KOP is knee over pedal. You know how when they set you up on a bike they adjust the saddle fore-aft position so a plumb bob dropped off your knee bisects the pedal axis. But on a Brooks, I find I slide back to get my proper KOPS length regardless of where the saddle sits on the rails. But, clearly some positions are better than others in terms of sit bone support. I also realized you want your saddle quite a bit wider than your sit bones, again to avoid having your sitbones be on top of the metal frame. I think that may be why some folks are never comfy on their saddles. The leather hangs like a hammock from the frame, and your sit bones need to be sitting on the hammock and not the frame! It may feel better than a gel saddle, but then it never really breaks in. Mimi- you would love the shop that sold me the bianchi seatpost. They specialize in Italian bikes and parts, many many bianchis, they do custom colagnos and serottas, mostly campy, etc. BUT, I also learned that Bianchis all have too steep a seat-tube and too long a reach for me . Even though I don't ride a bianchi, they liked me cuz I use a Brooks saddle (they are also very big on Brooks) and ride bikes made of steel and ti. They are very anti-carbon. -e