I know Jesus said to forgive those who trespass against us, and Mohammed probably did too, and there's got to be a few awesome Hindu epics about forgiveness (maybe very long, and probably in verse). The Buddha would effortlessly forgive everyone just by being that way, and one of his distant followers would write a koan about it.
They would all be right, of course, even if I didn't care a whit about the victim, because forgiveness is probably pretty good for your inner self (whatever you think that "self" is).
However, righteous indignation feels pretty good too, and maybe if more bike thieves and bike part thieves were able to experience the effects of said righteous indignation from me or others who have recently lost a bike (or bike parts), there might be fewer bike thieves. Because if I saw you, I would beat the snot out of you*.
*or rather, I wouldn't do that, because I know the consequences would be worse for me than you (even though a bike thief is a far shittier person than one who punches a bike thief), but I'd like really yell at you a lot and probably call the cops and then fume about how you got let off with a small fine or something. Maybe more about this later.