By Bobby Feingold

On a frigid winter night, black-clad bikers gathered in the center of Copley Square. Straddling their bicycles, the group of more than 15 circled around their informal leader in preparation for their ride. Shalom Keller, a grizzled-looking character with a chin of strawberry blonde scruff and scraggly hair, climbed onto a stone fountain ledge to address the group. Each rider leaned in, preparing to listen attentively, anticipating what he would say. But perhaps due to the 20-degree weather that Feb. 24 brings in Boston, the desire to rabble-rouse petered out somewhere between his brain and mouth. “Yadda yadda call for solidarity,” he said sarcastically.

That night, Keller was acting as the unofficial leader of the monthly bike ride, known as Critical Mass.

Held on the final Friday of each month, the rides are part of a national network that began in San Francisco in 1992.

They are designed as a way for fellow bicycle enthusiasts to meet up and make their presence known to their automotive counterparts.

When the weather is nicer, Keller said the ride would likely draw more than 100 people on the route from Dartmouth Street to Memorial Drive along the Charles, and down Massachusetts Avenue to Harvard Square.

Throughout the ride, chants of “Whose streets? Our streets!” sprang up, giving the whole affair the feel of a protest.

“It’s just the hardcore ones tonight,” Keller said of the lower turnout. “It’s ‘effin cold out!”

The group calls itself an “unorganized coincidence” on its unofficial Web site (nothing in the group is official). Originally, the intention was to promote bicycle safety and an environmentally friendly mode of transportation, but the movement has grown exponentially worldwide.

Jesse Jolly, a middler human services major, said she hoped cars took notice.

“With eight million cars here, people don’t notice the bike riders,” Jolly said.

Now, there are rides that take place in Australia, Canada and many locations in between.

“We bikers have little control of the roads,” said Peter Bailey, a junior computer science and cognitive psychology major. “The roads in Boston were not made for riders.”

They’ve even coined their own form of government – a Xerocracy. The idea is that word spreads about the rides through other bikers, rather than more central forms of advertising like newspapers.

No one is in charge of the group’s structure, the Web site says, and it allows everyone to promote their own ideas of what the ride should be.

The decentralization spreads to the rides, which allow no central figures to be punished should there be any entanglements with cars.

In 2000, the Boston chapter got a taste of what could happen if the police decide to make arrests.

While riding with about 100 other cyclists in a 2000 Critical Mass ride, Peter Rowinsky was arrested by a Mass. State Trooper for disorderly conduct and refusing to obey an officer.

When the officer pulled in front of the cyclists on Memorial Drive, he accused the riders of blocking traffic, to which Rowinsky responded, “We are traffic.” Rowinsky was taken to the holding cell in the Brighton police barracks on $25 bail, which was promptly paid by his wife.

In the account Rowinsky published on the site, the officer later apologized that he had to be the person arrested out of the whole group, but that he had to do something.

“The cops really don’t seem to have much of a system worked out for ‘handling’ leaderless movements,” Rowinsky posted on his site detailing the incident. “This is our strength.”

For Bailey, the movement is also an exercise in his beliefs.

He uses his bike as one of his main forms of transportation, and said he’s constantly upset by the inconsiderate mood of Boston’s drivers.

“I expect lots of honking and flipping [of middle fingers],” he said. “This is kind of out there. People biking amid society. It’s to show solidarity. It doesn’t need to happen all the time.”

The environmental factors and political causes are tied to the movement through the bikes. By bicycling, Bailey said one does not support exorbitant consumption of oil and promotes a cheap, healthy and earth-friendly way of transportation.

“I’m doing this because I don’t want to pollute,” Bailey said. “I don’t want to use petroleum. It’s a daily concern, the long-term impact of life.”

Though the turnout was low, most of the small crowd was able to easily articulate their reasons for coming out.

“It’s fun and important to assert rights as a biker. It’s ecologically sound,” said Dylan , 19, of Allston. “We are part of traffic! [While riding] I’ve been swerved toward, run off the road. We are going out there in strength.”

And despite his sarcasm toward the crowd, Keller was uncompromising in his reasons for coming out.

“Capitalism ruins lives,” he said. “Driving a car is buying into the capitalist system.”

Keller, 23, “give or take a decade,” has a youthful passion for his cause (or potential causes), he carries himself as an old soul.

Through a small stature and welcoming presence, he takes his “economic” views very seriously, but clearly has a soft spot for bikes.

Keller works as a research assistant in Newton. While getting around Boston, he has formed a strong relationship with his bike.

“My bike’s name is Jeremy,” he said wistfully. “We’ve been though a lot together. “Jeremy is my primary mode of transportation. My feet being second.”

It’s the only time Keller’s voice is soft and his point is direct.

When asked what he does for a living, he answers by describing every aspect of his day from the humdrum to the detailed. “Oh, you mean as a career?” he asks without prompting. “I’m a rabbi.”

Within seconds, he produces a business card.

It was difficult to decipher if he is telling the truth or making a joke that’s only funny to him.

The card read “FREE JEWISH EDUCATION” with “Genius” under his name. To the bottom left of a giant Star of David is his online moniker: atheistrabbi.

He immediately asks before any questions, “Are you part of the mainstream?” both in serious sites and Wikipedia to make his point against “mainstream” media.

As it became clear that no more people were going to show up, the bikers left from Dartmouth Street and hit the roads of Boston, making themselves known to the unapologetic automobile drivers of the city.

They rode off into the biting wind, their chanting were muffled under the honks and sirens of Boston’s traffic.