John Jeffries - Phoenix, AZ
Why is it sometimes people roll over thumb hole on one ball but not another?
Josh -The reason someone rolls over the thumb has all to do with how they release the ball. The more your hand rolls off the ball, the lower your track usually is and can sometimes roll over a thumb. In your question, why does it do it on one ball and not another, all has to do with the dynamic of the bowling balls core. When a bowling ball has a lower RG core with higher differential, it will want to start flaring "roll away from the thumb" quicker than a plastic or Urethane ball. Because plastic balls don't typically have cores, they will not flare and the bowler will see the ball roll over their initial track all the way down the lane.
Craig - For players with very low tilt or negative tilt, they will get very close to the thumb hole or roll over it. The key factors that determine whether or not the ball will roll over the thumb hole is 1. How much you loft it and 2. The core type of the bowling ball. To understand why these are the key factors, let me explain a little. If you have ever looked at a bowling ball with oil on it after being thrown, you can sometimes see rings of oil. These are called flare rings. Each rotation that the ball experiences as it goes down the lane, it has the core pushing on it making it move a little and making the ball roll over a new, fresh part of the bowling ball each time, creating these flare rings. The bigger and more influential the core is, the bigger the gap between the flare rings because it's pushing even harder on the ball. When you let go of a ball, believe or not, it flares in the air. This means that the core is still pushing on it in the air, so if your initial oil ring would be over the thumb, but you have a big strong core pushing on the ball, then by the time it hits the lane, it has "flared enough" to be off the thumb hole. Additionally, if you loft it more, the ball has more time in the air to flare before hitting the lane. Situations like yours is where Bowler ID and Blueprint are really useful to help insure you get the right layout to maximize flare potential and help the ball get off the thumb hole as quickly as possible. The general rule is that the balls that don't roll over the thumb will either have lower RG or higher differential.
Nicholas Kelley - Modesto, CA
How do i know if i need to change my pitch and/or span?
Josh -Thank you for the great question Nicholas. Spans and pitches are a science and takes knowledge of the bowlers past and where they are wanting to go to get it perfect. Most of the time pitches are made with educational guesses and not always 100% the first time. This is why it is important to keep in contact with your Pro Shop Operator to develop a relationship so if changes are needed, they know how it needs changed.
Typically spans and pitches are only needed changed if a bowler is suffering from pain in their thumb/fingers or they are trying to change their release to get a more desirable ball roll. There are cases where bowlers don't change their span for 20 years and start to develop wrist pain because they are not as flexible now as they were when they got fit in the 90's. In both of these instances, it is important to help your PSO fulling understand what you want to accomplish so they can do their job.
Craig - The first sign is any kind of blistering, callusing or pain in the hand. I have worked with so many people over the years who believe they are cursed with some unique hand that is meant to look like roast beef. This just isn't the case. Unless you have a very serious physical ailment or condition, you should be able to bowl several games regularly without blistering, callusing or causing damage. With that said, it also requires commitment from the bowler to understand how to properly grip a bowling ball. The other common misconception is that the right fit should come off the hand perfectly with no pain no matter what the bowler does. To compare to this golf, a golfer can get clubs fit for him, but still blister his hands or cause injury to himself based on how he grips the club or swings the club. It's important to have the correct fit and also understand how to properly grip a bowling ball aka learn to not squeeze with the thumb so much. Make sure to find a good pro shop operator to help you out with this. This is an area where you will want knowledge, but also patience. They can know everything in the world, but if they aren't patient with you, it won't matter how much they know. It will require you time to learn for yourself that it's the right fit for you because it's a "feel" thing, not something you can logically know is correct.