Tips for getting a consistent feel in your thumb hole
When you are getting in to bowling more heavily and building an arsenal, one of the biggest variables for your release is having a consistent thumb hole. Interchangeable thumbs were introduced 25 years ago and were revolutionary. They provide even more consistency than the thumb slugs that we recently reviewed because you can make one thumb hole that fits every bowling ball that you buy. There are a couple of systems that grip companies have developed. One is a tab system with a lock at the bottom. Another has a screw-in type like a bottle cap. These companies have perfected their systems over time. If you are a feel bowler and you need the thumb to be exactly the same from ball to ball, it’s highly recommended to invest into one of these systems.
If your thumb changes, you can have multiple interchangeable thumbs with different sizes vs using tape to get the feeling just right. I’ve seen people have 5-6 different thumbs. The only downside to consider with these products is that they are made out of plastic, which can wear out. USBC rules say everything has to be made out of something non-metallic, which means it’s less durable than something made with metal. Costs for these systems can vary. If you end up investing in this product, go to a qualified Pro Shop Operator who is experienced in installing them. If they are installed incorrectly, you’ll have issues getting the insert in and out, locking it, or breaking it due to excessive force, so do your research.