Don't worry - she can stop. By bracing against the momentum of the pedals, she glides along an East Burnside Street sidewalk to a halt at Nocturnal, where Riddle is attending a concert.

She whips out a small U-lock and attaches her bicycle to the rack in front of the club. Next to it is another bike. Also one gear and no brakes. Same with the bike around the corner.

What's going on? Have bike commuters across the city given each other a gigantic dare? Have gear shifters become too expensive?

What has happened is that Portland's tastes for fitness, counterculture and simplicity have all melded into one thing, and it is called the fixed-gear bicycle.

Propelled by its pedals and only by its pedals (it can't coast), the fixed gear, in the age of the high-tech mountain bike, has come to be seen by many as a monument to the original idea of the bicycle.

Exempt from the extra chain rings, derailleurs, cable and tubing necessary to change gears, its form is a clean, simple icon.

"I feel it's about bravado and style for a lot of people," says Molly Cameron, whose bike store, Veloshop, attributes nearly half of its business to fixed-gear bikes. "But people get really passionate about it. The fixed bike is more a part of you than anything else."

Mark Ontiveros, co-owner of River City Bicycles, says the store's sales of fixed-gear bikes have skyrocketed in the last year or so. Sensing the trend, Ontiveros says the store bought 100 Specialized fixed-gear bikes and has sold almost all of them for $550 each.

Ontiveros, who is in his late 40s, represents the other side of fixed-gear popularity, which is that they just make sense, especially in wet, gritty Portland winters. Their simplicity gives commuters fewer parts to maintain and replace.

The city has seen the organization of weekly fixed-gear rides, an annual one-speed festival, a fixed-gear category at local races and even a few Web 'zines devoted to fixed gears.

With physical, aesthetic and social appeal, they have brought together kindred spirits looking for a different way to pedal.

"You have the older people who do it for fitness and the younger people who do it for coolness," says David Auker, an ex-racer who now commutes on a fixed gear.

The fixed gear was one of the first bicycles invented. Early racers rode them at tracks known as velodromes to the delight of spectators 100 years ago.

Few velodromes remain in the United States - one is the Alpenrose track in Southwest Portland - but cyclists have taken fixed gears off the track and into contemporary urban America.

Their recent popularity has been one of rediscovery, for racers, bike messengers and commuters.

Auker, 55, says he got his first fixed-gear bike as a road racer in the early 1970s. It was standard for racers to practice in the winter on a fixed gear, since it worked you harder over a shorter amount of time and there was little grit to clean up after a ride.

But Auker began to ride his fixed gear in all seasons, seeing its virtue in commuting around Portland. He liked that it wasn't about speed but balance and control.

He liked that you could pedal back and forth at red lights and then blast off ahead of the cars when the light turned green.

"It's like a sports car, having a nice tight gear box," Auker says. "The Portland urban area is a paradise for riding a fixed gear."

Now, fixed gears are so ubiquitous among Portland's punk rock hipster culture that bike mechanic Doug Moak describes what he calls a "blueprint" for a fixed-gear bike and a "uniform" for many of those riding them.

Old European lugged (jointed) frames are usually accompanied by a track handlebar angled downward, and they are ridden by people in cut-offs, a T-shirt, a bike cap with bent brim, and small U-lock in the back pocket.

"A lot of the New York City messenger culture has come here," says Moak, who has ridden a fixed gear for about 10 years. "In my opinion, there is a messenger fashion here."

But while Portland's fixed-gear culture may have been imported from bigger cities with larger bike messenger scenes, such as New York, Chicago and San Francisco, Portland's version has taken on meaning of its own.

With the fixed gear, the city seems to have found a hallmark for its bike friendliness, extreme hipness and even its resourcefulness.

"I like the culture here," says Ross Allan, who was a bike messenger in his native London for seven years. "It's about making do and mending. It's about renovating. There's a real respect for old quality bicycles."

As such, many Rose City fixed gear aficionados expect the objects of their affection to maintain their popularity.

Bike shop owner Cameron, who had to dig for information about track bikes a decade ago, says she is vested in them not as a fad or a secret club, but as an essence of bicycling she wants everyone to experience.

"I'm trying to demystify it. It doesn't have to be for the elite," Cameron says. "The more people on fixed gears the better."

(Copyright 2005 by The Associated Press. All Rights Reserved.)