Why would you ride in a critical mass event?
I used to live in the SF Bay Area, and liked to do all sorts of bike riding. My friend talked me into it, saying it was a fun and different experience.
It was certainly different. Bicyclists would block traffic and even pound on people's cars at intersections in an attempt to keep the group together, because slowpokes would get caught at red lights. The parroted phrase from motorists was "I'm on my way to the doctor!", because only then did the motorist own the moral high ground, and those folks were allowed to pass.
I saw open drug and alcohol use, besides me. There were naked dudes. All the while, 1 or 2 motorcycle cops followed the group at about 8 miles an hour, to prevent accidents. I talked to the cops, and even made one laugh with a comment about how I felt sorry for him due to the horrible smell of those hippies.
They said they were not allowed to enforce any of the laws that the riders were breaking - they just did traffic duty and kept the riders from getting rear-ended.
It was a mostly harmless thing. I have been around hippy wastrels my whole life and was used to their childish antics; I just liked riding with a big group.
Then, next month America started bombing in Afghanistan, and I went to a FReeper counter protest in Dolores Park and those same people were threatening to kill me and my then-GF now wife, and six other brave FReepers. I had to escort our people from the median as a thousand people came at us. One hippy dude smoking a doob even told my GF to go back to Europe!
And I never participated in a Critical Mass ever again.