I was out for a ride yesterday and my rear derailleur come off of the hanger and was destroyed in the rear wheel. It is a long story, but I had three mechanics look at it today and none of them could come up with a reason for the failure. When it came off, it bent the hanger and stripped the threads. All three mechanics were in the same store and all stated that they believed that Trek is one of the companies that does not have a replacable dereailleur hanger. They said that the frame was shot and would need to be replaced. They suggested that I take it to a Trek dealer and see about a frame replacement. Have any of you ever had any experience with this type of problem with a Trek bike?