My wife and I rode a tandem once last year and had an awful time of it. We had signed up for a road ride this year and thought we'd give it another shot. Found a great shop in town (http://tandemcycleworks.com/site/
) and went to talk to them about what we would need. They got us set up, gave us an introduction on necessary information (your wife will have to get used to not having control) and sent us out on a test ride. The test ride went so much better than our previous experience it wasn't even comparable. It was sort of scary, but really a great fun.
On the ride the next day, we learned even more about riding together (I like having her close - much better than leaving her 1mile behind and waiting all the time) and really enjoyed ourselves. The wind was tough and we were wiped out after 50 miles, but it was her longest ride ever and we were still in a good mood the rest of the day and not cranky and exhausted.
Things we learned:
Steel is good for a tandem frame - really benficial for absorbing some road shock
Tandems can really go fast - we were able to pass a ton of people going up hills, and pass even more people going down. You may have more weight, but you also have more power! Flats will take some time to master, but we'll get there (smooth pedaling isn't our strongest suit)
Folks on group rides love tandems because they make a great leader for the paceline.
Clipless pedals are nearly a must - if you test-ride a bike, bring pedals and shoes as it will make the experience easier.
Tandems come in a ton of shapes, sizes, colors and options
The downside - now we want to buy one, and they aren't nearly cheap - the one we're looking at is $5,000 or more. I'm hoping that I can get this paint job to go with it ;-) http://www.co-motion.com/...mgotompacblthumb.gif
Websites to check out for more information (besides the above shop link): http://www.tandemmag.com/classified/ http://www.co-motion.com/ http://www.santanainc.com/
Good luck with the shopping, and make sure you test-ride before you buy - you may think it is great, but if your stoker isn't comfortable then you won't ever use the bike.