On the XR400, the shock has only one compression adjustment - no "high speed" adjustment nut. As best I can tell, the compression adjuster restricts how much the oil above the piston can flow into and out of the Nitrogen bladder area. It seems that reducing the compression damping would allow the oil above the piston to flow more freely into the bladder area. This would allow sharp impacts (high piston speeds) to compress the bladder a bit and take the edge of the impact. Does this seem right? Questions: 1) Does the compression adjuster primarly affect high speed or low speed compression damping? (seems like high speed to me) 2) Does the compression adjustment affect the rebound damping? (seems yes to me, after a sharp impact) Opinions?