I had a rear dérailleur go on me today. Shimano 105, broke in half right above where it attaches to the frame, right above two screws. Why would it do that?
Chain broke too. Including the rear dérailleur cable. Plus scratched paint.
I was just about to leave my house, and was shifting from front 2nd to front 3rd when this happened. Sucks. I loved riding. I rode today instead around town. Beautiful. What usually took me 50 minutes on a car, took me only 35 on a bike. I was faster than cars on intersections, sometimes going in between and taking over. That was some fun.