WRT the thing hanging off the drive side of the bike, it pains me to admit that the Davidson does have a derailleur on it. At least it is a Sach/Huret Duopar Titanium. I'm going to be installing a SRAM S7 hub onto the Fiorelli to see how suitable it is for tandem use. If it is successful, it is possible that a Super 7 may make its way onto the Davidson. I would probably redo the drivetrain so that the chain is driven entirely off the right side of the bike since I wouldn't have to deal with multiple chainrings. It's not something I'll be doing any time soon, if at all, as I have far too many projects in the queue at the moment.