually ride in the snow.

Less than 30 days later, they were competing in the 2010 X Games.

When the Moores returned to the X Games, Caleb took the bronze medal in freestyle and the silver in best trick, but an impromptu stunt initiated by Colten elevated the brothers to crowd pleasers as well as snowmobilers. Colten put Caleb in the driver’s seat of the sled and hopped on the back. They zoomed toward the ramp.

They did a back flip with Colten adding a handstand off the back for emphasis. They landed softly as an ovation erupted, and the video of the two looping through the air as one has become a signature highlight for the Winter X Games.

Last year in Aspen, on the opening day of the games, the brothers conceded that that single unscripted moment had eclipsed everything either of them had accomplished on a sled.

This was their fourth X Games, and the Moores were no longer curiosities from Texas but favorites to win.

That night, Caleb was up first. Their parents and a couple dozen friends and relatives were on the mountain when he underrotated on a back flip and caught his snowmobile’s front skis on the top of a landing ramp, vaulting him facedown into the snow. The sled, weighing nearly 500 pounds, bounced on top of him and knocked him unconscious.

Wade Moore was at Caleb’s side when he came to. Wade walked Caleb to the medical tent with what was initially called a concussion. Michele Moore accompanied Caleb to Aspen Valley Hospital.

Thirty minutes later on the same ramp, Colten, too, missed his mark and was catapulted off his snowmobile. He was strapped onto a gurney and taken by ambulance to join his brother.

Colten, with a separated pelvis, was released the next day. Caleb, however, was in trouble and had been flown to a hospital in Grand Junction, Colo. He never really regained consciousness. One week later, Caleb Moore died of internal injuries. He was 25.

A Muddy Memorial

Eight months later in Kemp, Texas, the Moores made camp in a muddy parking lot. Before them, dirt was groomed into mounds and switchbacks that sent four-wheel motorcycles arcing into the sky. Colten, 24, was going to give a freestyle demonstration on his ATV.

Thousands gathered here at a memorial for Caleb Moore, a race organized by riders he grew up competing against on dirt tracks hollowed out of woods throughout the South. It was as much a rally as a fundraiser, a bittersweet celebration of one of their own who had scaled the heights of action sports only to become the first fatality in the X Games.

Wade Moore said there was little doubt Colten would continue riding. Within months of his brother’s death, Colten was back on a national tour with the Nuclear Cowboyz, a sort of dirt bike and ATV arena opera. He also circled the globe as part of Travis Pastrana’s Nitro Circus Live, the “action sports collective” featuring Pastrana and his friends doing aerial stunts on every machine imaginable.

Said Colten to his father: “It makes me feel closer to my brother.”