Top End is a company that makes performance handcycles. Here's one. It has a 27-speed drivetrain.

For an idea of just how fast some handcyclists are, check out this video I shot of time-trialing handcyclists climbing a short steep hill and rocketing down the other side. Some of these riders looked almost as fast as the able-bodied cyclists on their TT bikes.

http://www.youtube.com/watch?v=G5A5XSe7iVU