Last friday, I joinded the Critical Mass Graz. It was by far not as critical as I expected, but I was told there were normally more cycling enthusiasts joining the monthly ride. There was a demonstration scheduled for the same time, and the not soo nice weather probably did the rest.
Peoples reactions are mostly big smiles, but also (especially car drivers) occasionally call you a stupid jerk.
If you have never heard of Critical Mass, you may want to read the wikipedia article:
Critical Mass is a bicycling event typically held on the last Friday of every month in over 300 cities around the world. While the ride was originally founded with the idea of drawing attention to how unfriendly the city was to bicyclists, the leaderless structure of Critical Mass makes it impossible to assign it any one specific goal. In fact, the purpose of Critical Mass is not formalized beyond the direct action of meeting at a set location and time and traveling as a group through city or town streets.
The next Critical Mass in Graz will be on the last Friday of October, wich is the 31st!