The Thomson seatpost FBinNY reference was designed with no setback to allow the post and the bottom of the saddle clamp to be made all in one piece for strength. Apparently Mr. Thomson had a two-piece seatpost break while he was riding and was determined to make one that would never happen to.

Thomson makes a "setback" seatpost by bending the cylindrical portion of the post backward slightly. The "kink" is about 3" below the saddle clamp which limits how far you can lower seatpost into the frame.