Monday, 14 July 2008

Badminton Rackets and Tension Explained

Most badminton players are familiar with the notion that lower racket string tensions give more power, and that higher racket string tensions give more control. The general idea is that lower tension strings stretch more on impact and store more energy. When the shuttle rebounds from the racket head, more of this energy is returned, resulting in increased shuttle speed. The idea that higher string tensions provide extra control is a bit more complicated to explain.

If we take control to mean the ability to place the shuttle consistently at an intended position, then how would this extra tension help to achieve this? Many badminton players report that having a badminton racket strung at high tension gives the feeling of more "bite" into the shuttle, which provides more control over the shuttle. The theory is that the strings will cut deeper into the base of the shuttle, especially on slice shots, giving more control. Many of the string manufacturers produce thinner gauge strings, and they then market them by claiming they offer more control as they help to bite into the shuttle base more, which is the same theory as the high tension, both are concerned with this "bite". Thus, if we have high tension and thin strings we should achieve the most control because of the extra "bite" factor.

Now this theory has been tested at the university of Sheffield in the UK. The test was conducted on tennis rackets, and the amount of top spin produced with different string tensions. The same basic principles must also apply to slice shots in badminton rackets, they are doing virtually the same thing. The results showed that string tension, or string type, had no effect on the amount of spin produced. It was found that all stringbeds are sufficiently "rough" to produce the maximum amount of spin.

This scientific evidence goes against what most of us badminton players think. I must admit that i always assumed that high tension and thin gauge strings would allow me to produce more spin on the shuttlecock and create more slice. The answer is that it makes no difference at all. So the next time you read about Yonex and Ashaway claiming that their latest thin gauge string will give you more control, you now know that this is not the case.

However, many players still feel that they can produce more spin or slice on the shuttle at higher tensions. There may well be other factors that can explain this. The same study mentioned earlier was also applied to the amount of spin produced by two identical rackets strung at different tensions, with the exact amount of racket head speed on contact. The results again showed no difference in the amount of spin produced.

However, tight strings produce less velocity compared to looser strings,(remember the rebound effect of lower tensions). This would result in the shuttle landing shorter in the court. So if two identical badminton rackets were used, but strung at different tensions, with the exact same head speed on impact, the one with the higher tension would send the shuttle shorter into the court. To make up for this, the player with the high tension strings may well swing faster, thus creating more spin. Now in this case, it is not the tension that has created the extra spin, but the player. It is the players response to tighter strings that produces more spin, not the tension itself.

If string tension does not have any effect on spin, then it cannot have any influence on added control through spin, ie you cannot slice the shuttle more with high tension strings assuming the racket head speed is the same for the shot. But there are other variables that do vary with string tension. The first is string movement. You would assume that at lower tensions, the strings will deform and move more when you play a heavy slice shot. The strings would move in a sideways direction. This has been tested and it does happen. Tighter strings do not move as much on impact with the shuttle.

But does this string movement have any affect on control? As the shuttle hits the strings they will deform in a sideways direction depending on the type of slice. The strings, however, stay in this deformed state even when the shuttle has left the racket. They have not recovered back to their original position. You can see this in action if you play a slice shot and then look at how the strings in your badminton racket have moved to one side. If the strings were able to move and then retain their original position before the shuttle had left the racket face, then in theory they would produce more slice or spin on the shuttle, but they don't, hence the findings that spin is independent of tension.

The amount of string movement will affect the impact because it will influence the location that the shuttle leaves the badminton racquet. This movement will also affect the speed and angle that the shuttle leaves the racket, and therefore, where the shuttle will land on court. This will result in inconsistency, and hence less control over where the shuttle will land. The amount of string movement also depends on the speed of the swing, where exactly the shuttle is hit on the racket face, and the position of the strings on impact. If you have previously hit a heavy slice shot, the strings will be deformed, and if you hit another slice shot immediatetly after this, then you may find that the shuttle is only in contact with one string on impact, rather than two or three. The result is lower tension results in less consistency, and hence, less control.

Another factor to be considered is dwell time, ie, how long the shuttle is in contact with the strings. Scientific evidence has shown that contact time on the strings is higher with lower string tension, as you would expect. The shuttle also moves further across the stringbed at lower tensions. If we take the example of a player playing a slice shot, then the racket strings will brush across the base of the shuttle. The probability that this slice shot is performed correctly is increased if the distance that the shuttle travels across the stringbed is minimised. So tighter strings will increase the probability of a successful slice shot.

Another impact of dwell time on control can be seen with racket head movement. The longer the shuttle is in contact with the racket head, then the more the racket head can move. If you don't hit the shuttle in the sweet spot, then the racket head will rotate and twist, known as torque. The longer the shuttle is in contact with the head when this happens, the more head rotation will occur, which will result in larger errors in your shot precision. Higher string tensions help to eliminate this unwanted effect.

To summarise all this up, string tension and string type has no effect on the amount of slice you can impart on the shuttle. However, tension does affect dwell time, string movement, and contact distance. Stringing your badminton racket at higher tensions makes your shots more consistent, which will add to control. Hope this little science lesson has helped you. It has certainly opened my eyes to a few things that i didn't know before.

12 comments:

Anonymous said...

What a load of bollocks you are talking!

Andrew said...

What a stupid comment, left on 17th May 2009. This is a really interesting, scientific, informative article!

Anonymous said...

agreed. well done. but as a player i feel a lower tension gives the shuttle too much bounce at the net and hence less control:P

Anonymous said...

Awesome, this article has helped a lot. Thanks!

rosell said...

correct! this has been a pretty good blog.. specially for beginners.

Anonymous said...

Quite brilliant, helped a lot with my physics homework.

Anonymous said...

Contains lot of information. Thanks

Anonymous said...

First it was RACKET and the it was RACQUET. Get your English right mate. Bloody yanks.

antony said...

Hehe, you have to cater for all languages.

Vance said...

that's good information. i broke my strings, so this article is very timely. thanks.

Anonymous said...

Use your mature word on discussion. Be like a real human kind. Thank's PEACE ...

Anonymous said...

Very informative article. Tq.