Posted by: Jim (jwelborn@lexcominc.net) on Fri Nov 18 07:25:58 2005

> >>> Jack, cannot admit/consider/define these rotations as the start of rotation, because then, rotation would overlap with weight shift. An overlap that could be considered the transfer of linear momentum to rotational momentum. <<<
>
> Hi All
>
> If forward weight shift develops linear momentum that is transferred to rotational momentum, you would think the best hitters would be taking longer strides and shifting more weight. But if linear momentum is not transferred to rotational momentum, the better hitters could take softer or no stride and still generate great rotational momentum. -- Let us suppose for a minute that the amount of weight shift is not a factor in generating bat speed. Could that not explain why some good hitters take longer strides while other equally good hitters do not?
>
> Jack Mankin


Interesting,

I have observed and measured two things in our pro clips.

First, different players show detectable rotation at different times when compared to heel plant. Some show the beginning of rotation at heel plant, some begin at toe touch. Most begin somewhere in between, prior to full heel plant. There certainly is NO disconnect observable between the linear positive move and the beginning of rotation. The suggestion here is that the forward momentum generated during the linear phase is being dynamically redirected into rotation because of the resistance created by the front leg (firm front side).

Second, from player to player (in 22 clips observed), there is NO direct relationship between stride length and length of hip slide (weight transfer). Some long striders have relatively short hip slide while others have long hip slide. Some short striders have short hip slide while some have long hip slide. Two no striders displayed average to above average hip slide length. All however, do have hip slide within a range of 8-20 inches with 12-14” being typical.

I believe the hip slide or weight shift achieves two things. It initiates momentum that will be used in rotation; and it creates a favorable orientation for the axis of rotation by bringing the bottom end of the axis to the front heel which results in its familiar backwards tilt.

Jim