All bowling balls should be cleaned after each use. This can be done by using any cleaning agent available from your favorite pro shop, or using a commercially available cleaning agent that will not leave a residue on, or damage, the ball. All balls pick up dust, oil, and other foreign substances as they roll down the lanes and up the ball return equipment. This can alter the ball's reaction by hardening or plugging the pores and on the surface. By keeping the ball clean, the ball will react more like when it was new.
If you use a dull sanded ball, and with normal cleaning the ball doesn't react as well as it used to, it is time to sand the ball. This will bring it back close to its out of box condition and reaction.
As a bowling ball goes down the lane and it crosses a seam, a small nick may be caused on the surface of the ball. Once there are enough of these little nicks to cause a loss of reaction, it is time to resurface the ball. This can be done to any ball, including polished balls. They are sanded smooth again and then refinished to their box condition. Plastic balls should be polished often to keep them working as they should. These can also be resurfaced when the need arises. Your favorite pro shop should do sanding and resurfacing so it is done properly.
It is always best for the bowler to be able to use a ball drilled for them. It really doesn't matter if they are still growing. A bowling ball can be plugged and redrilled several times before it needs to be discarded. Even as the hand changes, the weight of the ball may remain ideal for the child for 1-2 refits. Weight does not become a factor until they start to grow and get stronger. With the cost of the type of equipment a youth bowler would use, it isn't a bad idea to purchase a new ball. Even when the child grows out of it, you can always hand it down to a younger generation of bowling youth.
A custom thumb is a general term for a thumb insert that can be repeatedly made for size and pitch and can be installed in any bowling ball. There are several different manufacturers and systems available that create thumb inserts (we use Exact Thumbs from Vise Grip). What you need to do is determine which of your ball's thumb holes feels the best. Take that ball to your favorite pro shop (if they have the capability to make a custom thumb for you). A silicone mold is made of that thumb hole. This takes 24 hours. Then an insert can be formed from this mold. This can take anywhere from 30 minutes to a few hours. This insert can now be installed into a bowling ball. Using the same mold, several inserts can be made so they can also be installed in all of your equipment and have the same feeling thumb hole from ball to ball. The original ball that the thumb mold was derived from will remain unharmed and legal.
While we do have the ability to install "interchangeable" thumb inserts, we do not fully support their use. While these have been successfully used by many bowlers for many years, our experience shows that the need to have two (or more) different sized thumb inserts can nearly always be negated with proper fitting and drilling that allows for proper grip and release. Also, there is no way to guarantee that the various locking mechanisms do not break - if this occurs during a tournament or league, there is typically no way to continue to use the damaged insert and/or ball. As noted above, we are able to exactly reproduce custom thumb molds (inserts) that allow for same feel to be achieved in several balls.
RG (Rg) and differential are important characteristics to consider when purchasing a performance bowling ball. Knowing some of the basics can really help you choose the right equipment. RG stands for 'radius of gyration' and is defined as the distance from the axis of rotation at which the total mass of a body would be concentrated without changing its moment of inertia. Simply put, RG dictates when the core of the bowling ball begins to rev up.
The RG is mainly dependent on the shape of the core. Using a common object shape, like a football for example, it is easy to explain how a weight block functions.
A football can spin easily either end-over-end or as a spiral. It will take longer to make one rotation at the same speed end-over-end than it will to rotate as a spiral because the radius of the end-over-end axis is longer than the spiral axis. The end-over-end axis is rotating in the high RG plane while the spiral is in the low RG plane.
Within the football shape, RG is determined by the location of the majority of the mass. The lower the RG number, the earlier the hook. High RG means the exact opposite. The higher the RG, the more length the core will create. RG ranges from lower (2.26"-2.51", medium (2.52"-2.56") to higher 92.57"-2.80"). The lower RG is what bowling ball manufacturers typically advertise and print on the box.
With this understanding of RG, let's talk about differential and its effects on ball reaction. Differential is defined as the difference between the maximum and minimum radius of gyration, better known as the X- and Y-axes of the weight block. The RG differential indicates the bowling ball's track flare potential.
The higher the differential, the more the ball will flare. The more flare on a bowling ball, the more the cover touches the lane surface. With more surface touching the lane, the earlier the ball will want to hook. With low flare, less of the ball surface touches the lane causing the ball to create more length due to the ball surface rolling over the same part of the ball that is now covered in oil. Differential ranges from lower flare potential (0.000-0.025), medium (0.026-0.046) to higher (0.047-0.060).
How will these factors affect your decision in choosing the correct ball for your game? Let's look at an example of a ball that has an RG of 2.48 and a differential of 0.053. Based on these values above, this is a lower RG, higher differential ball that will want to get into an earlier roll while providing plenty of flare. If coupled with a higher friction (sanded) cover stock, this will likely be one of the strongest balls in your arsenal and will perform best on fresher, high oil volume lane conditions.
Comparing this to a ball with an RG of 2.57 and differential of 0.046, we have a much higher RG and lower differential, which suggests the ball will provide much more length and less flare overall. The ball will maintain a straighter line longer. This type of ball will be more suited for use on higher friction lane conditions.
Finally, a ball with an RG of 2.49 that has a differential of 0.029 will want to roll early but will create natural length with low-medium flare potential. Here, cover stock plays the most important role in governing ball reaction. A polished ball will have length and a strong, controllable down-lane motion. Removing the polish will yield a smoother backend reaction.
This information just scratches the surface of core dynamics. Hopefully, this helps simplify the selection process of your next ball. Stop in to see our product selection and discuss the various ball dynamic examples.