A racket frame 2 includes a body 4 and a first vibration-damping portion 6 fixed to the body 4 . The body 4 includes a head 8 , a shaft 12 , a pair of throats 10 extending from the head 8 to the shaft 12 , and a grip 14 connected to the shaft 12 . The body 4 includes a second vibration-damping portion 18 , and the material of the second vibration-damping portion 18 is different from the material of the first vibration-damping portion 6 . The ratio (R 2 /R 4 ) of a side pressure rigidity R 2 to a throat rigidity R 4 is 0.26 or greater, a moment of inertia around an axis at a position of 10 cm from a grip end is less than 300 kg·cm 2 , and a vibration damping rate in an out-of-plane secondary mode is equal to or greater than 0.70 but equal to or less than 1.0.
1. A racket frame comprising a body and a first vibration-damping portion fixed to the body, wherein
the body includes a head, a shaft, a pair of throats extending from the head to the shaft, and a grip connected to the shaft,
the body includes a second vibration-damping portion,
a material of the second vibration-damping portion is different from a material of the first vibration-damping portion,
a ratio (R 2 /R 4 ) of a side pressure rigidity R 2 to a throat rigidity R 4 is equal to or greater than 0.26,
a moment of inertia around an axis at a position of 10 cm from a grip end is less than 300 kg·cm 2 , and
a vibration damping rate in an out-of-plane secondary mode is equal to or greater than 0.70 but equal to or less than 1.0.
2. The racket frame according to claim 1 , wherein the first vibration-damping portion is formed from a fiber reinforced nylon.
3. The racket frame according to claim 1 , wherein the second vibration-damping portion is formed from an epoxy resin.
4. The racket frame according to claim 1 , wherein
the first vibration-damping portion is fixed to each throat, the shaft, or the grip, and
the second vibration-damping portion is included in the head or each throat.
5. The racket frame according to claim 4 , wherein the first vibration-damping portion extends from each throat to the grip.
6. The racket frame according to claim 4 , wherein
the head includes a pair of second vibration-damping portions, and
these second vibration-damping portions are located so as to be symmetrical about the axis of the racket frame.
7. The racket frame according to claim 4 , wherein
each throat includes the second vibration-damping portion, and
these second vibration-damping portions are located so as to be symmetrical about the axis of the racket frame.
8. The racket frame according to claim 1 , wherein
the side pressure rigidity R 2 is equal to or greater than 95 kgf/cm, and
the throat rigidity R 4 is equal to or less than 350 kgf/cm.
9. The racket frame according to claim 1 , wherein the ratio (R 2 /R 4 ) is equal to or greater than 0.28.
10. The racket frame according to claim 1 , wherein the moment of inertia is less than 295 kg·cm 2 .