V For Vengeance
I could never condone taking physical retribution on a bike thief. Oh no, indeed - that would be wrong.
But this, via the ever-stylish Velorution is pretty funny:
It may or may not be fake, but it also contains the clue about why tackling someone in the act might not be such a good idea - no matter how red the mist before your eyes. Turns out that the would-be thief has a knife, but in this case doesn’t get to use it.