Clearly, the bicycle with helicopter blades shaped to look like angel wings was the opening-night hit at the Critical Mass Art Show. Lamentably, the idea still needs work.

Yes, a person can sit, pedal and rotate its wings, with a great flapping of feathers. No, one could not rise off the third floor of a Near West Side loft, at 1319 W. Lake St., in the middle room of a long, rambling exhibition space known as The Butcher Shop.

About 200 members of the bicycling community gathered Saturday night to mull the flights of fancy of two dozen artists working on bicycle themes. Along with cyclical drawings, sculptures, mobiles and videos, exhibits included a collage of recycled inner tubes and a bicycle with two front wheels, which powered a fan.

The purpose of the show, now in its third year, is to honor personal-powered transportation when the attention of the region is on the Chicago Auto Show, the nation's largest annual display of cars, now at McCormick Place.

Earlier in the day, many opening-night participants at the Critical Mass fest had ridden to the lakefront to distribute 1,000 fliers to car-show goers, warning of car-related dangers from pollutants to social isolation.

The latter, bicyclists suggested, can come from encasing oneself in a steel shell and moving through an environment without regard to the full panoply of its sights, sounds, smells and, among other thrills, the joy of fresh wind blowing in one's face.

"We are not anti-car," noted Eric Anderson, the show curator, taking a moment off. "We just want to celebrate the joy of biking and to share that feeling with others."

What Critical Mass would like to see, he added, is a policy of "appropriate use" for cars. That means "when no other means of transportation is practical," though, as one cyclist noted, "any place on Earth is within biking range, if you have the time."

"What exactly," wondered a visitor during an evening that included a buffet of fresh vegetables and dancing to canned music, "is Critical Mass?"

The idea grew out of an observation by urbanologists studying traffic patterns in cities in China. With no signals to halt cars, bicyclists at crosswalks, they noted, would clump together into a human shield. When the shield grew large enough, a point described as "critical mass," it would move into a street, stopping cars so riders could cross.

Similarly, in San Francisco, in August 1992, a loose gathering of bicycle commuters began taking to the streets on a regular basis to ride home together. The idea, which now has taken hold in 150 cities around the world, spread to Chicago in fall 1997.

Now, riders gather at 5:30 p.m. on the last Friday of each month at Daley Plaza near the Picasso statue. They vote on a route. Then they go through snow, rain, cold, gloom of night, or rush-hour traffic. Last month, for example, the destination was the Baby Doll Polka Club, at 6102 S. Central Ave., near Midway Airport. Many stayed until 1 a.m., then biked home.

Sometimes, the group stops, everyone dismounts and holds their bikes over their heads, a gesture known as a "Chicago Holdup." The group's Web site (www.chicagocriticalmass.org) notes in its frequently asked questions section that this is a "symbolic gesture to emphasize our belief that bikes are superior to cars as a form of urban transportation."

"You see architecture. You see the mosaic of city life. You're right in the scene, not riding by in an enclosed capsule," mused Gareth Newfield, a writer of computer software who often rides his bicycle to jobs, on routes from 3 to 16 miles.

Many of the offerings at the art show, which runs through Feb. 26, seemed aimed at specific clienteles. One, for bird-owners, combined a bicycle with a cage big enough to hold a parrot. Another, for musicians, used pedal power to activate sticks and bang a drum mounted behind the rider.

For many, the night was a chance to exchange tips toward creating "a community with cleaner air, quieter streets and fewer parking garages," as a Critical Mass brochure put it.

"I'm not afraid of winter anymore," said Julie Dworkin, an advocate for the homeless who now rides 7 miles each way from her home in Logan Square to an office in the South Loop.

She wears a helmet, a fleece face mask, thermal bike tights, long underwear, a jacket, rain pants, gloves and "bootie covers" over her boots to keep warm, she said.

Many noted, with approval, plans by the city's First Bicyclist, Mayor Richard Daley, who frequently uses a bicycle at his summer home in Michigan, for a coast-to-coast ride to raise funds for charity. On the other hand, noted Michael Burton, while hanging a pro-bike mobile, it would also "be nice to see him ride to work, through the streets of his own city."