Balance Hole & Equipment Specification Update

By Matt Stevens
October 9, 2019

As a bowler you should have heard by now about the changes that are coming to bowling ball specifications.

What does that mean for you and your bowling equipment? We hope we can help break things down a little and explain.

Following three years of research on how technology has affected the sport of tenpin bowling, the United States Bowling Congress (USBC) released a statement in April 2018 regarding proposed new ball drilling and bowling ball cover stock specifications. 

Late last year, TBA received communication from World Bowling regarding the changes to the rules for drilling specifications.  TBA Rule 603 was revised to define the current balance rules, with the new rules taking effect from January 1 this year and the final rules that will apply after August 1, 2020.

Jason Milligan from the Equipment Specification & Certifications Department of the USBC answers some common questions below.

Q: When a bowler delivers his ball, he has the tip of his thumb in the hole drilled as the original balance hole. Does that mean he is using a “thumb hole” and that the original thumb hole becomes a balance hole, rendering the ball and the delivery illegal?

A: The thumb would need to be inserted enough that the bowler can actually pick up the ball in that manner, in effect showing he can “grip” the ball or use the hole for “gripping purposes” for the hole to be considered a “thumb” hole and allow him to also have a balance hole. If that is not the case, then the hole is a “balance” hole and it just happens that his thumb tip rests on the balance hole. The addition of another balance hole would make the ball and delivery illegal.

Q: Have you ever heard of a ball being delivered by a bowler using the tip of their thumb only?

A: Tip of the thumb only, I have not heard of that grip being utilized. I have seen bowlers remove their fingers from the holes and just use the thumb for spare shooting, and that is allowed.

Q: Is there such a grip?

A: I don’t believe so, no way to hang on to the ball that way.

Q: What is an indentation?

A: Indentations were popular for early no thumb bowlers and for people who had physical limitations due to injuries or disabilities. An indentation is severely pitching the hole in a way that the drill bit only grazed the side of the ball creating an indentation or channel for the digit to lay in.

Q: Can a bowler have a thumb hole 4mm deep and if so, is that an indentation or a hole?

A: A hole drilled 4mm deep is still a hole, not an indentation.

Q: If there is an indentation in your ball, can that ball have a balance hole as well?

A: For gripping hole allowances, we consider a gripping hole and a gripping indentation as the same thing. That is why you are only allowed to have up to five, and all for the digits on one hand. For that reason, I would say you can’t have an indentation for your thumb and a balance hole.


TBA Rule 603 was revised to define the current balance rules, with the new rules taking effect from January 1 this year and the final rules that will apply after August 1, 2020.

In Summary:
From January 1, 2019 to August 1, 2020, there are two bowling ball balancing systems

  1. Balls greater than 8 pounds without a balance hole must comply with Balance – A or B rules. Refer to Rule 603
  2. Balls greater than 8 pounds with a balance hole, must comply with Balance – A rules. Refer to Rule 603
  3. The purpose of the two rules is to start the process of plugging balance holes and to check all balls comply with the new rules.
  4. Balls greater than 8 pounds cannot have more than 3 ozs between any two halves.

From August 1, 2020, no balance holes will be permitted.

Therefore, if you plan to purchase a new ball before August 1, 2020, you have two options: #1) Drill the ball without the balance hole in accordance to new rules or #2) Drill the ball with the balance hole in accordance to current rules.

Q1: What does this mean for you and your current equipment?

A: If you currently have balls drilled with balance holes in them, you may use them legally until August 1, 2020, as long as the ball has only one balance hole when making a delivery. You will have until that date (August 1, 2020) to plug any additional non-gripping holes. (This includes drilled thumb holes for no-thumb bowlers, as that is technically not a gripping hole used each delivery.)

Q2: I have a 15lb ball with two finger holes and a thumb hole, but no balance hole. Is it legal to use?

A: Yes, as long as all holes are used in the delivery (refer Q3 and Q4) and the ball satisfies the weight allowances defined in Rule 603 and Balance rule A or B.

Q3: Can I deliver the ball in Q2 without using the thumb hole?

A: Yes, as long as the ball satisfies Balance Rule A. In this type of delivery, the thumb hole becomes a Balance Hole, but only until August 1st, 2020, when all Balance Holes become illegal.

Q4: If the ball in Q2 had a Balance Hole, can it be delivered without using the thumb hole?

A: No. Until Aug 1st, 2020, a ball is permitted to have only one Balance Hole. If a ball has a thumb hole and a Balance Hole and the thumb hole is not used, then that hole becomes a Balance Hole and the delivery would be illegal.

If you don’t have balance holes drilled in your ball?

Just keep up the great bowling! Your ball will still be legal. You can find the latest Tenpin Bowling Australia Limited League Tournament & General Playing Rules book here.

Still have questions ?

Contact the Tenpin Bowling Australia National Office on (07) 3262 4455 or send us an email [email protected].