Sounds kind of big with 19" in back, but you can't strictly go by your height. The best way to tell though is go give it a test ride. If it fits, decide if you want it. If not, let it go. The link is completely ball park and by no means necessarily correct. You can possibly get away with a little big for the stoker as they don't have to put a foot down when you stop, but they do need to be comfortable. FWIW, I am 6'2" and my fiancee is 5'4". Our tandem is a 20" in front and a 17" in the rear and fits us perfectly with a decent length stem and a couple of inches of saddle to bar drop. I don't feel cramped and she doesn't feel too stretched.

http://bicycling.about.com/od/howtor...MTB_sizing.htm