2 weeks ago i had a crash and i broke my back shift, which is a shimano tiagro. Today i had my bike again and went in to small ride, i stopped in the traffic light and when i startet to move my back shift broke again!
Looks to me like you need a new derailleur hanger... that piece of broken metal there is the hanger. Also because of the tangle there you probably want a new chain and maybe even (if an expert says so) a rear derailleur. Or as you're calling it, "back shift".
What might have happened is that hanger was weakened in your crash, but not replaced. Was anything replaced when you crashed a few weeks ago, and what was replaced if anything?
edit: sorry for double-post, I can't find a delete button.
Yeah, broken derailluer hanger. Looks like you will need to replace the rear derailluer as the idler arm is bent. You will also need to have your rear wheel at least trued, but you will probably need to have a couple of spokes replaced. With that tangle, a new chain would be advisable. You might also ask them to check the chain stay and seat stay on that side as there appear to be some significant scratches in them that could possibly compromise the structural integrity of the frame.
