Riding my bike ('06 Madone) last night, my rear wheel suddenly locked up. I jumped off and found my rear derailleur had completely detached from the frame, and was entangled in the spokes of my rear wheel.
At the time I was riding at perhaps 18 mph, sitting down, and hadn't shifted for at least a minute or so. I was probably in the second or third largest rear gear, and the big gear up front. I had experienced no problems before this.
I've never crashed this bike, nor have I bumped it into anything hard, or laid it down on that side roughly.
The aftermath - the derailleur detached from the hanger completely. It stripped the threads inside the hanger, and left the hanger bent outwards. The hanger (apologies if that isn't the appropriate term) is part of the carbon frame. Once in the spokes, the derailleur took out two spokes.
This happened directly outside of a bike shop. I brought it in there - they had no guesses on how this happened. I then took it to the Trek dealer that I bought it from. Same deal - they had seen this happen on Mountain bikes, but never on a roadie.
I'm still waiting to hear from them as to what will happen to it. I guess they have to assess the situation, then potentially contact Trek for warranty repair/replacement.
Any theories as to how this could have happened? Has anyone experienced anything similar? What is reasonable to expect from Trek and/or the LBS?