I try to do all my own work, but it is nice to fall back on a shop when stuff exceeds my knowledge; I pulled my roadbike off the wall the other day, last week was the kind of super nice weather I save it for, and found that I couldn't get either derailer to behave w/ my limited bag of tricks (tighten cable, check limit screws). Stopped at a shop on my way to work, they figured out immediately that the rear derailer hanger was bent and then, with a bit of consultation amongst themselves, that the internal cable for the front derailer was likely gummed with road glop. Neither cable nor derailer broken, cable just frozen by that glop into whatever position I move it to (by adjusting limit screws). They straightened the hanger for me on the spot and I made an appointment to get the FD cable freed up. Gives me a twinge of guilt for not supporting a steady LBS, but there it is, and it is nice to be able to fall back on pros...