One of the people who participated in the event's very first ride says he expects it'll be one big peaceful pedal around the city, "What happened is that it's always been extremely peaceful, always," Critical Mass rider Chris Carlsson said. "And there's been occasionally been very minor. Incidents that have come up, fanned by media attention, calling it a war to promote ratings, 'tune in tonight bicycles and cars at war.' No they're not, we have to share the road."
Carlsson blames the news media for focusing on negative images from 1997 when police arrested a little over a hundred Critical Massers. None of the people arrested were ever charged and for 15 years since then it's been peaceful.
Police spokesperson Albie Esparza says they believe it will be again tonight, "We don't have any information to indicate that there's going to be any type of vandalism or any type of splinter group if you will. This is going to be a celebration for twenty years of Critical Mass. If you're from around here, you know this happens every last Friday San Francisco. And from previous months and years you've seen there not really any issue with this event. It kind of just happens."
But talk with people familiar with the event, and there are a fair number of critics, "I don't like it when it interrupts my bus ride home," said one resident.
While another person added, "It's just a pain."
And one driver said, "I don't like it because they affect everybody, you know."
Cycling has a huge following at San Francisco State University. In fact, you can take a class on it. As students in Jason Henderson's class rolled up Friday morning, they knew their day would take an unusual turn, "We are going to ride around the whole city and see how bike friendly the city is, actually," student Jonathan Yip said.
Henderson teaches Geography of Urban Transportation at SFSU, and he's been studying Critical Mass, "My takeaway from Critical Mass," Henderson said, "is that it expands people's sense of what is possible in urban space." He says people who participate in the event typically already ride, but they tend to feel isolated among cars. He says the event is empowering, "I do understand the concern about the 15 or 20 minutes of delayed traffic. But I would say that if you step back and think about it, twice a day, every day, there's that kind of delay. Cars are in crosswalks, cars are blocking Muni."
Student Chase Tribble adds, "Well, I think it's cool, as long as everyone stays in their bounds and no one gets too confrontational or makes it too personal."
Friday's class started with a guest lecture on safety. Bert Hill is the Chair of the Bicycle Advisory Committee, "Giving right away, sharing," Hill said. "You know, showing common courtesy is the most important thing. And traffic rules are built around that."
Critical Mass has seen conflict in years past. But from a student's perspective, it's exciting, "I've never done something like this before in my life," Yip said. "Just, for the joy of riding."
And from an expert's perspective, the 20th anniversary is big, "I think this is probably gonna be a rejuvenation of it," Henderson said.
San Francisco Police Greg Suhr says they will have extra patrols on duty in case there is any trouble. Officers will be on bicycles.
If you don't already have it, now might be a good time to download the Waze traffic app -- exclusive to ABC7 News. It's available on iTunes and Google play and you can use it to guide you around the congestion Friday night.