From the top of Kilauea Avenue, the road plunges like a roller-coaster drop. Drivers ride their brakes and pedestrians ride their heels to navigate the descent. But not Matt Ching, who hopped onto his fixed-gear bicycle the other day and put his faith in his legs.

He was "bombing Kilauea."

Halfway down the hill, at the intersection of 18th Avenue, a group of Ching's friends was caught off guard by his spontaneity. One of them ran toward the intersection, frantically waving his arms to stop traffic cutting across Ching's path. The last time Ching did this, his chain flew off and his rear tire blew out when he tried to slow it with his foot.

But he was bombing faster now.

Bicycles like this have no brakes, their users relying instead on leg strength to stop. When the rear wheel rolls on a fixed-gear bike, the rider's legs move, too, never resting. Push forward and go. Push back and hope it's enough pressure to brake in time to avoid a crash.

In the last two years, the fixed-gear riders have multiplied on the streets of Honolulu, attracting riders who flaunt convention — and safety — with a fearless approach that's similar to urban skateboarding.

As Ching accelerated down Kilauea, wearing a green ball cap instead of a helmet, he checked his speed with his legs.

He occasionally locked the rear wheel of his lime-green bike and slid sideways to slow himself with a dicey maneuver called skidding. He was still moving fast, though, passing traffic as he hit the intersection of common sense and reckless abandon.

His friends howled with delight. Someone on Kilauea honked a horn.

"I'm just having fun," said Ching, a 24-year-old importer/ exporter of Japanese health products who fell in love with the intensity of fixed-gear bicycles. "I kind of want to do it again."

RACING ORIGIN

Fixed-gear bicycles, or "fixies," are not new to the cycling world. They have their origins in track racing, in which riders zoom around banked ovals made of polished wood or concrete. Their use changed in the 1980s when they became the ride of choice among bike messengers in San Francisco, Portland, Ore., and Seattle, as well as in Honolulu, said Gary Gavin, general manager of The Bike Shop.

The bikes are a sprinter's statement on simplicity. They are built to go fast, with nothing crafted into their design to slow or even stop them. Newcomers sometimes add brakes, but fixies are a passion that demands brute force.

"There is no coasting," Gavin said. "If you are going downhill, you have to be able to hold back your speed with your legs. You are sort of fighting it."

Stopping requires a rider to plan ahead, although quick reflexes are a bonus. John Hamilton, who admits he has run his share of red lights, eagerly rides through bumper-to-bumper traffic but always keeps an eye open for a gap between vehicles that will let him dart out of danger.

"Sometimes you have to go into the other lane, and that's kind of scary," he said. "But if it's the back of someone's SUV or the other lane, the other lane looks pretty good."

Hamilton could add brakes, but that "takes away half the fun," he said.

A 21-year-old English major at the University of Hawai'i-Manoa, Hamilton started riding fixed-gear bicycles two years ago. He pulled his first bike out of a trash can and rebuilt it. It was a 1970 Schwinn Varsity — "a tank," Hamilton said.

"I think that's how we all started," he said. "But once you get the taste of it, that's when you start spending a large amount of money."

Hamilton has spent about $1,200 on his current ride, a red, sleek bike with a hard leather seat and narrow handlebars to help him slip between lines of traffic. He rolls on aluminum rims — one white, one red — and tires pumped up to 120 psi.

"You can create a bike that reflects you as a person," he said. "That's one of the cool things."

LEARNING TO SKID

The lack of traditional brakes — and moves like the one Hamilton uses to get through traffic — have given nonriders the impression that fixed-gear bicycles are a one-way ticket to the emergency room. Not so, said Travis Horikawa, a 30-year-old musician and former mountain biker from Wahiawa.

"The misconception the public has is these are bikes without brakes," he said. "But once you learn skidding, they are perfectly safe."

Skidding is a weight-shifting trick. "It's kind of taking the weight off of your rear wheel and locking your legs so your rear wheel freezes and you stop," he said. "It's not that hard to learn."

Fixed-gear bicycling evolved when riders started doing tricks, like pedaling backward in circles, sitting on their handlebars or riding while balanced on their rear wheel and spinning their front wheel. They'll ride down stairs, bank against a wall and slide up, over and along obstacles.

A trip across town can include a little of everything, something that Ryan Lau found instantly exciting.

Lau, a 27-year-old backstock coordinator for American Apparel from Kahalu'u, had been an avid skateboarder for 12 years. But when he lived in San Francisco in 2004, he needed better transportation and turned to the fixed-gear bikes he saw all over the city.

He found their style of riding meshed well with his skating past. "It let me have both," he said. "The tricks of skateboarding and the ability to get around."

Not every trip was pleasant, though. Lau once flew so fast down a hill in San Francisco that he lost control on a turn and went through the windshield of a parked car.

"There was glass in my face and my bike was folded," he said.

Lau won't wear a helmet, though. "I like to think I have enough control that I don't need it," he said. "They just seem like they get in the way."

Lau, who created a Web site to promote fixies in Hawai'i — www.alohafixed.com — said he and his friends have caught flack about their safety habits from traditional cyclists. They've also been called posers because they'll ride in T-shirts and skinny jeans instead of Lycra.

No matter.

"Some people get insulted by the fact that you're using a racing bike," Lau said. "We just want to go out and ride."