I have 5 Volkl PB10 mid . My prefer MGR/I° is 20,90 and the best swingweight with this racquet seems to be for me 325: better manoeuvrability with lesser weight possible .
Two of them SW are 331 with higher balance (+0.2) and weight( +2g) than the others and MGR/I° is 20,70 .
I used paper glass to sand the bumper ( from 3 to 9 o'clock) and decrease it easily 2g .
Now the result is the same for the 5 racquets: 339g strung , Balance 31,7 , swingweight 325 .
Sanding the bumper, MGR/I° has increased from 20,70 to 20,82 .
Now just adding 5 g surgrip, the MGR/I° is 20,90, SW 325, 344g, Bal 31,4.
Question: is it acceptable to increase MGR/I° sanding the bumper ( 2 g is very easy) when you accept or need to decrease mass, balance, and SW or do you always prefer to increase weight at 7" to increase MGR/I° ?
Or are you always wrong sanding the bumper (increase flutter at the top of the racquet ?) .
Because for some racquets ( Becker London for example), if you don't sand the bumper you need to add a very high mass at 7" to increase MGR/I° to 21 ( 15 to 20g) .
For a Babolat APD you will probably need 20g at 7" to obtain MGR/I° 20,90 .
For a Volkl PB 10: 8 g at 7" and a 5g surgrip will increase the weight at
356g and MGR/I° 20,90 .If you decrease the bumper for 2,5g you will obtain the same MGR/I° with only 345,5g which is more acceptable.