Preventing graphite sink-in

I am not sure if you all have faced this problem; so at higher tensions in my experience, I have seen a lot of racquets having the graphite sunk in at the area where the bottom 5 to 10 grommet areas are. My first experience with this begun with a JP coded AT900P I own which was strung with BG66 Sharp at 28lbs. Even though it was nowhere near the 30lbs+ of tension that I currently use, the graphite where bottom grommets 5 and 6 have sunk in very significantly and worries me. This seems to be an inevitable case for almost all of the racquets (plus a little bit from 7 to 12) I have ever seen. Although the only racquet that I know which is designed with that area strong enough to withstand such deformation and yet can be strung to very high tensions without issues is the Yonex MP100. Even though the lower ended Muscle Powers also have this frame shape at the bottom, I have no experience and would not expect them to have the properties of the more expensive and noticeably tougher MP100. My old Ti-10s which are strung at 24lbs max that I used to use when I started badminton also have a little bit of that string marking on the paint around that area even though there was no sink-in.

Here are some pictures of the sink-in that I am referring to:



I have since bought the Yonex [six and two holes] Continuous grommets and installed it at all of my Yonex racquets to prevent such graphite-sinking case from happening again. However, as good as the grommets seem, the bummer is that they only fit the specific Yonex racquets that they are designed for. One racquet that I would really like to invest in is the Li Ning N90, which like all Li Ning racquets, do not have any "wide" [aka two holes continuous] grommets even near the T-joint at all. Even though the N90 is designed from and based on the AT700 so thus has almost the exact same shape, I have tried and discovered that the six and two holes continuous grommets from Yonex for the AT700 do not fit the N90 tight enough for a good usable fit

Even though I have heard of positive reviews about Li Ning racquets having very tough single hole grommets that can withstand a lot of pressure from tightly strung strings, I still doubt the so-called invincibility of the grommets. For one, it is not physically possible for these Li Ning grommets to remain totally unscratched throughout the racquet's entire lifetime. The difference between the single hole grommets and the six and two point continuous grommets is that the later ones spread the pressure from the string laying on top of them very evenly thus distributing and minimising the pressure from the string acting on the graphite while also acting as a protective barrier between the string and the graphite. For the single hole grommets, it is always possible for the string to cut through the grommet or flatten it and touch the graphite.

One good example is the Panda Power racquets I own. Even though in all reviews they have been identified as very strong and can be strung to very high tensions (I use 31-32lbs on my Trinity 2 for one), the last time I checked before restringing them I saw undoubtedly string marking on the paint and perhaps even the graphite at the area where I mentioned. The good thing about this is, since the Panda Power racquets are considerably cheap for a "professional grade" racquet for my usage, I am able to see this as a "normal" thing and if the racquet does break then I would replace it.

However, for a Li Ning racquet, which costs almost twice the retail value of the PP racquets, I see this as a very big disadvantage of the LN racquet design. I could probably replace the grommets at that area every time I restring my N90, but with the grommet that I can buy from retail shops, are they really as good as the LN ones? I definitely think that one day when I am restringing my N90 with the newly installed grommets something may go wrong and the single hole grommets may be cut and the string will end up sinking onto the graphite. I certainly would not want to expect my N90 to have a dent in the graphite and that the graphite will inevitably crack one day. I am not sponsored to use LN racquets and replacing a N90 messed up by this is definitely a good thing to do or plan for

Since the grommets for AT700 do not fit the N90, I am actually reluctant in investing in LN racquets even though I really like the fact that the N90 plays very similar to my all time favourite AT700. I have since then read on experiences of stringers putting trimmed used grip tape around the grommet are in between the single hole grommets for the string to rest upon. I have actually seen stringers doing this to the older Yonex racquets which do not come with the wide fitting grommet at the T-joint area.

This actually sounds like a good idea to me but to cut the leather grips into such small and tight fitting shapes in between two grommets on a racquet is no easy feat. And I am aware that these barriers made from these used grips can still fall off when you remove the string off the racquet, unlike the Yonex grommets.

I would like to hear your experiences with protecting racquets from string sink in on single hole grommets. Perhaps there is a method out there which I have not heard of that may actually work?


By the way, the photos of the AT900P I have shown are actually Lee Chong Wei's which were taken by stringers (circa last year, before the AT900PLC came out during WC2010 if I am not mistaken). Here are more pictures of the same racquets for your viewing pleasure:

 

Mark, unfortunately the HiQua string protector/grommet pad that you're recommending are not as durable as the Yonex continuous grommets:

There is still a chance that the string may come into contact with the graphite in between the grommets and cause a cut. The most fundamental difference between these HiQua grommet pads and the Yonex continuous grommets is that the Yonex ones spread the pressure load from the string evenly across a flat surface while the HiQua ones only lift the string up at the middle part. In fact, the HiQua ones are not made of hard plastic used in grommets like the Yonex ones.

 

Kwun, for my own AT900P JP, I bought it brand new but pre-strung from a player who had it originally at 28lbs with BG66 Sharp. It was after I cut the strings then I noticed the sink-in and have not have it restrung. So you can pretty much say that the damage was done on the first string job.

Do you mean silicone tubing shaped to look like the stock single hole grommets?

On another hand, I was thinking if there is a way for me to "beef up" the structure of the stock grommets and have them spread the pressure load evenly above and away from the graphite. The bummer is that I have rarely read or heard of reviews of people stringing and using Li Ning racquets at my personal likings (31lbs and above) mostly due the the expensive investment of the racquets, so it is hard for me to analyse and plan my next move.

I would not want to go ahead, string one LN N90 at 32lbs with the stock grommets and play as usual until the string breaks then make the observation; that would be an expensive learning process. Compared to a old colour Yonex AT700, which costs slightly more than the LN N90, at least I have a method of preventing such graphite sink-in with the Yonex continuous grommets so in the end I am pretty much making a blind gamble with the LN N90.

If only I were sponsored and given free LN racquets to use then I would not be having such worries

 

Twobeer, I wish I am as rich as you, such that I am able to proceed with the experiment I talked about above

But like I said, I am basing my observations on scientific grounds. The single hole grommets really are not able to distribute the pressure from the string as evenly and also barrier the string away from touching the graphite as effectively as continuous grommets.

However, from your statement, it would seem to me that the LN N90 [and probably most of the other LN racquets] are made with very good quality graphite and paint which enables it to withstand very high tensions? This reminds me of the Panda Power racquets especially the "Pro" models, although like I said I would be able to replace one of these PP racquets much easier (on the money side i.e.) compared to replacing a LN racquet. In fact I have now kept that AT900P JP of mine away in storage due to the sink in and fear that it may give away anytime in the future.

LN providing the new racquets with a pack of new grommets is a good thing, but I must have missed that since the N90 I bought is a old logo model which did not come with that.

Thus, I would like to find a way to prevent the string from even coming close to the graphite in between the two grommets. There could be a method of strengthening the top of the grommet that comes into contact with the string, and I would like to find out. It is always better to mitigate and remove the hazard than letting the hazard come at you and then apply engineering control. In this case having the correct grommet compared to letting the frame's graphite handle the pressure.

 

Hey, Jerby. What you described is actually the opposite for the AC416L3 with the LN N90. The continuous grommets are actually "over-fitting" the grommets on the N90 such that rather than not being able to reach all the holes as you described, there are actually some gaps between the bottom of the long grommets and the graphite underneath. I stuck some PU from some used grips in between the space but overall it still looks uneven and thus is not a perfect fit like with AT700.

On another hand I have a friend who recently bought a pack of AC416W2 but not the AC416L4 so he cut them in the middle to fit the bottom holes from 7 to 12. It seems to be functional but visually what you can see is a gap in the middle of the continuous grommet. I could probably try that but personally I would prefer a more visually appealing effect

 

Great idea! I had thought about that sometime ago, but could never find it sold in bulk, and MBS has it but in the AT700/500 set which includes all the extra rounded tip ones too. Perhaps Winston Chan would know..

 

My understanding with materials is that IMHO you cannot have both strength and flexibility at the same time with graphite. Namely, the harder (i.e. able to withstand pressure from string contact) a graphite structure is, in this case the frame, the more brittle the whole thing will become especially when confronted with hard impacts. The badminton racquet frame should always have a little bit of flexibility as during hard shuttle impacts a little off centre, the frame always has a small tendency to warp a little and a very hard frame can break easily.

Yonex used to make the MP100 with that hard [Ultra High Modulus] graphite frame that I mentioned. With the MP100 that I own I have never seen any signs of string cut through even at very high tensions. But then remember how a lot of people (especially the not-so-professionals, pardon me) were complaining how brittle and fragile the MP100's frame is with mishits? There should be a balance of the amount of hardness that you can manufacture the racquet frames. However if you do insist that it is the utmost important and then have the hard graphite be integrated at precisely and exactly where it the string should come into contact with the frame the most, then I certainly would not want to think about the cost of R&D that may incur and how much I would have to pay as a customer just to purchase one of these racquets. I am not sponsored by any company anyway

So personally, I do not agree with your comment on how grommets are a poor man's solution because in fact, they are the smart man's solution for the problem we are talking about here. Come to think of it, how many racquets that do have a lot of string to frame contact can we see in the market today, even from Li-Ning? Like I said, I do not think that making either a frame very hard but overall brittle or a frame with exactly the right amount of hardness where you think it truly matters but overall costs a lot are the smart choices to make.

The person whom I bought my N90 from must have forgotten to pack it in for me. Could have been some confusion as during the time I also ordered some packs of AC416L with the order.. The N90 I have is genuine anyway

 

Twobeer, you're getting ahead of yourself. Of course the original function of grommets is to protect the string from sharp edges of the holes, but I am now referring to how strong-tipped grommets can also help to keep the string from touching the graphite in between.

I almost have a feeling that you're only just trying to get me to spend and buy LN racquets while avoiding YY racquets due to your own personal preference. Please stay on topic. Sh*t [string cutting through grommet, coming into contact and cutting the graphite] can happen to all racquets which are not protected properly so I am trying to find a way to remove that hazard risk rather than leave it to the strength of the graphite to be the decider as you would recommend. The stock grommets are really not enough as you suggest.