I have extensively tested Travlerajm's MgR/I formula on mine and others' racquets over the last 1 1/2 years, and have proven it's truth many times over.
I'm sure MgR/I could be modeled in a lab using a pendulum of known mass with a freely rotating joint attached to a tennis racquet with a MgR/I matched to the pendulum, and measuring the acceleration over many points of the racquet tip to the acceleration of the freely rotating joint of the pendulum over 1 period.
The formula's worth can even be proven visually. Maybe I'll try to post a video, but if I compare a perfectly tuned racquet to one that has a MgR/I that is too low or 'slow' and 'shadow' swing my forehand very slowly from backswing to follow through with a loose wrist, the racquet head with the 'slow' frequency will lag behind my hand after the backswing and through the contact zone. The tuned one will stay in the same plane with my loose wrist joint all the way through. This works as well using a continental volley grip and tracing a 'U' in front of your body. The tuned one's stringbed will stay in a constant angle to the wrist while the 'slow' one will fall behind the hand while tracing down the 'U' on both sides. The same can be applied for the 2HBH once well tuned, and even the beginning of the serve motion.
IMO, naysayers can prove it to themselves with enough dedication (since there is a learning curve). It took me a few months of testing at a wall and shadow swinging slowly in front of a mirror to even know what to feel for by following the procedure Travlerajm linked to above.
My ideal happens to be close to 21 for my semi-western FH (20.93 if I use a western FH) and around 22.5 for my 2HBH. I am 5'9" with average length arms. These values are tuned for me using any weight of racquet, as long as the balance and SW are changed to meet these values. I just also happen to prefer the effortless power, stability, spin, shot directionality regardless of incoming angle/pace/spin, and repeatability of shot that the high SW gives me. Because of this, I must then also use a high weight racquet with HL balance meeting the MgR/I requirements if I want my racquet head to be synched with my wrist. To use a frame with a SW in the 365 range really just means that 30 or so grams must be added to the top of the handle (of a prostock or light starting frame) if I want my frame to swing synched with my wrist, and this ends up making the SW much easier to wield. Thus, there really are no tradeoffs for me by using a frame like this. What I have learned has just corroborated and given further credence to Travlerajm's discoveries.
Head TGK 238.1 16x19 a little shortened, 384g, 31.88 cm balance, 366sw
Babolat Tonic Gut 16g / ZX Monogut Natural 16g 61/49 lbs.
Last edited by TaihtDuhShaat; 09-10-2012 at 10:47 AM.