Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed Feb 26 21:05:35 2003

>>> Have you ever considered that the bat movement (toward the catcher) at the beginning of the swing you attribute to THT, could also be caused by the bottom hand?

Thanks, Nick <<<

Hi Nick

The bottom hand plays an important roll in accelerating the bat-head back toward the catcher. Shoulder rotation will cause the bottom-hand to exert a strong force on the knob end of the bat around toward the pitcher. But the bottom-hand exerting a force toward the pitcher is common to both linear and rotational mechanics. What makes rotational transfer mechanics uniquely different from linear mechanics (other than a CHP) is the role played by the top-hand during initiation.

For the bat to rotate about a point (torque) requires that TWO forces from OPPOSING directions must act on the bat. As I stated earlier, the direction of force of the bottom-hand is around toward the pitcher with both linear and rotational mechanics. With linear mechanics the top-hand is also directed toward the pitcher. With both hands applying force in basically the same direction, little or no torque is being applied to the bat. The knob is being accelerated linearly and the bat-head just slides over and trails behind the knob.

With rotational mechanics the top-hand is not driven forward at initiation. The direction of force of the top-hand is pulling back toward the catcher. So at initiation the hands are applying force to the bat from opposing directions. This generates torque and causes the bat-head to accelerate in an arc back toward the catcher.

Although accelerating the bat-head back toward the catcher requires a force to be applied from each hand, I termed the mechanic “Top-Hand Torque.” This is because during pre-launch torque (like Barry Bonds) shoulder rotation has not yet started and the bottom-hand remains more stationary. The bat-head accelerates back due to the pulling back of the top-hand..—Nick, during the initiation phase of the swing and as the back-elbow lowers to the batter’s side, you could think of the top-hand as just “holding back” at the shoulder (like an oarlock) while the rotation of the lead-side (bottom-hand) torques the bat-head around.

Jack Mankin