I'm on the market for my next mountain bike. spending the time to research my options. I'm currently focused on the Specialized Epic, which stands out thanks to the Brain shock. In addition to a mountain of positive reviews floating around the net, I looked up the patent application with the US Patent Office ("United States Patent #6,267,400"). There's some interesting information in the patent app, including schematic drawings and stuff.

Here's the abstract from the patent application:

"A bicycle shock absorber for differentiating between rider-induced forces and terrain-induced forces comprising: a first fluid chamber having fluid contained therein; a piston for compressing the fluid within the fluid chamber; a second fluid chamber coupled to the first fluid chamber by a fluid communication hose; and an inertial valve disposed within the second fluid chamber, the inertial valve opening in response to terrain-induced forces and providing communication of fluid compressed by the piston from the first fluid chamber to the second fluid chamber; and the inertial valve not opening in response to rider-induced forces and preventing communication of the fluid compressed by the piston from the first fluid chamber to the second fluid chamber."