# Weighting = swing weight?

Discussion in 'Racquets' started by jackson vile, Mar 29, 2006.

1. ### jackson vileLegend

Joined:
Apr 19, 2005
Messages:
9,809
I am wondering what amount of grams put at the tip of the racket will result in how many points in swing weight?

2. ### loubapacheProfessional

Joined:
Oct 31, 2004
Messages:
856
Location:
USA
If it is a 27" racquet, every gram of mass at the 12 o'clock position will increase the swing weight by approximately 3.4 kgcm^2.

27" = 68.58 cm but the swing weight is about 10 cm from the end of the handle so from the tip the distance is 58.58 cm. Each gram is 0.001 kg so the contribution is

(0.001 kg)(58.58 cm)^2 = 3.4 kg cm^2.

^2 means square.

3. ### rich sHall of Fame

Joined:
Feb 18, 2004
Messages:
2,528
Location:
ATL
swingweight isn't measured in points, it is measured in kg-cm^2 and 1 gram of lead on a 27 in racquet at the 12 o'clock position would equate to ~3.4 kg-cm^2 of additional inertia.

on a 27 1/4" frame 1 g @12 o/c = ~3.5 kg-cm^2
and
on a 27 1/2" frame 1 g @12 o/c = ~3.6 kg-cm^2

4. ### jackson vileLegend

Joined:
Apr 19, 2005
Messages:
9,809
Sorry that is just what I called it, I thought it was in grams but you say that it is measured in kg?

I am a bit confused by the equation (0.001 kg)(58.58 cm)^2 = 3.4 kg cm^2.

How does this reperesent say a SW of 330? What is the SW that is described at TW measured as?

5. ### loubapacheProfessional

Joined:
Oct 31, 2004
Messages:
856
Location:
USA
Swing weight is measured in kg cm^2. If a racquet has a swing weight of 330, then it is 330 kg cm^2. So on that racquet, if you stick 1 gram of lead tape at the 12 o'clock position, its swing weight will be 330 + 3.4 = 333.

6. ### jackson vileLegend

Joined:
Apr 19, 2005
Messages:
9,809

Really!? That is all 1 gram adds? I thought it would be more.

Thank you for clearing that up for me, I didn't payattention as it just made no sense as I thought adding any weight to the tip no matter how minor would make a big differnce?

7. ### loubapacheProfessional

Joined:
Oct 31, 2004
Messages:
856
Location:
USA
Actually, 1 gram of mass for 3.4 kg cm^2 of swing weight is a lot.

Let's say that 330 swing weight racquet has a mass of 330 grams. On average, each gram is only contributing to 1 kg cm^2 of swing weight (because not all mass is at the 12 o'clock).

Now this added 1 gram generated 3.4 kg cm^2. That is quite large, compared to the rest of the racquet mass.

Joined:
Feb 18, 2004
Messages:
2,528
Location:
ATL

well stated!

9. ### byealmeensSemi-Pro

Joined:
Mar 23, 2005
Messages:
488
I second that - very well-sated! I would add that very rarely does anyone add just one gram of weight. You often hear players talk about adding 5 grams or so at the tip. Many don't realize they are increasing SW by 17 kg cm2. That is quite a bit.

10. ### loubapacheProfessional

Joined:
Oct 31, 2004
Messages:
856
Location:
USA
Thanks, Rich and byealmeens.

Yes, many times people do it in 3 grams increments. That is 6 inches of 1/2" lead tape and increases the SW by about 10 kg cm^2.