My thumb moves up and down in size depending on the time of day and the season. I have a custom oval (molded) that I pour myself from a mold. I ALWAYS have tape in the hole. When my thumb is at its largest size, I'll have around 4 pieces of tape in the hole. When the thumb is at it's smallest size, I have around 8 or 9 pieces of tape in the hole. I ALWAYS have 2 pieces of white tape in the front (grip), and I use Johnson & Johnson waterproof tape (strips) in the back, which I add and subtract as required to accomodate my thumb. The LAST piece of tape in the back (the one that touches my thumb) is the Pro-Grip black tape. I like my thumbhole snug, and I will blow in the thumbhole if I feel that I need just a pinch more "grip" - in other words it feels slightly loose, but not enough for me to add another piece of tape. When in doubt, I err on the side of "too tight". Too loose makes me squeeze.

I usually open the thumb up a bit more than it should be, then put a few pieces of white textured tape in the finger side of the thumb.  People have told me I set my tape up as a lefty would, but it's more of an "experiment and feel" type of thing rather than "it must be this or this" type of thing.
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-Ricky-
Member of the St. Louis, Missouri USBC Adult Rankings

MORE Speed = LESS time to PANIC... But since tearing my Rotator Cuff... I'm panicking :-(

Current Arsenal: MoRich LevRG, Columbia 300 Wrath, Columbia 300 Tour Boss

Soon to add: MoRich Awesome Hook(ordered), MoRich Awesome Finish(ordered), Brunswick Twisted Fury

I used to have a rather wide thumb hole - I thought it would help with a clean release because I used to cling to the ball too long and loft a lot. I have quite slender fingers and thumb, rather a ladies' hand
But after a suggestion from my pro shop owner I tried a small pitch adjustment and started to experiment with tape. I now have a tighter thumb hole, with some white tape under and at the side of my thumb, and I also blow into the hole to keep it as dry as possible (but do not use rosin for the thumb, only the fingers).
This adjustment helped me well to achieve a more relaxed grip and an easier and earlier release, with a much better leverage on the ball. The thumb hole is still not really tight, but this minor change improved my game a lot.

If you have problems with a swelling thumb, either go for the bigger hole and lots of tape for easy adjustment, or think a bout a switch grip - you can have several thumb inserts with different diameters and even slight pitch differences, and this might be the most convenient solution.

Anyway, only trial and error will yield something that works for you. If you have a ball that you do not use often (anymore), maybe start there and have the thumb hole enlarged and experiment with tape as a 1st step.
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DizzyFugu - Reporting from Germany

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