I have been studying the various rear suspension designs found on different quads and I wanted to ask about the linkage that is found on some.

For example, on some quads the rear shock is attached directly to the swingarm but on others the shock is connected indirectly to the swingarm via an additional pivoting link. Exactly what does the linkage do for the rear suspension?

Does the linkage provide more wheel travel? Or does it allow for a lower shock placement on the frame? Also, does it have anything to do with the leverage ratio of the shock?

Is there a real benefit to having linkage on a rear suspension system, or is this really something that is model specific as far as quads go?

(I originally posted this on "Performance Mods & Mechanical". Later, I noticed this forum specifically for suspension so I copied it to here.)