||Since the late '90s, Specialized's patented Horst-link four-bar FSR design has been the reigning champion among rear suspensions from a performance standpoint.
The term Horst-link refers to the placement of the back pivot on a four-bar rear end. If the pivot is above the drop out for the rear wheel (ala Kona, Raliegh, etc.), then it is NOT a Horst-link. If it is below the drop out, then it IS a Horst-link design (ala Specialized, Titus, etc.).
This may sound like a pretty arcane distinction, but it has tangible real world effect on the performance of mountain bike suspension. Efficient, comfortable, and utterly free of brake jack, Horst-link rear ends put the power down -- whether you're seated or hammering out of the saddle -- better than any other design. And when it comes to braking, nothing but a floating-brake equipped bike (like the Foes Inferno, or any bike with Brake Therapy) is as smooth.
Virtual Pivot Point (VPP) design bikes like the Santa Cruz Blur, Giant Reign and Rocky Mountain ETS have raised the bar in the last year or so, but Specialized and the Gang of Four (Bars) have fired back with the help of a marvelous new generation of shocks from Manitou, Fox and 5th Element. The Stumpjumper 120 Disc's proprietary Fox Float Septune rear shock is similar to the Fox Float RP3, and gives the 2005 Stumpjumper a ride so comfortable and efficient that it's actually exhilarating.
Today, in 2006, there are few mountain bike rear ends as good as the Horst-link four bar when mated to a stable platform shock, and none better.