(Via near near future), Critical Mass Bycicle Riders appears to be an interesting phenomenon... do they gather in Schelling Focal's points ??? It is close to the flash mob thing but it seems that the idea goes further.

Critical Mass is often described as an 'unorganised coincidence'. It happens when a lot of cyclists happen to be in the same place at the same time and decide to cycle the same way together for a while. Very often, those taking part enjoy it so much that they decide to get together at the same place and time the next month and the month after and so on, and to get other cyclists to join as well.