There are many reasons your thumb may change when you bowl. Warmer or cooler temperatures, humidity, physical work and foods we eat can all contribute to these changes. One option to deal with this is to have multiple interchangeable thumb grips and switch the grip based on the current size of your thumb.
But what if you don’t have this option? Bowler’s tape is an excellent solution to fine tune the fit of your ball so you can get the best feel with every shot. The most common bowler’s tape is the black and white tapes with ¾ inch and 1 inch sizes. For most thumbs, I recommend the ¾ inch so the tape does not wrap around the wider part of your thumb. The white tape is usually textured and is recommended for the front of the thumb hole to help with gripping. The black tape is usually smooth and is recommended on the back side where your skin is tenderer.
Before placing tape in a bowling ball, determine where the flat part of your thumb makes contact with the ball by placing your fingers in and the thumb half way in. For most bowlers this is slightly towards the sides of the thumb hole.
When placing white tape in the front of the thumb hole, make sure it is about ¼ inch down from the top of the ball to avoid catching the tape on the webbing of your thumb. You should never place more than two pieces of tape in the front of the hole because it will start to change the feeling in the angle of the hole.
When placing black tape in the back side of the thumb hole, place it directly across from the white. You can add multiple pieces in the back side of the thumb hole.
If you are not consistent on the release of the bowling ball, it could mean that you have to much grip pressure. Too much grip pressure could be caused by a thumb hole that is too large, or improper pitches (angle of the hole). Once the ball is in motion, it should take very little pressure to hold the ball. Less grip pressure equals a freer swing which leads to better ball roll and pin carry.
