The london trick beef? a.k.a 5th Floor Fixie Crew Implosion

This is absolutely hysterical but on a serious note I can think of two reasons why this may have escalated into violence:

1. People who do tricks on fixies really are pricks.
   
2. People who do tricks on fixies know about their reputations as being pricks and attempted to do something about being teased using the same brains that decided doing tricks on fixies is cool.