HOW TO LOWER THE SWING WEIGHT OF YOUR HEAVY US K90 by Michael Chaho

Discussion in 'Racquets' started by Pro_Tour_630, Mar 15, 2007.

  1. Pro_Tour_630

    Pro_Tour_630 Legend

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    Well as you know my US K90 with a 16g Poly came in at 335 SW with 32.5cm balance at 360grams. I shaved off bumper, replaced leather grip with synthetic, strung it with a lighter 17g synthetic string and removed foam material from top of grip and added 5grams of lead to buttcap;and Voila!!!! a 305 SW strung K90 with 30.5cm balance at 345grams. I had successfully lowered the SW of my US K90 a whopping 30 points!!!!!!!!

    Normally strung with a regular 17g synthetic without any modification, a US K90 swings at around 330. If you decide to string with a full 16g Poly that will bump up your SW around 5 points.

    Anyway, this new 305 SW US K90 is not even considered an Asian K90, it is lighter. It might as well be called (K)ajun. It is very maneuverable and lost some of its stability. I think I have gone over board with lowering the swing weight of the US K90. Some where between 335 SW and 305 SW there is a magic # and that magic # might be 320, a true Asian K90. I might just add 10grams of lead around 3/9 and see how it goes.

    Will keep you updated.

    Just some ref posts

    http://tt.tennis-warehouse.com/showpost.php?p=1276405&postcount=74

    http://tt.tennis-warehouse.com/showpost.php?p=1276728&postcount=76

    http://tt.tennis-warehouse.com/showpost.php?p=1275957&postcount=5
     
    Last edited: Mar 15, 2007
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  2. Pro_Tour_630

    Pro_Tour_630 Legend

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    I put around 6 grams of lead at 3/9, the frame is a little better but still less stable than Stock US K90. I strung it with Gamma Professional 18g at 60lbs and it was stiff. My arms is hurting a little. I did not like the set up nor the custom job. IMO any K90 should not be strung 60 or above. I am going to try to reinstall a new bumper and few more string jobs before I give up on my adventures with the K90. Hope all goes well
     
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  3. Kevo

    Kevo Hall of Fame

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    Starting with a lighter string is the first thing I try when I want to see how a frame will behave with a lower swing weight. Head Fibergel Power works well for this. It adds just about 10g on a 90" frame. No bumper mods needed.
     
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  4. alan-n

    alan-n Professional

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    I've found the right swing weight for my tour 90 for both doubles and singles play by trimming 3" off each side of the bumper guard. Still enough mass in the head to be stable and enough maneuverability to be as quick at the net as with my 95's. The Asian version is still balanced too head heavy for my liking.
     
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  5. 888Factor

    888Factor New User

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    How did you guys trim off the sides of the bumper guard? use exacto knife? dremmel? box cutter?
     
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  6. 10sfreak

    10sfreak Semi-Pro

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    Michael Chaho, is that a calculated SW, or did you actually have it measured? 'Cause your SW is a lot lower than the measured SW I got with my UK90. As I posted in another thread, I took my racquets to a PGA Tour Superstore and had them measure some racquet parameters for me. Here are the results:
    PS85, strung with VS Gut 17 mains/Lux BB Original crosses, no overgrip: 12.8 oz., 325 SW, 64 flex
    UK90, strung with Tonic Gut 16 mains/Lux Power Rough crosses, Wilson Pro overgrip: 12.8 oz., 344 SW, 67 flex
    AK90, strung with VS Gut 17 mains/Lux Power Rough crosses, Tourna Grip II overgrip: 12.0 oz., 334 SW, 59 flex
     
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  7. Pro_Tour_630

    Pro_Tour_630 Legend

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    it is measured on a prince machine, 335 is normal but 344 is a bit high, I cant imagine the extra wilson overgrip will increase it that much. there has been reports with a wide range of tolerance coupled with accuracy of machine and type of string will result in difference in SW

    Your Asian is also high, I would check the accuracy of the machine you are using or measure them unstrung with no overgrip, let us know
     
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  8. dylo

    dylo Semi-Pro

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    can u show us some pics of the shaved bumperguard and handle (w.out the grips on of course)
     
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  9. 888Factor

    888Factor New User

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    plz explain how you shaved the bumperguard?? did you cut the side off when the bumper was off the racket? or did you do everything on the frame?
     
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  10. Pro_Tour_630

    Pro_Tour_630 Legend

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    [​IMG]

    [​IMG]


    you can use new box cutter or exacto knife but be very careful, use force but controlled force while bummper is still on frame if the stick has been strung, or if the stick is brand new you can pop off the bumper and cut the bumper on a phone book or using scissors.
     
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  11. anirut

    anirut Legend

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    MC,

    Though my stick's not the K90, but my bumper-trimmed Redondo plays great too.

    And, eh ..., yes, I did remove a tad too much weight by trimming away all the bumper. Problem solved using a 1-gram "object" spreaded from the 6th cross from one side to the other, to also act as "scratch guard".

    I haven't measured the SW yet. Once fine-tuned, I'll post the outcome in the Redondo thread.

    Just want to co-demonstrate that trimming the bumper CAN do some magic.
     
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  12. Fedace

    Fedace Banned

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    You can make it more headlight, but i was told my JCS whom does most of the pro rackets like Safin, Hewitt, Nalbandian and like, said it is impossible to lower the swingweight. that is why you buy a racket with lower enough swingweight to modify it to your liking.
     
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  13. anirut

    anirut Legend

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    Interesting ... even if we REMOVE weight from the racket?

    It's understandable that adding weight to handle/butt will make it more HL, but that adds to the SW. What we're talking here is removing weights from the racket such that it becomes more HL, WITHOUT adding weight to the handle/butt.

    Could you please check for us. Thanks.
     
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  14. ollinger

    ollinger Legend

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    It's amazing how people buy a racquet they ought to know is going to be unusable for them and butcher it into an undersized granny stick. The long Wilson thread is hilarious, with all these guys who went out and bought half a dozen K90s and now are desperate to get their hands on the asian version. Taking a K90 and paring down to a swingweight of 305....what must that play like?
     
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  15. Pro_Tour_630

    Pro_Tour_630 Legend

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    Nope JCS is WRONG.

    SW was lowered by 30 points strung and measured on the same Prince machine I used before. It is now 305 which IMO is overkill, ideally the K90 should be around 320g I have added lead at 3/9 as you can see in the photo for added stability but it still did not play well. Next I am going to Cauthenis it ;-)
     
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  16. Pro_Tour_630

    Pro_Tour_630 Legend

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    you have added nothing constructive here. The point of all this is that we can do whatever we want with the K90. We can customize the hell out of it in anyway shape or form. I can have this same "granny" stick play like a beast in 15 minutes , or I can have it go back to STOCK form in less than 15 minutes.


    Now to answer your question, at 305 it played like crap, any other questions?
     
    Last edited: May 21, 2007
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  17. Fedace

    Fedace Banned

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    Yea sure, you can scrape off 1/3 of the graphite off the head of the frame with sandpaper or grinding machine and see what happens?? Or maybe it will make the head more flexible too, maybe you will get more control while at it.;)
     
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  18. Pro_Tour_630

    Pro_Tour_630 Legend

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    no need to check I removed 15grams from 360 to 345 ?!?!?!?!?! please read my links on how I did that in the OP.
     
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  19. Pro_Tour_630

    Pro_Tour_630 Legend

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    Fedace, yeah I can make my K90 more flexible, not telling how though, not now at least

    I will give you a hint BORG
     
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  20. NoBadMojo

    NoBadMojo G.O.A.T.

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    i played my t10's w. trimmed bumpers for a few years...trimming the bumper resulted in a significant reduction in swingweight

    i think this procedure only works well with certain frames..making any frame freakishly headlight is gonna make the frame pretty lousy..i cant see doing it to a frame like the k90 which i believe is already pretty headlight in stock form
     
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  21. Pro_Tour_630

    Pro_Tour_630 Legend

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    This works well in K90 when people who use POLY/or want to concentrate lead at 3/9 which adds noticeable weight to the head, will negate the effect somewhat
     
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  22. armand

    armand Banned

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    Which BORG? This one?
    [​IMG]
    Or this one?
    [​IMG]
     
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  23. Pro_Tour_630

    Pro_Tour_630 Legend

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    well we are talking about tennis, so it must be Bjorn

    OK I will give you another hint, it is not the racket he played with, there, that is it, no more.
     
    Last edited: May 21, 2007
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  24. Fedace

    Fedace Banned

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    Why, did Bjorn chew off part of the graphite out of the head of the racket ?;)
     
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  25. NoBadMojo

    NoBadMojo G.O.A.T.

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    so you cut the weight away and then add it back??? i think people should just buy the right frame to begin with, call it a day, and learn how to use it. i've never leaded any of my regular frames ever and the t10's were the only ones i've ever modified in any way other than slapping on a leather grip, and i took weight out of them at 3 and 9 rather than add...so much for the stablity issues....i took weight away from 3 and 9 and found no loss of stability....thats what happens when you reliably hit the sweetspot.

    the pros lead because they cant find stock racquets heavy enough to play and to have their frames matched.....rec players rarely have that sort of problem.

    the k90 threads crack me up..all the preaching about how those heavier frames are more stable, have better plow thru, etc etc and now evidently they've figured out they cant handle the frame and are now importing them from Asia to be like Fed....:)
     
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  26. Pro_Tour_630

    Pro_Tour_630 Legend

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    Yeah it is called weight redistribution, you should know that by now.

    Ed, WHAT if one day I decided to use a thick Poly 16g and have been used to swinging an 18g synthetic. You of all people know that there is a difference of weight between these two strings (and don't tell me it is not normal to go from 18g synthetic to 16g poly) It is not uncommon for someone to trim 5 grams from the bumper if the difference in the above weight in strings is closer to 5grams. You are somewhat trying to keep the same SW using a heavier string, that is all.
     
    Last edited: May 21, 2007
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  27. bad_call

    bad_call Legend

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    armand - thanks for the Borg pic with the young guns. nice to see that guy again.

    btw - does shaving the racquet like that void the warranty?
     
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  28. NoBadMojo

    NoBadMojo G.O.A.T.

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    i can see how if the racquet is slightly too high in SW because of poly and you remove some of the bumper material that would perhaps wash out the increased swingweight due to the poly. frankly, you and i seem to be about the only ones observing the increased swingweight due to poly..i dont know if you came upon that by measuring or by feel, but i can feel it. Racquet Doctor I believe indicated the usual difference is about 5 points between a reg syn gut and a poly..pretty significant

    i dont remember the bumper guard of the k90 but i dont think it extends down so far, so if you remove material from it, you'll lose protection and i think the frame is already seriously headlight to begin with..making it even more so would make for a pretty lousy playing bat in my estimation, which was the point i was making
     
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  29. 888Factor

    888Factor New User

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    thanks michael chaho.....did you notice any difference in the aerodynamics as you swing in the air? made it "smoother" so to say???
     
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  30. Pro_Tour_630

    Pro_Tour_630 Legend

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    Ed, You are agreeing with me;-)

    The US K90 has a high SW to some people which is why people are flocking to the Asian, hence my thread. I can make a US K90 play like an Asian K90 with out importing. Not that they both play well. So far the K90 has not been so great. I am working on making it more flexible/comfortable.

    I am measuring the difference in string weight not going only by feel.

    Besides I think this whole K90 has not grown on me and I have not made it to work. The DNX10mid blows it away, you were right. Shall I say we Cauthenised the DNX10mid! and have not been able to do the same with the K90
     
    Last edited: May 21, 2007
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  31. Pro_Tour_630

    Pro_Tour_630 Legend

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    Of course, it was easier to swing, the stick is more HL and you have more head speed. There is less material and the stick feels very thin at top like the Stvincent PS 85 which did not have a bumper
     
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  32. fearless1

    fearless1 Rookie

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    Olli's right...start lower with a different racquet then add wt upwards. Alternatively, learn over an extended period of time to use the racquet at its stock heavier wt. There are significant advantages to playing with a heavier racquet such as K90 once you learn how to use it. K90 excels at its stock wt or HEAVIER.
     
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  33. armand

    armand Banned

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    Michael Chaho, have you attempted the 001 90? I think it would blow your sox off
     
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  34. anirut

    anirut Legend

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    In fact, I wish to thank NBMJ for the bumper trimming idea and now I have a very nice racket to play with.

    Let's see ... how many of us users here have tried trimming/shaving the bumper?
     
    #34
  35. Pro_Tour_630

    Pro_Tour_630 Legend

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    You are missing the point, this is ONLY A TEST to prove that we can make the K90 swing much lower. This is not about me learning to use a heavier racket and what not. I play with a Pro Tour that is over 400 grams. and yes I started off with the lightest PT630 I can find which is the Austrian PT630 and went up.
     
    Last edited: May 21, 2007
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  36. Pro_Tour_630

    Pro_Tour_630 Legend

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    I was the first one on the boards , back in the old boards around 2001 when everyone thought I was crazy, well they still do, cutting off inches from frames etc... . I doubt anyone who has put more frames under the knife before me on this board
     
    Last edited: May 21, 2007
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  37. NoBadMojo

    NoBadMojo G.O.A.T.

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    I think we agree on many things..we just have differing delivery systems :)

    My point is that since the k90 is too heavy for most, why not just buy something lighter rather than reinventing a racquet?..i think we both know the answer to that one :) if someone likes to tinker, by all means they should knock themselves out tho...but it's not like there arent lots of good choices out there which are more manageable......tennis is a hard enough game without always screwing around with and worrying about your gear and trying to force gear which isnt right for someone to work

    I agree...the dnx10mid is a really sweet frame. blows the k90 away in most every respect which you are confirming.
     
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  38. anirut

    anirut Legend

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    Before thee, oh master, I humble .... thanks for the idea!

    I haven't hacked a racket shorter though. Only have made it longer.
     
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  39. NoBadMojo

    NoBadMojo G.O.A.T.

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    even tho i have been out trumped, i would like to acknowledge and say you're welcome anirut :) i sure didnt invent this idea...people have been doing it for many years

    there are only certain frames where i think trimming the bumpers is a good thing to try..the k90 isnt one of them. michael seems to confirm this
     
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  40. Pro_Tour_630

    Pro_Tour_630 Legend

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    I was one of the first people on this board to play with the SRD tour 90's Which were nice. Not sure how much better the 001 90 would be. It is stiffer then maybe not for me. Those srd tour 90 were very flexible.
     
    Last edited: May 21, 2007
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  41. fearless1

    fearless1 Rookie

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    lol...

    Why couldn't you just postulate that removing pieces of a racquet would make it swing lighter without having to actually test it to prove it?? Me personally, I know I could use a CAD machine or precision driller to carefully lighten the frame without weakening it much if at all. But why bother to even test this to begin with?...one of the points you are missing.
     
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  42. Pro_Tour_630

    Pro_Tour_630 Legend

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    I agree based upon my experience but who knows what someone else might like, they might like an extreme HL unstable K90
     
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  43. Pro_Tour_630

    Pro_Tour_630 Legend

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    First there are many people on this board who are not as smart as you and think you can not lower SW as you have seen on this thread by Fedace and his JCS crew,

    And second, how would I know how it will play like? Were are testing frames out, tinkering with them and see how they REACT! If it is a bother for you it is not for others, we have been doing this for many years. Seems like you go around wanting people to play/adapt to a heavy frame like the K90, all the power to you.

    Seems like you added some of your own and did not disagree with some of the suggestions,

     
    Last edited: May 21, 2007
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  44. armand

    armand Banned

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    Then why are you fooling around with the [k]Tour 90:confused::confused:
     
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  45. Pro_Tour_630

    Pro_Tour_630 Legend

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    Is it a crime to fool around with another stick? even if on paper it might be stiffer? besides, I am trying to make the K90 play more flexible which is why I like the DNX10mid. I might give the 001 90 a try but not now I have way too many setups to test first.


    EVERYONE, I HAVE MANY FRAMES OVER 500 AT ONE POINT, THAT I TEST. I AM NOT MARRIED TO ANY OF THEM. WHAT I DO WITH THEM IS NONE OF YOUR BUSINESS, IT IS A HOBBY FOR ME. I ENJOY WAISTING MY TIME TINCKERING WITH FRAMES/STRINGS. I ENJOY THE PROCESS OF TESTING DIFFERENT FRAMES WITH DIFFERENT SET UPS? IS THAT A CRIME?
     
    Last edited: May 21, 2007
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  46. alan-n

    alan-n Professional

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    Curios to know if anyone here tried polarizing the weight distribution of their tour 90's (removing leather grip, replace with lighter synthetic + lead at the end of handle and/or slight trimming of bumper guard and placing lead at tip bringing the overall weight back to stock or heavier, but keeping the balance the same)? I've been playing this setup with my tour 90's the first day I've played with them which goes back to the original tour 90. Seems to make for a whippier stick with any racquet I do this to, and I do this to just about all the racquets I own.
     
    #46
  47. BreakPoint

    BreakPoint Bionic Poster

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    And how exactly is that any of your business? :confused:

    I was speaking directly to Michael Chaho, not you. He's the one that seems like he would be interested in obtaining an Asian K90. You've already stated that you don't like the K90, Asian or otherwise, so how does my post have any relevance to you whatsoever? :confused:
     
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  48. Pro_Tour_630

    Pro_Tour_630 Legend

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    I have, from what I recall it still did not feel right to me. I don't know what it is but the Wilson 90's have not warmed up to me. I liked the PS 6.0 85 and the original PS95.

    Like I said I will attempt to use John Cauthens method of lead above the handle to the K90. I did not as of now because I only did Johns stringing method, it did not pan out and I got discouraged with the K90 when the DNX 10 mid worked so well, it is on the back burner though.
     
    Last edited: May 22, 2007
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  49. morten

    morten Hall of Fame

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    i have trimmed bumper, made it better, but still not right, Wilson, just give us a braidet 6.0 90 and get it over with..
     
    #49
  50. grass_hopper

    grass_hopper Professional

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    I hope wilson do read this thread and come up with custom groumets for k90, this is how after market stuff are created.
     
    #50

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