This is an early flier/poster for Critical Mass Los Angeles.
Nowadays these events are organized via Facebook and the Midnight Ridazz website… but back then it was paper. I would post these pieces at bike shops, along the L.A. River bike path, and give them out to cyclists.
Critical Mass grew from a handfull (I remember rides where there were only a half-dozen folks, though usually it was 10-20 or so) to rides today that sometimes draw 2000+ riders.
Other 1997 stuff coming soon.