*** Beam width & Stiffness: Power, Comfort and Control ***

anirut

Legend
Was just wondering ...

Say we have two rackets, R1 and R2, of the equal headsize, weight, balance and swingweight, and strung with same string type and tension.

Both have box beam of equal x:y ratio:

- R1 has 18 mm beamwidth, and 66 stiffness
- R2 has 22 mm beamwidth, and 63 stiffness

Which one will be more powerful? Which one will be more comfy? Which one will be better with control?

Let's discuss ...
 
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BC1

Professional
My guess would be:
Powerful: R1 (because of the higher stiffness)
Comfort: R2 (because of the larger beam and more flex)
Control would be equal
 

WhiteStripes

Semi-Pro
Stiffness trumps the beam width, especially when the stiffness is pretty wide as it is in this case. So everything else being equal (strings, head size, etc.), I'd venture to say the stiffer racquet will be more powerful, and the more flexy one will be more comfortable, regardless of the beam width. Control I think would depend on the player, some prefer very flexy sticks, others like stiff racquets. I would think other factors like head size, string pattern, and type of strings/tension would probably have a bigger impact on control than beam width and stiffness.
 

anirut

Legend
I think the R2 with 58 stiffness would be too obvious, let's change that to 63.

I'm editing the info. Sorry guys.
 

haerdalis

Hall of Fame
Weight and stiffness are the most important specs when it comes to power. Beam width and headsize effect depth of shot more than power IMO.
 

spacediver

Hall of Fame
can somoene explain what beam width actually means in terms of racquet performance? I've never been able to get a clear answer.
 

anirut

Legend
A thicker beam of same material strength normally has better ability to withstand bending and thus return the energy back to the ball better, making it more powerful.

Just take a look at the ultra light granny sticks -- very thick beams -- to compensate for the loss of weight which translates to power.

Not a good scientific explanation, but that's the idea.

If I'm wrong, feel free to correct me. Thanks in advance.
 

Gee

Hall of Fame
According to USRSA they calculate the Power Index with the following formula:
Power index = (length index * stiffness index * headsize * swingweight index) / 1000
Beam thickness contributes to the stiffness of the frame. So the thinner frame (R1) must be built with stiffer material.
 

anirut

Legend
Well, the reason I'm asking is because the original Black Ace is very stiff compared to the Redondo, but it's beamwidth is only like 16 mm while the Redondo's 19 mm.

The original BA, inspite of being stiffer and with open pattern and heavier, is less powerful and less comfy than the Redondo. Control-wise it's very good though.

On this forum, we have already dicussed a great deal about swingweight. I think we should discuss more about the relationship between beamwidth and stiffness too.

Any more inputs?
 

Don't Let It Bounce

Hall of Fame
As posted above, making the beam thicker is merely one way to increase stiffness. It would be interesting if someone could feel and describe a difference between stiffness achieved by beam thickness, stiffness achieved by stiffer materials, stiffness achieved by layup (weaving or crossing fibers in adjacent layers, or having more layers), and stiffness achieved by frame geometry, but all I've ever felt at contact was plain ol' stiffness.

I do have a slight preference these days for thinner beams, but that seems like just a non-performance-related quirk of enjoying 'the feel of slicing through the air'.
 

corners

Legend
Weight and stiffness are the most important specs when it comes to power. Beam width and headsize effect depth of shot more than power IMO.
Static weight has little effect on power potential (inherent power or pop), swingweight is the spec that corresponds the most to power potential in the center of the stringbed, by a wide margin, then stiffness, then headsize.
 

corners

Legend
According to USRSA they calculate the Power Index with the following formula:
Power index = (length index * stiffness index * headsize * swingweight index) / 1000
Beam thickness contributes to the stiffness of the frame. So the thinner frame (R1) must be built with stiffer material.
Their power index is not very useful. On that site they mention that the holy grail, in terms of quantifying a racquet's inherent power (power potential or ACOR) would be to actually test the bounce of the racquet at a variety of impact locations. Since that was written this has been done, here:

http://twu.tennis-warehouse.com/learning_center/contours.php

An article on how different specs influence real-world, as opposed to theoretical, Power Potential by the TW Professor (also the head of USRSA) is here:

http://twu.tennis-warehouse.com/learning_center/specsandspeed.php

As far as beam width vs. stiffness, TW Professor recently wrote on the forum that a variety of things can influence the stiffness spec as measured on an RDC, including how soft the handle is. So in some cases we may be comparing apples to oranges when we think both are apples.

Travlerajm has written some good stuff about beam width and stiffness on these boards; a search for that would be fruitful. If I recall, he said that narrow beams are always less stiff than their RDC number would indicate. This makes sense: we know that manufacturers can make 17mm beams with 70 RDC, so what's the point of making 24mm beams with 70 RDC?

Well, one point would be to increase the stiffness torsionally. The RDC only measures stiffness in one dimension - perpendicular to the stringbed, but it doesn't tell you much about how stiff the frame is in response to off-center hits. My guess is that - if you have two 100-inch frames, each with identical specs but one being 17mm and the other being 24mm - they will have similar power in the center of the stringbed, but the 24mm will have better power on off-center hits. (They both have the same twistweight, so this would be down only to torsional stiffness.)

Think of racquets with variable beams. Usually the thicker/stiffer parts are in the head and the thinner/flexible bit is the throat.

I recall reading a post by the owner of Vantage where he said they test stiffness in four different locations, or four different kinds of stiffness. This would be a nice thing for the Professor to test in his spare time.

Would be nice if Travlerajm, TW Professor and Vantage guy would chime in.
 
I think the most important thing to keep in mind is that dynamic stiffness does not always correlate closely with static stiffness.

The dynamic stiffness is what you feel when you hit the ball, and it`s also what determines the power-to-spin ratio off the stringbed. Higher dynamic stiffness gives more power, less spin, and more directional accuracy.

If R1 and R2 have the same head shape, mass, balance, SW, and static stiffness, it does not necessarily mean that the dynamic stiffness will be the same. Comparing beam width is less important than knowing where the mass is distributed.

R1 and R2 can have the same mass, balance, and SW, but still have very different mass distributions. The frame with more mass concentrated near the balance point will have a higher dynamic stiffness.

If this is not clear, consider that if you start with a lightweight platform frame, there are infinite possible ways to add mass to reach a given spec. Say for R1, you add 10g of hoop mass at 10 and 2, and then counterbalance in the handle to reach your final spec. Then say you for R2, you start with the same platform, but add 15g at 3 and 9 to reach the same final SW as R1, and then counterbalance in the handle to match wt and balance of R1.

In the above example, R1 will play much stiffer than R2 (assuming that the counterweight is more than the mass added to the hoop). This is because R1 requires a heavier counterweight (5g more) than R2, and the counterweight for R1 will be higher on the handle (closer to the balance pt), thereby having a greater effect on the dynamic stiffness.
 
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Limpinhitter

G.O.A.T.
According to USRSA they calculate the Power Index with the following formula:
Power index = (length index * stiffness index * headsize * swingweight index) / 1000
Beam thickness contributes to the stiffness of the frame. So the thinner frame (R1) must be built with stiffer material.
I agree. With manufactuerers' ability to manipulate the weight, density and stiffness of the material at will, it seems to me that the shape of the beam is largely, if not completely, irrelevant. It has more to do with marketing to a demographic than technological necessity. There, I said it!

The most glaring example I can think of is the (K) Factor (K)obra Tour. It's got the widest beam of any tweener racquet I've seen. Yet, Wilson calls it a "player frame." And, it plays more like a player frame than a tweener racquet because it's flex rating is 60, even though it has a wider beam than any tweener frame I've seen.

The reverse can be said for some flat beam racquest with a stiffness rating of 67 and higher, like the Wilson Pro Staff 88 or the Babolat Aero Storm Tour.
 
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