THE NEXT MORNING in Louisville, my phone rings at 8:15. It's Astephen. "I'm headed over to the venue now," he says. "Travis is walking the course."

An hour later, I'm drafting behind an energetic Astephen as he heads toward Pastrana's trailer. The star appears—his racing suit pulled down to his waist, exposing an upper body utterly devoid of fat—and heads our way, taking the pained steps of an arthritic old man.

"Dude, you know where the medical staff is?" asks Pastrana. "I banged my knee, and it's all swollen up."

They head over to the on-site doctor, who diagnoses Pastrana's injury—an angry bubble colored red, blue, purple, and yellow—as a swollen bursa, the fluid sac between the knee and lower leg. "It might be painful, but you'll be OK," he says. "It's not essential to movement."

"OK," Pastrana says as he suits up. "It just feels weird. I think I'll practice."

Astephen pulls him aside. "Get some good practice in today, but take it easy in the prelims. Just get into the finals—there's no need to go nuts."

Astephen's phone rings. It's Mirra, on his way to a taping for a local morning show at the House of Dew, a temporary prefab Colonial. By the time we arrive, Mirra's getting some last-minute makeup, but Astephen doesn't like the look of the loose, flat-brimmed ball cap sitting atop his client's shaved head. He tells him to lose it.

"As Eddie Vedder says," Mirra answers, "it's not how you look; it's how you feel." The hat stays on.

But how long can you feel this good? Mirra's been a pro for 12 years—a lifetime in action sports. Later I ask Astephen if he's thinking about Mirra's eventual retirement.

"In my heart, he's got five more years; in his, he's got three," he says. "But who knows the answer?"

"Who knows?" is the question that will define Astephen's and his clients' futures. Do action-sports stars have a pop-culture afterlife? If you look at their side jobs, it seems that they do.

Travis Pastrana recently signed with Subaru to race rally cars. Bob Burnquist has a film-production company. Carey Hart's focus is his tattoo shop and show.

"A lot of my guys are a long way from retiring full-time," Astephen says. "But when they do, they'll be fine."

Meanwhile, Astephen's role grows—or, rather, mutates. After Astephen sold his company to WMG—a burgeoning conglomerate owned by Casey Wasserman, 31, the deep-pocketed grandson of former Universal Pictures chief Lew Wasserman—he started integrating his stars with WMG's various other pursuits to produce projects like Pastrana's latest DVD, Nitro Circus 3. With the new capital, Astephen recently opened a London office to start building a European motorsports division.

"Everything's growing," he says, "and I'm addicted to it."