During my morning ride today, my chain went snap and pop, followed by an awful sound as the rear derailer was yanked from its mount. Luckily, it seems that the only real damage was the hanger (snapped in two). The root problem was broken link in the chain, its toast; but it was old anyway. Other than the broken derailer hanger, there doesn’t seem to be any damage to the wheel/spokes.
My question is, can I simply buy a new derailer hanger and bolt it in place of the broken one? Or does the rear derailer system need to be aligned? I have average mechanical skills, but absolutely no experience adjusting derailers other than tweaking the barrel adjusters.
The bike is a 2011 Giant Defy 1 (the Al version) with all 105 components.