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10-05-2012, 12:13 PM   #227
jstout
New User

Join Date: Mar 2009
Posts: 22

Quote:
 Originally Posted by ART ART @travlerajm: check this post with Novak racket specs: http://tt.tennis-warehouse.com/showthread.php?t=441393 Specs strung+overgrip+dampener, are: Mass: 360gr Balance: 33cm SW:371 So the MgR/I = 20,35 and MR^2= 392 Far away from the ideal MgR/I = 21,0 and MR^2= 385 Any comments about it ?
A different way to look at the MgR/I is by a pendulum period.

M = kg, g = cm/s^2, R = cm, I = kg*cm^2
MgR/I is (kg * cm/s^2 * cm) / kg*cm^2 = 1/s^2 so Period = 2 * PI * SQRT(I/MgR) which will be in seconds

Travlerajm's optimal 21.0 is ~1.371s and Djokovic's 20.237 is ~1.397s. The difference between values are generally in hundredths of a second. I've tried to collect as many measured pro racquet specs as possible and the range tends to be 19-22 (1.44s-1.34s) with the average being 20.5 (1.38s)

MR^2 is a byproduct and ranges can be very extreme: 315-450 with the average being 374. Djokovic's 392 is actually close to 385 and not far away in that regard.

I've used travlerajm's equations myself and in my opinion adjusting Swingweight, Effective Mass, and MgR/I is a good way to tweak a racquet to what feels best to you.