What exactly do these terms mean in a ball? I've tried to figure it out but it doesn't make sense to me. I've searched the forums for this subject but haven't found it. Can anyone give me a good explanation of these?

RG means radius of gyration and the easiest way to understand is visualising an ice skater...with their arms away from their body would be high RG as it would spin slower and with the skaters arms in close or tight to their arm would lower the RG thus spinning faster. Diff relates to RG differential which equates to flare potential. The higher the number the higher the potential...

You have it backwards...low RG means it spins earlier this reacting earlier or sooner abd high RG means slower or later reacting

Cover and prep/surface make up 70% of ball motion

I would say that this might be the toughest concept at times for bowlers to grasp. I will get someone come into the shop that is out reading up to try to learn more about ball motion and get this completely opposite.

The best is the argument that Ric and the one writer for BTM (Bowling this Month) were engaged in on the PBA forum. Ric kept trying to explain that while RG and Diff are factors they were not the factors that coverstock and surface were. This guy kept insisting that low RG was as big a factor as cover prep. It was classic.

Bigmike,

Ever heard the statement "a little knowledge is dangerous"?

I see it all the time in this forum, too, but SURFACE, SURFACE, SURFACE! 

The bowler imparts the speed, revs, rotation, tilt, etc., then the surface will dictate, more than any one thing, how the ball responds to friction.  The ball's surface is what's in contact with the lane, not the core or how it's positioned by layout.

Here's a easy way to understand.

When you're driving on slippery conditions, which matters more? The tire or the engine?

4 wheel drive and a modicum of common sense, but I get your point..

Lol, even with 4 wheel drive, gotta have the right tires. 4 wheel drive + racing slicks = useless.

More importantly - "and a modicum of common sense"!

Can't tell you how many times, in 3-4" snow and slush, I've seen 4 wheel drive SUV's go flying past me at 60+ mph, while I was doing 40-45 mph on a 55 mph highway, only to find them sitting in a ditch a mile or two up the road, having gone sideways into the ditch.