Rick Hill found his muse in a milkshake full of bugs.

And the muse, which in another time might have merely turned a person's stomach, eventually rewarded him with some fantastic PR.

As head of Metropolitan Choppers LLC, a small custom-motorcycle shop in Frederick, Md., Hill already had discovered folks would pay $55,000 or more for choppers tailored to their whims and fantasies.

Then came an inspiration: Hill would pay homage to his favorite TV show in chrome, rubber and steel. He told his crew to build a chopper worthy of "Fear Factor," the reality show that somehow finds contestants to swim with alligators, dive into sewage or drink a worm-and-cockroach milkshake.

"Everybody said, 'Oooh, that's a gross show,' " Hill said. "And I said, 'Great, we have a lot to work with.' "

After a few calls to Hollywood, Hill's small company was supplying choppers as prizes on "Fear Factor." And it happened just as the national craze for motorcycles, particularly customized choppers, was gaining speed.

"It's really become this kind of cool thing to do, to have this custom-made chopper," said Mitch Boehm, editor of Motorcyclist, the nation's oldest motorcycle magazine. "It's the look, it's T-shirts, it's toys, it's art, it's everything. The whole chopper phenomenon is just massive. It's really part of Americana."

Choppers were what happened when a bunch of World War II vets returned home and started tinkering in their garages. Like blue-collar artists searching for their souls in the Industrial Age, they took factory-made motorcycles, chopped them up and made machines of their own.

By 1969, when the movie "Easy Rider" showed Peter Fonda and Dennis Hopper cruising on a pair of motorcycles in a doomed search for freedom, the chopper had become the symbol of cool.

There are no numbers on how many customized chopper companies there are in the United States because they do not report data to the Motorcycle Industry Council, according to Ty van Hooydonk, a spokesman for the council's media resource center, known as Discover Today's Motorcycling. But a million motorcycles were sold last year, and about 33 percent were "cruisers," or factory-made motorcycles that have adopted traces of the chopper style, Van Hooydonk said.

Van Hooydonk said the classic chopper is usually one with gas tanks sleek as teardrops, sky-high handlebars and bobtail fenders, which are cut short and straight to reveal most of the rear wheel. Most important is the upward thrust of the frame and the long, raked front forks: The front suspension is lengthened and angled forward so that the front wheel sticks way out.

Two things have pushed the chopper into the mainstream.

Harley-Davidson Inc.'s resurrection fed an interest among baby boomers. But once every yuppie had a Harley, bikers wanted something else, Boehm said.

Then, starting in 2002, came "American Chopper," which takes viewers inside a custom motorcycle shop.

"There are literally hundreds and hundreds of these companies around the county," Boehm said.

One was Hill's. One night, he was watching "American Chopper" with his 13-year-old son, and it was like a spark plug firing: Why not build a bike like that?

Their first creation was the Torch Bike, featuring a real oxyacetylene torch affixed to the gas tank. (The torch is not, of course, functional.) The chopper won the top prize in a local auto show, which delighted visitors but annoyed several car exhibitors.

"We knew we were on to something," Hill said.

Soon they had customers. The founder of the 84 Lumber Co., Joseph A. Hardy III, got a chopper styled in woodgrain with a seat that looks like a tool belt.

Professional golfer John "the Lion" Daly rolled out of the shop with a fully raked chopper with an ostrich-skin seat (to match his shoes), golf ball-like hubcaps on the rear wheel and a Dunlop golf bag on the back. The chrome front wheel shows Daly's motto: "GRIP IT & RIP IT."

But Hill's favorite is his "Fear Factor" bike. It has a terrarium of fake worms tucked under the seat, a working blender attached to the frame and a "chuck bucket" dangling, appropriately enough, from the bike's sissy bar.

"When people see our bikes, they go all the way around it, and they're child-like. They don't want to miss anything," Hill says. "These are pieces of art."

A Metropolitan Chopper begins by identifying possible themes. Hill toured an 84 Lumber store to come up with the design for Hardy's bike.

The design then goes into the shop, which is ruled by Dan Kessinger.

Kessinger stands 6 feet 4 and weighs 400 pounds. He is known as "Big Dan." He shaves his head, wears a hoop in each ear, and lets his beard grow like a patch of rusty steel wool. His arms are wreathed in tattoos. He looks like Mr. Clean, if Mr. Clean were to trade in his white duds for black and became a biker.

Paul Fuhrmann, 25, disappears behind a welder's mask, and his high-voltage torch snaps to life, bathing the workshop in an extraterrestrial glow that could sear a person's retinas.

A few feet away, Brad Rhinecker, 21, whips out a grinder. A plume of sparks bursts from the machine.

Kessinger said the bikes they are working on will belong to G. Gordon Liddy, the former Nixon operative who is now a talk radio host. Liddy told the crew he wanted a Battle of Britain theme. Nothing about Watergate. Kessinger wants to keep the details of the bikes under wraps until delivery.

Hill won't say how much his company does in annual sales. But the bikes sell for $45,000 to $100,000, and the crew builds about one a month, he said.

"This really is a hobby — a hobby on steroids," Hill said.