Every year Trexlertown hosts "Tandemonium." It's not quite as tandem-filled as it sounds, but it's still amazing and fun to watch. Last summer a pair of guys wiped out pretty bad. I don't think either were seriously hurt, but tandem crashes evidently look really awkward and painful.

And yeah, that bike is entirely cool. I'm wondering the same thing about the Zipps being able to support the extra weight...