I already wrote previously about my Bike Friday Family Tandem. I used it for over 2 years in the configuration it came in: flat handlebars with Sachs (now SRAM) 3x7 Dual Drive shifting. I prefer drop handlebars, so last winter I decided to switch out the handlebars.
Switching to drop handlebars on this bike requires a few other changes. First of all, I needed a pair of 3x7 Shimano STI brake/shift levers, which various online sources claim are compatible with the older DualDrive hub/derailleur combinations. Shimano hasn't made a 7-speed shifter for a number of years, so these have to be bought on the secondhand market, but even then they are hard to find because Shimano had already gone to 8 speed on their high end drivetrains when they introduced STI in the 1990s. The one exception is the RSX shifter, which presumably was sold on some lower end road bikes in that era, and comes in a 3x7 configuration. I found these RSX shifters on eBay.
One problem these shifters had when I bought them was that the smaller levers (the ones that shift to a smaller chainring or rear cog) did not engage. This apparently is a fairly common problem with these shifters and it is caused by the old grease getting sticky. I can confirm the claims made by others on the internet that this problem can be fixed relatively easily by spraying degreaser into the shift mechanism a few times, followed by a light lubricant, which eventually frees up the mechanism.
The brakes on this bike (drum brake front, V-brake rear) expect a longer cable pull than STI shifters are capable of generating, so it is necessary to add the Problem Solvers Travel Agent. I've used them on another tandem already and they work great. They come in two varieties, one for V-brakes and one for disc brakes (or drum brakes), so I installed one of each type. Here's the rear V-brake with Travel Agent installed. It replaces the curved "noodle" normally installed between the cable housing and brake.
The disc brake version comes with a hole at the top so that it can be attached to the fork using a cantilever brake mount. This fork doesn't have cantilever mounts, so I attached it to the fork with zip ties and used a piece of inner tube around the fork blade to prevent scratching the paint and hold it in place. So far, braking performance both front and rear with the travel agents installed has been great.
The left shifter, which normally goes to the front derailleur, has worked fine operating the 3-speed internal hub. It takes some getting used to because when connected to this hub, its operation is backwards from a front derailleur: the large lever shifts to a lower gear rather than a higher gear. The combination of the right shifter and rear derailleur has been less than ideal so far. The cable pull for each click isn't quite enough for the derailleur. It's adjusted so that it works OK in the middle of the gearing range, but starts to miss shifts as I get out to the edges. It's possible the derailleur or shifter are just old, but the original grip shifter that came on the flat handlebars worked better.