LAS VEGAS – Some people believe that, right now, a quiet revolution is taking place. In cities like London, San Francisco, Boston and New York, the ranks of bicycle riders are swelling with the rise of a new breed: the urban biker.

Traffic snarls, soaring gas prices and worries about global warming have prompted a big boost in cycling, affecting even places like Los Angeles – America's freeway capital – that have traditionally given bicycles the cold shoulder.

"What's really happened in the past year is a cultural shift," says Monica Howe, 31-year-old outreach coordinator for the Los Angeles County Bicycle Coalition.

At Interbike 2007, the bicycle industry's giant annual trade show, the shift toward the urban rider is loudly evident. Fancy road and mountain bikes are clearly no longer king of the roost – or road. It's the scads of fixed-gear, town, single-speed and other urban bicycles that are drawing the crowds.

The rise of the urban biker is reflected in Specialized's 2008 catalog, which lists 34 different models of city bike to choose from.

The company is even rolling out six different versions of its ultrapopular single-speed, fixed-gear Langster. Each model is named after a city that's on the urban biker radar: the four cities named above, plus Chicago and Seattle. The New York Langster has narrow handlebars for speeding through ranks of slow-moving cars, while the Seattle model is equipped with fenders.

"People really gravitated toward bikes with that urban feel," says Travis Widder, an associate production manager at Specialized. "We wanted to give nods toward cities where that bike sold well, where people really embraced that category."

Interbike 2007 is a lot less sporty than years past. Clothing manufacturers have more messenger bags on show. Jerseys and shorts are more urban, less multi-colored lycra.

Swobo, the trendy clothing maker, recently launched its first line of three city bikes, and is just one of several companies showing new urban rides.

If anyone gave birth to the urban biker movement, it's probably Sky Yaeger, Swobo's managing director.

Yaeger was responsible for designing a slew of bikes during her time as production manager at famed Italian manufacturer Bianchi. Some of her designs, like the fixed-gear Pista, have been elevated to cult status. Thanks to the bike's simplicity, it became the favored transport of urbanites like skaters and surfers.

"What happened is we crossed over the bike culture into skate, surf," she says. "The kids that are doing it now wouldn't have bought a bike five years ago. That's a huge delight to me – because they're on bikes."

In L.A., the bike revolution is helped by shops like the grassroots Bicycle Kitchen. "It makes it easy for anyone to put together a bike cheap," says Howe. "And it made it hip, which can't hurt."

Volunteers at the Salt Lake City Bicycle Collective, a nonprofit that provides tools and training for riders to maintain their bikes, have experienced a huge bump in visitors.

"It's gotten out of hand," says Michael Wise, the collective's treasurer. "We don't have enough volunteers to help the people coming in looking."

San Francisco's trendy Mission District is a hotbed of bicycle activity. A bicycle lane running the length of Valencia Street is a major artery, as hipsters in hoodies and precisely rolled, tight-fitting jeans flow along the street.

At Valencia Cyclery, which is often proclaimed the city's best bike store, sales associate Babs Brockaway says she's seen the number of customers leaving with shiny new fixed-gear ("fixie") and single-speed bikes skyrocket. The store stocks five or six choices, up from a single model two years ago. The simplicity appeals to neophyte riders overwhelmed by too much technology.

"It's simple: You just pedal," she says. "This is shocking, but there are people who buy bikes with gears, who don't shift gears."

Just across from Valencia Cyclery is Ritual Coffee Roasters, a popular coffeehouse often stuffed full of young hipsters glued to their MacBooks. It's also a favorite haunt of the urban biker.

Outside, Matt McDonald, a 24-year-old photographer from Boston, talks about his fixie.

"My friends in Boston were getting into these bikes, and it was just sort of appealing to me. It's like there's nothing to worry about, and they're just a blast to ride."