Overgrip thickness confusion

Discussion in 'Other Equipment' started by misty, Jul 2, 2013.

  1. misty

    misty New User

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    According to the maths I learned at school, the circumference of a circle is 2π times its radius. So if I add an overgrip of thickness 0.6mm to the handle of my racket, it should increase the circumference of the handle by approximately 0.6 x 2 x 3.1 = 3.72mm, which is roughly 1.2 grip sizes.

    However, it is commonly stated that an overgrip adds around 0.5 size (e.g. see Increasing Grip Size).

    Can someone explain where my reasoning is going wrong?
     
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  2. OKUSA

    OKUSA Hall of Fame

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    I believe you have the wrong units, there is no way your handle has a 3.1 mm radius, cm yes not mm

    plus a racquet handle is not a perfect circle, so you would need calculus to figure it out possibly
     
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  3. misty

    misty New User

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    The "3.1" is an approximation to π (pi = 3.1415926...), and "0.6" is the increase in the radius measured in mm.
     
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  4. OKUSA

    OKUSA Hall of Fame

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    but your units on the radius of the handle is in cm

    so in reality you have 2 x 3.14 x 3.16 cm instead of 2 x 3.14 x 3.10 cm. the addition of a 0.6 mm is 0.06 cm
     
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  5. misty

    misty New User

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    I'm not using the actual radius in my calculation. I'm talking about the increase in the circumference of the handle caused by an increase in the radius.

    And I'm not using cm in the calculation either - I'm using mm and "grip sizes", where:
    1 grip size = 1/8 inch = 3.175 mm​

    Your calculation (using an actual radius of 3.10cm as an example) shows an increase in circumference of:
    2 x 3.14 x 3.16 - 2 x 3.14 x 3.10 = 0.38cm​
    This is equivalent to an increase in grip size of 0.38 x 10 / 3.175 = 1.2 grip sizes.

    That is my problem: the stated thickness of overgrips seems to add a whole grip size, not the usually stated 1/2 grip size.
     
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  6. OKUSA

    OKUSA Hall of Fame

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    There are other factors that contribute to the inflated grip size. First, it's not a circle and second you stretch the overgrip as you put it on making the thickness smaller
     
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  7. misty

    misty New User

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    Interesting points, but ...

    Handle shape

    An octagon might be a better approximation than a circle. A regular octagon with sides of length A has perimeter of 8A and a "diameter" (distance between opposite sides) of (1 + sqrt (2)).A = 2.414. So the ratio of its perimeter to its diameter is 8 / 2.414 = 3.31 (this is actually more than the 3.14 ratio for a circle).

    Adding a 0.6mm overgrip to a regular octagonal handle would add 2 x 3.31 x 0.6 = 4.0mm to the perimeter. That's equivalent to 1.3 grip sizes.

    Stretch

    An overgrip probably stretches by at most 5% in length when applied, so the thickness is probably only reduced by 5% or less.

    Measurement

    What actually happens in practice is the best way to test theory, so I tried measuring a handle before and after applying a Tourna overgrip:
    Without overgrip: 110.5mm​
    With grip: 114.5​
    So the perimeter was increased by 114.5 - 110.5 = 4.0mm = 1.3 grip sizes, agreeing exactly with the theory.

    I simply wrapped a tape measure round the handle to measure it, so I could only measure to the nearest 0.5mm - but it's accurate enough to show that the increase is much greater than the usually stated 0.5 grip size.

    Has anyone else actually measured how much an overgrip adds to the grip size?
     
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  8. Blitzball

    Blitzball Semi-Pro

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    Does it really matter? Put an overgrip on your racquet, hold it, take it out for a few hits, and determine whether the grip is too thick or if you need a bigger/smaller sized grip. Besides, there are so many overgrips that vary in thickness that it's hard to figure out exactly how much the grip size increases.
     
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  9. misty

    misty New User

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    It probably doesn't matter much when choosing an overgrip - there are more important characteristics to consider. But my concern was how to increase grip size.

    According to the standard method of measuring hand size, I need a grip size 9 (5 1/8 inches)! If I ignore the advice to leave an index-finger gap between my finger tips and palm, and just try avoid my finger tips touching my palm, I can get away with a size 5 grip (4 5/8 inches). Unfortunately there are very few grip 5 rackets available in the UK - even grip 4 rackets are not widely stocked.

    So I was looking for ways to increase grip size by 1 or 2 sizes. According to the TW article on Increasing grip size, an overgrip would only add 1/2 size and I would have to use a heat-shrink sleeve to add a full grip size. But I couldn't understand the reasoning in the article - hence this post.
     
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  10. Attila_the_gorilla

    Attila_the_gorilla Professional

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    The 3.1 cm you are using is not the radius but the diameter.
    So the actual difference in circumference will be:

    2x(15.8-15.5) x pi ----> 0.6x3.14=1.9 mm

    Add a little extra for the shape of the handle not really a circle.
     
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  11. Attila_the_gorilla

    Attila_the_gorilla Professional

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    Ooops I added the grip thickness to the diameter, not the radius, so you're actually right. My bad.

    2x(16.1-15.5) x pi ----> 1.2x3.14=3.8 mm

    So yeah, adding a bit because of the shape, end up with about 4mm difference.
     
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  12. misty

    misty New User

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    Thanks Attila - it's good to know that someone agrees with my reasoning :)
     
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  13. Attila_the_gorilla

    Attila_the_gorilla Professional

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    Yeah it's a bit disappointing that even websites with expert advice make that sort of mistake. All the more reason to err on the side of caution and buy one grip size smaller, maybe even two sizes, although it depends on brand as well, and what type of grip the racket comes with.
     
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  14. smalahove

    smalahove Semi-Pro

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    My somewhat limited experience with this, is that the overgrips I use on my size 2 rackets increases the grip size to a size 3 (ca). I have only Prince rackets, but the numbers were identical.
     
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  15. corners

    corners Legend

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    Great work misty! I've been measuring a bunch of handles, with and without grips, to figure out exactly how much larger Yonex handles are than other brands. I was also finding that an over grip increased size more than believed but didn't have the courage to contradict the old "1/2 size" CW. :)

    Sounds like you've got your handle-expanding needs taken care of, but this stuff is great for increasing grip size with very little weight.
     
    Last edited: Mar 11, 2014
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  16. ChicagoJack

    ChicagoJack Hall of Fame

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    Cool :) I think misty might be onto something, and if it's true, we might have to re-write some of the prevailing wisdom about grip sizes. But just thinking out loud here:

    1. There is the thickness of the OG, then there is the thickness of the OG when it is stretched (the 5% thinner idea sounds reasonable), but don't you have to figure in the overlap somehow? Andy Murray prefers what is called "flat wrap". His overgrips don't overlap at all. But for most everybody else, the OG is overlapping by 1/4 to 1/2 of the total width, so it's twice as thick in those spots. Joe wraps with a 1/4 overlap, Pete wraps with half the width overlapping. Pete's grip will feel bigger, so I don't know how you account for this variation in a math equation designed to predict such things?

    2. I've handled the heat shrink sleeves which are manufactured and marketed as building the grip up exactly 1 size. I dunno, just going by feel and look, very unscientifically speaking here, these sure seem thicker than one or even two layers of overgrip. Misty's theory poses the idea that a 0.60mm OG adds more than one grip size (1.3 sizes actually) If I had a nice set of digital calipers, I'd look at the thickness of those sleeves as a baseline reference/confirmation point. It's plausible that the heat shrink sleeves don't really add exactly 1 grip size (1/8"). But until proven otherwise, that's probably a good baseline and should prove useful for figuring this out in a non-math, reverse engineering sort of way. I used to bring my drafting tools to geometry class, which drove my teacher crazy, but taking measurements often helped me to understand and confirm equations, theories, and theorems. I find myself wanting to do the same thing here.

    -J
     
    Last edited: Mar 12, 2014
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  17. Shroud

    Shroud Hall of Fame

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    My experience is similar to yours. I buy 4 1/2" sticks, replace the leather grip, add a bit of thin cardboard to 4 bevels, and then 3 ogs. brings the grip to a bit over 5 1/4". factor in the cardboard and the fact that the replacement grip is a bit larger than the stock grip, I think those ogs are adding around one size.

    I think it was mentioned but how you wrap makes a big difference.
     
    #17
  18. corners

    corners Legend

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    I just did Andy's flat wrap and it added a bit more than 1/8" to the circumference (wilson pro), so slightly more than 1 full size. Misty's math checks out. And his experiment to confirm his calculations (measuring!) has been replicated by at least one other player (me). This protocol is easily replicated by others who remain skeptical.

    As to heat sleeves, don't know. Am waiting on 1/2 size sleeve now.

    Hey Jack, I see gut/ZX in your sig. How's that going? Have you written about it anywhere on the boards. If not, care to write up a review?
     
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  19. ChicagoJack

    ChicagoJack Hall of Fame

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    This is starting to look more and more like breaking news, two confirmations from corners are pretty good confirmations in my book. I'm officially a believer. But if there's a skeptic out there who needs convincing, I'm thinking a comparison of the thickness of a heat shrink sleeve with digital calipers would still be required. The tape measure method of confirmation is certainly valuable, but seems tough to be super accurate with, because tape it self has thickness, and I wonder if that's a factor.

    Yes, I've been using Gut/ZX now and love it. I strung up all nine of my identical P1's on the same day with all of the string combos I've ever wondered about, just to settle my mind about it once and for all. (It's one of the reasons an amateur player like myself wanted 9 identical racquets lol). This was a few weeks before Nationals so the timing wasn't right for a big change, and I went with my typical gut poly I was grooved with. But as I continued demoing, I became more accustomed to the lower trajectory of Gut/Zx and simply love the impact feel. I'm also happy with a full bed of the stuff for rainy conditions, so I've no need for poly whatsoever. (very happy about that) I'm happy to update my old demo/search thread in the string section when I get a chance.

    -J
     
    Last edited: Mar 13, 2014
    #19
  20. corners

    corners Legend

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    I'm using a long strip of paper for measuring circumference/perimeter - wrapping around, marking, laying out along my ruler. Paper is essentially without thickness, but I don't think it matters. I can't find my garment tape, which is what I would usually use. And I can't find my calipers, either! I do have a 1/2 size sleeve on the way and will do what measurements I can.

    Of course, most overgrips compress in the hand more than replacements or sleeves, so increasing one size with something soft and squishy like Wilson Pro is not the same as increasing one size with a plastic sleeve. But I do think misty's work is breaking news, for sure.

    Awesome, Jack! I really had my heart set on gut/ZX when the TWU numbers for ZX came out. Just seemed to be the perfect cross for my purposes. Then a handful of reviews hit the boards, none of them particularly positive. My plans for string tests last summer got obliterated by other time demands and I was just yesterday starting to think about which strings to order for the spring. I was leaning strongly toward getting some ZX but wasn't quite sure. Now I am. Thanks.

    Yeah, definitely update your old thread when you get around to it. Are you pre-stretching the ZX ala Trav's extreme protocol?
     
    #20
  21. HeeK_ILRF

    HeeK_ILRF New User

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    Can anyone tell me if wilson makes "sensation" ovgrips? Or we r talkin only about strings?
    Thx
     
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  22. Shroud

    Shroud Hall of Fame

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    Here are some picts from some grip work I did today. I added 3 og to the shock tape replacement grip:
    [​IMG]
    [​IMG]
    [​IMG]

    The last 2 grips were brand new Gamma Supreme. The first one was a used Gamma Grip 2 I believe

    Final:

    [​IMG]

    Given variances in measurement technique, it does look like one OG adds roughly 1 grip size.
     
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