I think I finally got this fixed. I completely cleaned and adjusted the drivetrain. That's all it took. DURRRR. Stoker and I did a 10 mile time trial the other day with no noise coming from the drivetrain.

All the same, we're going to switch from our 11-34 cassette to a 12-26 cassette, as the 52/39/30 chainrings provide more than enough gearing range to tackle the central Florida flatlands.

Quick question--How many links should I remove from my chain when I go from the 11-34 to the 12-26? (I know I'm supposed to replace the chain when I replace the cassette, but the chain shows zero stretch, so I'm going to see if I can get away with not replacing the chain at this time.)