Need to identify this tandem likely manufactured around 1990. S/N T9012 737. Could be additional numbers under the cable guide.
According to this thread Bob is correct. His bike is a Gary Fisher Gemini. The tandem in the thread is a good match for Bob's bike.
From the thread
I ran into a former Fisher employee at NAHBS this last weekend and was asking him about the tandem. All he could tell me was that the early ones were made in Mexico and weren't very well made. I suspect that yours and mine are later, Asian made bikes as mine, at least, seems reasonably well made. I'm still trying to figure out who designed it and decided to use the "uptube". I suspect that was the cheapest, easiest way to build it. Ritchey still uses the uptube design in their tandem, though Santana insists it makes no sense. At least it gives you a place to put a water bottle. The placement of the stoker seat tube cage won't allow the use of larger modern bottles. We use a clamp-on handlebar mount for the second stoker bottle. -- fxsvelo
Serial number on mine is 19012-0707. It has (mostly) Shimano DX components; the catalog scans I've been able to find show Suntour XC on the 91-93 models. So maybe mine's an '89. Guess it doesn't matter too much! -- rcschafer
I suspect he's wrong about the serial number based on the picture in the original question - it's probably T9012-0707
According to the Fisher catalogs for 1989 and 1990 the Gemini had a Shimano Deore II drivetrain. The Gemini was first sold in 1989, the last year was 1993. Fisher started using a Suntour derailleurs and a Sugino crankset in 1991.
Seems like Bob has a 1989 or 1990 model.
That is one gorgeous touring tandem. While I don't have a brand, here are some observations.
It is particularly long in the back half of the frame, giving the stoker a lot more room. A racing tandem is much shorter, whereas this gives more view, or more space to hang frame bags.
The big chainring is an enormous dinner plate of 58 to 60 tooth, and the grannie is fairly normal sized at 36 tooth. So this is not a beginner's bike, this bike is meant to go long distances at a high but comfortable pace.
Not sure what cassette is on it, but I'm guessing a MTB style based on the cranks being branded Deore. So perhaps 12-32 tooth. So this bike can go up most hills okay but excells in the flat-lands.
Butterfly bars also suggest a long-haul commuter, with many hand positions for the captain. The stoker can sit up and go hands-free much easier.
I only see two brakes - the front is definitely a V brake while the rear could be either V brake or cantilever. I do NOT see a drum as a third brake which is common on tandems for hills. Again this suggests being targetted for flat land use.