Fellow Tracksters,

I responded in the misc forum on this subject and thought it might be helpful here as well.  

Radius of Gyration(RG) -  controls how fast a ball will rev up, a lower rg ball revs up faster and a high RG ball revs up slower.  The differences between the two are that a lower rg ball will react sooner on the lane vs a high rg ball that pushes down the lane and reacts later.

Differential - this controls the flare on a ball.  The higher the flare potential, the higher potential for hook/movement.  The lower differential balls have less potential for hook due to lower flare capabilities.  Just look at your track on old urethanes and plastics, the flare should be very small/minimal in comparison to your high end resin/particle.

http://columbia300.com/innovation/techdocs.cfm?id=5

Cores/weightblocks - As we've seen, there are many core shapes that exist.  The shapes tell us to some degree what to expect out of a ball in reaction.  However, that has changed with the technology of varying densities in the weightblock.  We can take a core with 2 flip blocks one on the top and one on the bottom, now change the density of the top block and it can change the reaction without actually changing the shape.  This is done by altering the rg and overall differential.  This is a very basic understanding and definition of ball reaction and motion which is definitely more complicated but I thought this might help some.  I'll get into mass bias on a later post.
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Rick Leong
Ten Pins Pro Shop
Track Amateur/Pro Shop Staff
Vise Grip Staff

Hey ... What about the Lane Bed?

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EvEryOne rOlls OveR tHe LanE Bed