I've been curious about this thread as well as I'm looking to get into a Triumph. I currently ride a Vulcan 500, but am ready to upgrade and I went to test ride an America. It was great, but the the dealer put me on a Thunderbird and I haven't been able to get that out of my mind ever since!
There are more used Speedmasters and Americas out there and for a lot less bread than a Thunderbird, so it seems like maybe a good choice to just start with a smaller Triumph. But am I gonna be longing for the T-Bird even if I get a new Speedmaster/America? I'm thinking yes, especially after reading threads like this one. I'd also like to hold out for a bike with ABS. It rains a lot here in Oregon.
But coming up from a Vulcan 500, I wonder if I should just make a small size jump to my next bike. By that I mean get the 1600cc Bird instead of the 1700cc
Ok one thing to keep in mind when reading a thread like this is very
few people that pay $5,500 to $6,800 more for a motorcycle will ever say it is anything other than superior to their previous ride.
Also read through the tech forums of both bikes, look at problems people are reporting not modifications. Coolant leaks, belt noise, electrical, paint issues etc. Compare newer bikes of course.
As far as physical size the America and Thunderbird have almost identical wheelbases and the America is slightly longer overall. The '11 and newer Americas have 10mm lower seat height than the T-Bird and of course 200lbs less weight.
I rode each bike several times and liked them both. To me the much lighter America was more agile and the T-bird more straight line stable.
In the end I prefer the essential classic style of the air cooled America. As others have said the Thunderbird looks like someone put a parallel twin in a Japanese cruiser. In a few years I may want something different, perhaps by then Triumph will work the T-bird's style out.
...go ahead, fire away.