Fixed-gear culture is about style, danger, simplicity, resistance to authority, commerce and more.

Most of that was reflected in the shirt Sage Bauers was wearing while working at Bicycle Business on Freeport Boulevard.

The shirt had the cut riders like and a design that echoed the simplicity of bicycles that have only one gear. It said simply, "Ride Fixed Gear Go to Jail," appended with a section of the Oregon vehicle code.

That's the section that says bikes must have brakes.

So-called "fixie" bikes often don't. (We'll come back to this point later.)

What they do have is handlebars, a frame, two wheels and a set of pedals and crank arms to drive the rear wheel. To stop, the rider stops the cranks from turning.

Fixed-gear bikes also have cachet.

"It's going up and up and up and up," said Bauers, speaking of fixed-gear sales.

A few years ago, Bicycle Business was the domain of serious road bikers who bought frames and components appropriate for the Tour de France, Amgen Tour of California or Giro d'Italia.

Now, business is dominated – about 80 percent, Bauer said – by track-style bikes and the trappings of the fixed-gear culture.

In short, it's gone from Giro to fixie in nothing flat.

Low-budget riders who don't buy a $2,000 track bike (the granddad of fixies) might opt for an old Fuji, Schwinn or Nishiki frame and trick it out with fancy, often neon-bright, wheels.

Those old frames have doubled in value as a result, Bauers said.

Bicycle Business may be the commercial hub, but fixie aficionados – almost all in their teens and 20s – are everywhere in midtown and surrounding areas.

On Tuesday nights, they can often be found at Rubicon Brewing Company. Tuesday, not entirely by coincidence, is cheap beer night.

You'll spot fixies locked to racks and poles everywhere, but in especially large numbers at City College.

If you hunt, you can find fixed-gear riders at an alley cat – an informal nocturnal race – or playing bicycle polo. (Bike polo players are keeping their location secret because the players were chased from their old locale under the W-X freeway after a previous news story.)

Earlier this month, hundreds of fixed-gear riders converged on the Crest Theatre for the Sacramento premiere of "Macaframa." Bikes were locked to every conceivable stable element on K Street, including the Light Rail boarding platform. Every passing train threatened to obliterate one locked bike, clearing it by mere inches.

"Macaframa" is a beautiful movie, kind of an "Endless Summer" for the fixed-gear set and a love song to San Francisco, where most of it was filmed. (See clips at www.macaframaproductions.com.)

It is also the kind of thing a parent doesn't want a 12-year-old boy to see. There is no bad language; no sex; no guns, bombs or knives – just lots of screaming down hills and zooming through stop signs and red lights without benefit of the aforementioned brakes.

"Knock on wood, I haven't known anyone to get seriously injured," said Colby Elrick, a rider and one of the filmmakers.

What about the guy in the film who bombs around a corner and hooks his bike on the bumper of a parked car, sending him hurling over the handlebars?

He broke his toe, Elrick said. "He was fine."

While Elrick said San Francisco police don't bother, he said Sacramento police have threatened him with a citation for not having hand brakes on his fixed-gear.

The California Vehicle Code says a bike on the roadway has to have a brake that will cause the bike to skid on clean, dry, level pavement.

"We just follow the laws," said Officer Konrad Von Schoech, a spokesman for the Sacramento Police Department. "It's the law. You have to have brakes."

"They do have brakes," said Sacramento rider John Cardiel. "They're in their legs."

Bikers stop the pedals to skid to a stop. There is a wide variety of trick skids, and riders going downhill can "whip skid" – a fishtailing motion – to slow down.

Cardiel is a near-legendary professional skateboarder from Sacramento. Or was, until a van hit him.

He has some use of his legs, but can't skate anymore. So he rides a fixed-gear bike.

"I took up bicycle as a second (an alternative) to a wheelchair," he said. "I need to move."

He drew cheers for his appearance in "Macaframa," riding along one of the river trails.

Despite the enthusiasm, yelling and spilled Pabst Blue Ribbon in a nearly full Crest Theatre, filmmaker Elrick termed the Sacramento screening "boring." He and his co-director, Colin Arlen, who grew up in Roseville, described audiences in San Francisco and Los Angeles as more energized.

San Francisco riding is more extreme, as well, Elrick said. It's because of the hilly geography.

"You'll die," he said, "if you don't know what you're doing."

Sacramento is more laid-back, but fixed-gear riders are getting a reputation for going through traffic lights .

That worries John Boyer, who runs the Bicycle Kitchen, a self-repair bike co-op on I Street.

"The new generation has a good eye for simplicity," he said, referring to the trend that admires fixed-gear – a bike stripped to its essentials. "But there are a lot of downsides to riding fixed-gear."

Damaged knees from pushing high gears and the tendency to run lights are among them, he said.

Those injuries and risks are "not in the lexicon of the 17-year-old," Boyer said.

He's concerned that a few traffic disasters will turn back the clock on the advances – more commuters and better bike lanes – that cyclists have made over the years.

"All the gains we've made can be lost."