Thanks, Sheldon. The rer. der. seems OK to me, there's no signficant play in any of the pins and it *looks* straight independent of the hanger. Can the pivots seem solid and the cage still be bent or something?

It was an interesting experience. I've was told by two different LBS mechanics that the rear der. was OK, but I'm not quite sure what to believe now.

The first said the der. was fine, the hanger was fine, and offered no options. The second LBS mechanic took a look at it, ran the bike through all the gears, and then whipped out the DAG-1. He straightened the hanger., and pointed out that the long cage der. looked OK. He said that it was really flexed in the big chainring/larger rear sprocket positions, and suggested this might be pulling the rear der. over, and torqueing the hanger.

I might have misunderstood him, it was pretty quick.

However, it made sense to me that there might be enough force to re-bend an already weaked hanger. Maybe I previously bent it some other way, like if the bike fell over or got struck by something while in the garage.

How hard does the hanger have to be whacked to get bent?

The worn chain was an incidental finding. Glad to know it's not involved.

Either way, I'm going to have the LBS replace the hanger when I do their "tune-up", and see how that goes. I'm fairly confident in their work at this point, and like the attitude I got. This is a pretty reputable shop and the mechanic took the time to straighten it right then (for free!), just so I could ride that next day.

No hard sell, good service, and my BS meter wasn't pegged. A pleasant surprise these days.