there's a huge difference between catching the thieves in the act and trying to get your bike back afterwards. Actually, I have experienced both cases: Once my brother saw how thieves were trying to steal a bike and informed the police, who acted. Another time I saw my stolen bike basically 300m next to a police station and went there and everything they said was: We don't have policemen here who have time for this. And all I could think (I was a teenager then): WHAT? You are at the reception and not doing anything... I didn't think about stealing it back, though.... (both cases were in Bergedorf ;))

Pretty much trash, maybe $100