Critical Mass is cute and all, but bike commuting on a daily basis is real. CM, as fun and exiting as it may be, is a temper tantrum that alienates more than anything else. If you actually want to see the number of cars reduced and the number of bikers increased, you want to show the driving public that bike transportation is safe, normal, and practical. A driver has to see themself on the bike, not cower in confused terror while bands of vicious bike rebels ransack the streets.

Or we could just ban or severely restrict personal automobiles from urban centers... (you'd think parking issues and gridlock would be enough, but obviously not)