Thank you for such an in-depth analysis.I wish you were my neighbour! (or at least lived closer) I also wish the guys at the bike shops had this kind of knowledge to draw from. I have a friend that is quite handy with bikes that may have the patience to walk through this with me but he's away until the end of August. I'm going to ride it again today to see how it feels to avoid those gears. I tested it out on the first ride and locked the chain up. After that a few other gears on the small ring were chattery but a simple adjustment of the barrel screw silenced those them. I guess the jamming up of the chain may have stretched something the wrong way..