I'm considering changing my thumb pitch from 3/8 reverse to 1/4 reverse. My question is,does there need to be a corresponding change in either my span or lateral thumb pitch?
Current MF cut span:4 11/16,1/4 left,1/8 reverse
Current RF cut span:4 5/8,1/4 right,1/8 reverse
Current thumb pitch:3/8 reverse,1/8 right
 I do use finger and thumb inserts.
--------------------
The more I practice,the luckier I get.

You are only shortening the reverse, I think Bill Taylor said any 3/8" move will result in a span correction. So your good there. You wont need to make any lateral pitch moves with your thumb, unless you are going to try and performance fit your release. Bill Taylor called this "Using lateral thumbhole pitch to shift track"
Mo Pinel has improved this theory with "Performance Fitting"
There are moves you can make to your laterals/Linear on all gripping holes to increase/decrease rev rate,axis tilt & rotation.
So if your pleased with your release, and just want to try out the 1/8 more forward go for it. It will not have that much effect just a lower G.S.I. & E.P.

Edited on 7/7/2010 12:43 PM

G.S.I. Is Grip Strength index and E.P. Is your explosion point.

Grip Strength index measures the ease a bowler can hold onto the ball. The easier to hang onto the ball the easier it is for the bowler to get the ball to the bottom of the swing without dropping or squeezing the ball.
Your GSI = pitch of middle finger plus the pitch of the ring finger plus the pitch of the thumb. positive numbers for forward pitch and negative numbers for reverse pitch. An example my MF is 1/8" Reverse RF is 1/8" Reverse and thumb is 1/8 Reverse so -1/8 + -1/8 + -1/8 = -3/8" GSI.

Explosion point measures the strength of the bowlers release, Increasing the EP will make the release stronger, while decreasing will make it smoother. The smoother the EP the easier it is to control the breakpoint.
Positive numbers in fingers for forward and - for reverse.b Use +for reverse in thumb and - for forward.
EX. Point = the pitch of the middle finger plus the pitch of the ring finger. Now divide by 2. So MF is -1/8" + RF -1/8" = -1/4" Divided by 2 = -1/8" now add the thumb pitch of +1/8" and we have an Ex. Point of 0.

djmrely, just curious, where did you read this ?  I have never read or heard about any of that stuff that you said and I have gone to many ball drilling seminars.

cmurder300 is correct. This is a method taught by Mo. The class is full of new information and well worth the time and money to be there.

Trust me.....this is not used in the REAL world....IBPSIA or not....
--------------------
Formerly BrunsRico