The recent Courteous Mass bicycle ride distinguished itself immediately from its rambunctious cousin, Critical Mass.

An organizer handed out route maps to riders as they gathered last Friday in downtown Atlanta's Woodruff Park, along with a set of rules. Foremost among them: Stop at all red lights and stop signs.

Critical Mass, the international bicyclists' movement that takes over city streets on the last Friday of every month, is all about cyclists owning the road for a couple of hours. "Corking" intersections is its trademark, when a few cyclists block traffic through light changes to allow the entire mass of hundreds of riders to stay together. It's part protest of cars' dominance of the roads, part rolling street festival.

At the very least, Critical Mass forces motorists to see what it's like to be a second-class vehicle on the road. At worst, it antagonizes drivers trying to get somewhere during Friday rush hour.

While Critical Mass flouts the rules, Courteous Mass followed them, to make the same point: Motorists need to share the road.

"A lot of people —- cyclists and motorists —- are aggravated at Critical Mass because we ride through intersections," said Connie Kassor, 25, an organizer of the Courteous Mass ride that drew more than 100 cyclists. More than three times that number routinely show up for Critical Mass.

"I see [Courteous Mass] more as an experiment to see what would happen if more cyclists were out on the road all the time," Kassor said. "Gas prices aren't getting any cheaper. We want to show there are a lot of cyclists out there that do obey laws."

Bicyclists also want better facilities, from bike lanes to racks. In 2006, Bicycling magazine ranked Atlanta as one of the three worst cities in the nation for cyclists, in part because the city had narrowed McLendon Avenue and other neighborhood streets with concrete curbs.

At the halfway point of the Courteous Mass ride in Piedmont Park, one of the cyclists, Michael Ng, 22, said he supports both Critical Mass and Courteous Mass, but sees the virtue in following the rules. "You can't really be breaking the law all the time and expect people to support your cause."

During last month's Critical Mass, Atlanta police on motorcycles and in cars redirected the cyclists and enforced the traffic laws.

Riding with Ng, Gabriel Charvat, 31, said he thinks Critical Mass is safer for cyclists because the mass stays together, taking over an entire side of the road. On Friday, motorists were able to pass the cyclists who kept to the right side of the street, per Georgia law. Groups of bicyclists frequently found themselves sandwiched between cars.

After the ride, Kassor, who lives in Atlanta's Lake Claire neighborhood, called the night a success, albeit a slower and less exciting version of Critical Mass. It took more than two hours to complete the 12-mile ride, about twice the time it would have taken Critical Mass.

Also, because of all the red lights, the Courteous Mass riders quickly broke up into three separate packs.

"Because we weren't such a huge group all together, I don't think we were as noticeable as the Critical Mass rides," said Kassor, who is studying Buddhist philosophy at Emory University. But unlike at Critical Mass, she also didn't hear any honking car horns.

"I think it was a good opportunity for cyclists to make ourselves visible in a different way," Kassor said. She's not planning to organize a future Courteous Mass.

There was one casualty from the night. A rider crashed when he hit a metal plate near Georgia Tech and was taken to the hospital, Kassor said.

One lesson from the night for Rebecca Serna, executive director of the Atlanta Bicycle Campaign, was that no matter how law abiding cyclists are, some motorists are still going to get mad.

"There was a guy who honked at us and yelled to get out of the way," said Serna, who participated. "We were following all the rules. We were riding two abreast. But we're still not at a point in the city where we understand that bikes belong on the road and they're an equally valid transportation choice."

Under Georgia law, bicyclists must:

> Follow all traffic rules, the same as motorists,

> Ride as close to the right side of the road as possible, except to avoid hazards, to turn left, when traveling the same speed as cars or when the road is too narrow.

> Ride no more than two abreast.

> Use a white headlamp attached to the front of the bicycle and a red reflector attached to the rear when cycling at night.

The city of Atlanta is working on a comprehensive transportation plan that includes bicycle lanes and routes. A public forum on the proposal hosted by the Atlanta Bicycle Campaign will be from 10 a.m to noon on Saturday on the third floor of the Central Library in downtown Atlanta, One Margaret Mitchell Square. For more information and to see the proposed bicycle network map, go to www.connectatlantaplan.com.