Interesting stuff but I'm not really looking to get into a right/wrong debate - MgR/I was suggested to me as a starting point for figuring out the mass I'm adding to the handle of my racquets (and more specifically how much at 7" and how much at the butt). I don't know if it's right/wrong but my racquet feels better now that it's closer to 21, so i think it may have some merit.

But if you don't recommend paying attention to MgR/I - could you point me in the right direction? Thanks.

I'm not looking to getting into a argument either. But it seems like everyone get caught up on numbers that have no real meaning to them and may or may not be obtainable. I'm not saying that SW and MgR/I have no value or meaning they do but no one knows what it really is.

Let's assume you like a racket that weighs x grams or ounces and has a balance of y cm, inches, or points. To obtain that exact mass and balance there are an infinite (not quite but most believe it) number of z inertia values. Really there is a finite number because your accuracy goes out the window when you fine tune down far enough.

So let's assume there is a finite number of SWs, TWs, MgR/I values or what ever you want to use to measure or fine tune your racket. Let say you want to narrow down the mass to whole numbers only, and you want to narrow down the balance to millimeters only. I say that because it gives you a finite number of weights and balance points. If your racket's weight or balance is less than +/- 0.5 g or mm you will never know it no matter how good your are. If you can tell the different you can buy more exact measuring devices.

So now we are left with the Inertia of your racket. Inertia is often measured using SW, TW, RW, MgR/I, or whatever else someone may dream up. But for and 1 combination of x mass, y balance, and z inertia (SW, TW, RW, & MgR/I) around any specific axis there will be 1 period of the Racket. The period of a physical pendulum (racket) is determined by the distance from the balance point to the center of mass and the inertia around the axis. The period is the time it takes for the bracket to swing back and fourth once around an axis.

Swing tool is an iOS device app that will measure the period down to 1/1,000th of a second with usually witching 0.002% accuracy. Match the mass, balanance, and period to what you like and nothing else really matters. Match the mass, balance, and period to within +/- 1 g, +/- 1 mm, and +/- 0.01 sec and your SW, TW, RW, and MgR/I are all exactly the same.

EDIT: If you don't have an iOS device to use Swingtool you can use a stopwatch and time for 10-20-30 or more swings. Even a stop watch is so accurate you can't tell the difference.