PuttingDoctor, on 05 November 2012 - 10:17 AM, said:
Dave, to achieve what you are calling a "True SBST stroke" one would have to have shoulders (the pivot point) directly above the ball / target line to achieve motion restricted to the target line.
This would have the head/eyes out beyond the ball. In the modern putting stroke we see eyes over or inside the ball. This puts the pivot point inside the target line. In this regard the putter must move away from the pivot point down the line and then back to impact or address and then be pushed out down the line following impact. The most misinterpreted point of those who attempt to putt SBST is keeping the face square to the target line. As stated this takes more manipulation via the hands. The majority of players I've tested via SAM PuttLab who are SBST have a fanning motion, open-square-closed on the line. Tiger did this for many years with high regularity. Others who try find it difficult to square long enough or exactly at impact... leads one into the political... "You're no Tiger Woods."

I slightly edited your post into two paragraphs (no wording changes). And I did this because paragraph #1 (above) is just not correct.
When you have a pure (as in nobody on this planet will ever do anything this pure) SBST stroke, there is a LINE of rotation, not a point of rotation. This LINE is parallel to the ground and vertical to your sternum/chest. And there is (roughly) a point at which your sternum and this line intersect. But where this point is relative to the ball has NOTHING to do with anything (other than where your eyes are and the lie angle of your putter).
Imagine a door rotated 90* so that the hinges are now on the top (parallel to the ground). Now draw a putter (in the putting position) on this door at whatever lie angle you wish. Heck - make the door 100 feet long and draw the putter so that the grip end is at the top left and the putter face is at the bottom right (as in100+' away). Now swing the door. The 'putter face' that you just drew stays square to the target line.
Now stand so that your sternum intersects the 'hinge line' of the door and your hands grip the putter grip that you drew on the door. Now rock your shoulders vertically with the door. This 100' lng (plus a tad) putter with a lie angle of like almost zero has a truly pure SBST motion and your eyes are 100' from the ball (and no hand manipulation is required).
If folks are doing hand manipulation with a SBST stroke, then (IMHO) they are WAY too focused on perfection of the SBST motion. Nobody will every have a pure vertical shoulder motion and (IMHO) nobody should ever worry about that. The whole purpose of the SBST motion is to keep the putter face square to the target more than does a 'gated' stroke (at the cost of a motion that is less natural). Perfection is a waste of time (again IMHO).
dave
Edited by DaveLeeNC, 05 November 2012 - 04:03 PM.