Abstract: The present invention provides a shaft for a golf club which is constructed such that overlapped joints are formed therein, thus providing effects of increasing the distance that a golf ball is driven, and of preventing the shaft of the golf club from momentarily twisting. To achieve the above-mentioned purpose, the shaft of the present invention includes an inner layer (110), which is provided at an innermost position, a middle layer (120), which is laminated around the circumferential outer surface of the inner layer, and an outer layer (130), which is laminated around the circumferential outer surface of the middle layer. The middle layer comprises a plurality of middle layer sheets, which are arranged in a longitudinal direction of the golf shaft such that the middle layer sheets partially overlap each other to form overlapped joints.

Abstract: A golf club shaft that has a flexural rigidity distribution allows a user to easily adjust swing timing even when a golf club using the golf club shaft is long. The golf club shaft comprises a section between a point 500 mm and a point 800 mm from a tip end of the shaft, wherein the flexural rigidity El of the shaft monotonically increases in the section from the point 500 mm to the point 800 mm, wherein ?1/?2 is at least about 1.5 provided that the rate of change of the flexural rigidity EI of the shaft in a first subsection between a point 500 mm and a point 600 mm from the tip end is denoted by ?1, and the rate of change of the flexural rigidity EI of the shaft in a second subsection between a point 700 mm and a point 800 mm from the tip end is denoted by ?2, and wherein the flexural rigidity EI of the shaft at a point 750 mm from the tip end is at least about 4.1×106 kgf*mm2.

Abstract: It is object of the present invention to provide a golf club shaft superior in accuracy, minimizing a displacement between thermosetting resin layers, capable of obtaining a feeling close to the feeling of a steel shaft, and superior in stability.

Abstract: A golf club shaft composed of a laminate of prepregs. A part of the laminate is formed as a fullerene-containing bias layer BF composed of prepregs containing a matrix resin and fullerene and/or a fullerene compound contained in the matrix resin. Reinforcing fibers of the prepregs form an angle of not less than ±10° nor more than ±80° to the axis of the shaft.

Abstract: A shaft according to the present invention is obtained by winding and curing a prepreg sheet having a matrix resin and a fiber. The prepreg sheet includes a full-length sheet and a partial sheet. At least a part of the partial sheet forms a tip bias layer disposed in a tip portion of the shaft. A fiber of the first tip bias layer is oriented at an angle which is equal to or greater than 25 degrees and is equal to or smaller than 65 degrees with respect to an axis of the shaft. A fiber of the second tip bias layer is oriented at an angle which is equal to or greater than ?65 degrees and is equal to or smaller than ?25 degrees with respect to the axis of the shaft. The shaft is obtained by winding a tip bias stuck body (V1) fabricated by sticking a first tip bias sheet (a8) and a second tip bias sheet (a9) together.

Abstract: It is object of the present invention to provide a golf club shaft superior in accuracy, minimizing a displacement between thermosetting resin layers, capable of obtaining a feeling close to the feeling of a steel shaft, and superior in stability.

Abstract: A golf club shaft is provided that has a grip end opposite a head end and defining a length of the shaft extending between those two ends. The shaft has a tubular cross-section over at least one portion of the shaft length which cross-section has a substantially circular outer periphery and a polygon inner periphery formed of a plurality of between 4 and 24 flats, and preferably formed of 8-16 flats. A mandrel having the shape of the inner periphery of the shaft is also provided, as is a method of forming the shaft that uses the mandrel and composite matrix materials.

Abstract: A graphite golf club which is formed by a mandrel is provided.

Abstract: A method of applying a cover to a shaft of a golf club includes fitting the cover onto the golf club such that a shaft of the club passes through a sleeve of heat-shrinkable material adapted to fit around an exposed portion of the shaft, positioning the cover such that the sleeve is substantially in register with the exposed portion of the shaft, and applying heat to the sleeve to cause the sleeve to shrink onto the exposed portion of the shaft.

Abstract: Points obtained by plotting flexural rigidity EI measured at ten sites on a shaft are defined as from T (1) to T (10) in this order from the head side, and the formula representing a line K that passes the T (1) and the T (10) is defined as [Y=aX+b1]. The values at the Y-intercepts on the lines that are parallel to the line K and that pass the points of from T (2) to T (9), respectively, are defined as from b2 to b9, respectively, and the minimum value among the values at the Y-intercepts b2 to b9 is defined as bmin. Slope “a” of the line K is 0.04 or greater and 0.06 or less; every one of the b3, b4, b5, b6, b7 and b8 is smaller than b1; and the bmin is any one of b4 to b7. The value (b1?bmin) is 30 (N·m2) or greater and 40 (N·m2) or less, and the value (b9?b1) is 4 (N·m2) or greater and 15 (N·m2) or less. This shaft either has a high-strength straight layer and a hoop layer, or has a textile layer.

Abstract: A golf club shaft composed of a laminate of prepregs each containing a matrix resin and reinforcing fibers impregnated with the matrix resin. The matrix resin of at least one of the prepregs contains a fullerene or/and a fullerene compound. The content of the fullerene or/and the fullerene compound contained in the prepreg is set to not less than 0.002 wt % nor more than 1 wt % of an entire weight of the prepreg. The length of the prepreg containing the fullerene or/and the fullerene compound is set to not less than 2% nor more than 90% of the full length of the golf club shaft.

Abstract: A shaft 6 is formed by a prepreg sheet. The sheet of the shaft 6 includes full length sheets (a2), (a3), (a8) and (a11) provided wholly in a longitudinal direction of the shaft, and partial sheets (a1), (a4), (a5), (a6), (a7), (a9), (a10) and (a12) provided partially in the longitudinal direction of the shaft. The number of the full length sheets is equal to or greater than two. The number of the partial sheets is equal to or greater than four. Each of the partial sheets has an end.

Abstract: A golf club shaft (10), tubular and having a hollow portion, which includes a laminate of fiber reinforced prepregs (21 through 23, 24A, 25 through 29). The laminate has a first part (I) composed of a plurality of first prepregs (P1) and a second part (P2). A loss factor (tan ?) of the first part (I) is set to not less than 0.005 nor more than 0.02, when the loss factor is measured at a frequency of 10 Hz under a condition of 10° C. A loss factor (tan ?) of the second part (P2) is set to not less than 0.10 nor more than 0.50, when the loss factor is measured at a frequency of 10 Hz under the condition of 10° C.

Abstract: A golf club shaft (10) having a weight not less than 30 g nor more than 60 g. The golf club shaft (10) includes a bias layer (B1) composed of a prepreg whose reinforcing fibers have an orientation angle of not less than ±10° nor more than 80° to an axis of the golf club shaft (10) and a straight layers (A1 through A6) each composed of a prepreg whose reinforcing fibers have an orientation angle within 0°±10° to the axis of the golf club shaft (10). At least one partial reinforcing hoop layer whose reinforcing fibers have an orientation angle of within 90°±10° to the axis of the golf club shaft (10) is disposed in only an important reinforcing region in a range from a point (P) spaced at 15% of a full length (L) of the golf club shaft (10) from a grip-side butt (12) thereof to a point (Q) spaced at 45% of the full length (L) of the golf club shaft (10) from the grip-side butt (12) thereof.

Abstract: It is a sport equipment 2 using a partially hardened sheet form prepreg 10 formed by impregnating a reinforced fiber material 6 disposed substantially parallel with a thermal hardening resin material 7 to bind the reinforced fiber material, where the prepreg is layered so as to form a tube rod in a tapered shape having a diameter increasing from one end to the other, and the tube rod is provided with a strengthening means on a radially entire circumference to the axis direction. Herewith it is especially used for a golf club shaft, while maintaining a characteristic of light weight, securing strength equal to or greater than a steel-made golf shaft, and suppressing unnecessary deflection and vibration, so as to provide a sports equipment made of a reinforced fiber combined material such as a gold club shaft having high strength such as bending and twisting rigidity.

Abstract: A precise impact and increased ball drive distance may be achieved due to an increase of elastic force and restoring force of a golf club shaft, when the golf club shaft includes: a first shell portion interiorly disposed in the golf club shaft; at least one elastic member disposed in a length direction on an exterior circumference of the first shell portion; and a second shell portion including carbon and enclosing the first shell portion and the at least one member.

Abstract: Each point obtained by plotting flexural rigidity EI measured at ten sites on a shaft is defined as from T(1) to T(10) in this order from the head side, and the formula representing a line K that passes the T(1) and the T(10) is [Y=aX+b1]. The values at the Y-intercepts on the lines that are parallel to the line K and that pass the points of from T(2) to T(9), respectively, are defined as from b2 to b9, respectively, and the minimum value among the values at the Y-intercept b2 to b9 is defined as bmin. In this shaft, slope “a” of the line K is 0.04 or greater and 0.06 or less; any one of the b3, b4, b5, b6, b7 and b8 is smaller than b1; and the bmin is any one of b4 to b7. The value (b1?bmin) is 24 (N·m2) or greater and 35 (N·m2) or less, and the value (b9?b1) is 0 or greater and 10 (N·m2) or less. This shaft achieves excellent flight distance performance and directionality of the hit ball.

Abstract: A club shaft for an iron-type golf club is made of a fiber reinforced resin. The weight W of the club shaft per 39 inches is not less than 55 grams and not more than 95 grams. The average bending rigidity EIa of the club shaft is not more than 1.5 kgf sq.m. An expression (1) EIa=<0.05W?1.25 is satisfied. Preferably, an expression (2) EIa=<0.05W?1.75 is satisfied. More preferably, an expression (3) EIa>=0.1W?6.5 is satisfied. Even if golfers are weak in flexing the club shafts though the golf swings are powerful, the carry distance can be increased.

Abstract: A club shaft for an iron-type golf club is made of a fiber reinforced resin. The weight W of the club shaft per 39 inches is not less than 30 grams and not more than 60 grams. The average bending rigidity EIa of the club shaft is not more than 5.0 kgf sq.m. An expression (1) EIa>=0.05 W+2.0 is satisfied. Preferably, an expression (2) EIa>=0.05 W+2.5 is satisfied. More preferably, an expression (3) EIa>=(1/15)W+2.0 is satisfied. Even if golfers can not make powerful swings through the swing speed is high, the carry distance and the directionality of the hit ball can be improved.

Abstract: A golf club shaft composed of a laminate of a plurality of carbon fiber reinforced prepreg sheets having a length equal to the full length of the golf club shaft and are sequentially wound round a mandrel. Per-area weights of the carbon fibers of the carbon fiber prepreg sheets having the length equal to the full length of the golf club shaft are gradually increased from an innermost-layer CF prepreg sheet to an outermost-layer carbon fiber prepreg sheet in such a way that the per-area weight of the outermost-layer carbon fiber prepreg sheet is set larger than that of the innermost-layer CF prepreg sheet.

Abstract: A composite golf club shaft having a reinforcing ribbon of composite material spiraling along an intermediate portion of the shaft and bonded thereto to reinforce the hoop strength of the shaft. The ribbon is shaped into a rib of different cross-sectional shapes, the preferred embodiment being a thin rectangular shape approximately 0.125 wide of an inch and spiraling at a rate of four turns per inch, producing a groove of equal width. The methods of the invention produces the shaft by providing a mandrel having the outside shape desired for the shaft's inside surface; wrapping a ribbon of reinforcing material around the shaft in a spiral groove therein; forming the shaft body around the mandrel; and separating the mandrel from the shaft after curing, by unscrewing the mandrel.

Abstract: A wood golf club (10) which is not less than 44 inches in a length thereof and whose head (14) is not less than 190 g in a weight thereof. The value of a ratio of a rigidity value EIt at a position spaced at an interval of 130 mm from a head-side front end of a shaft (11) of the golf club (10) to a rigidity value EIb at a position spaced at an interval of 250 mm from a grip-side rear end of the shaft (11) is set to not less than 0.50.

Abstract: Points obtained by plotting flexural rigidity EI measured at ten sites on a shaft are defined as from T (1) to T (10) in this order from the head side, and the formula representing a line K that passes the T (1) and the T (10) is defined as [Y=aX+b1]. The values at the Y-intercepts on the lines that are parallel to the line K and that pass the points of from T (2) to T (9), respectively, are defined as from b2 to b9, respectively, and the minimum value among the values at the Y-intercepts b2 to b9 is defined as bmin. Slope “a” of the line K is 0.04 or greater and 0.06 or less; every one of the b3, b4, b5, b6, b7 and b8 is smaller than b1; and the bmin is any one of b4 to b7. The value (b1?bmin) is 30 (N·m2) or greater and 40 (N·m2) or less, and the value (b9?b1) is 4 (N·m2) or greater and 15 (N·m2) or less. This shaft either has a high-strength straight layer and a hoop layer, or has a textile layer.

Abstract: A light-weighted golf club shaft, which can stabilize the swing orbit of a club head during a swing and can allow a player to swing a golf club easily and to have a consistent shot pattern, is provided. The golf club shaft has a length of 42 to 48 inches and a weight of 35 to 50 grams. A center of gravity of the shaft is located within 46.0 to 49.0% of its entire length from its tip end and a torque to the tip-end of the shaft ranges between 3.0 and 4.5 degrees. The shaft may comprise a longitudinal layer and a biased layer. The biased layer may comprise carbon fibers having a modulus of elasticity of not less than 40 t/mm2. The ratio of the number of turns of prepreg sheets for the biased layer in the tip-end portion to that in the butt-end portion of the shaft may range between 3:1 and 3:2.

Abstract: A golf club shaft (10), tubular and having a hollow portion, which includes a laminate of fiber reinforced prepregs (21 through 23, 24A, 25 through 29). The laminate has a first part (I) composed of a plurality of first prepregs (P1) and a second part (P2). A loss factor (tan ?) of the first part (I) is set to not less than 0.005 nor more than 0.02, when the loss factor is measured at a frequency of 10 Hz under a condition of 10° C. A loss factor (tan ?) of the second part (P2) is set to not less than 0.10 nor more than 0.50, when the loss factor is measured at a frequency of 10 Hz under the condition of 10° C.

Abstract: A golf club comprises a club shaft having a tip end and a butt end, a club head being attached to the tip end of the club shaft, and a golf grip being attached to a region of the club shaft extending from the butt end toward the tip end of the club shaft, the grip having an end by the side of the butt end of the club shaft, wherein the club head has an moment (M) of inertia around a center line of the club shaft of not less than 6500 g·cm2, and the club shaft has a bending stiffness (E) of not less than 5.0×106 kgf·mm2 at the position which separates 200 mm from the end of the grip toward the club head.

Abstract: A golf club shaft 2 made of a fiber-reinforced resin having a weight W of 30 to 55 g calculated as a shaft having a length of 46 inches and an average flexural rigidity EIa of 1.5 to 4.0 kgf·m2 and satisfying the equation: EIa?0.1W?1.5. Since it is light weight but has a relatively high flexural rigidity, a golf club can be swung at high speed without deteriorating the flight direction performance.

Abstract: A golf club shaft having at least six full-length layers composed of prepregs. The full-length layers are divided into an inner-layer part including a half of the full-length layers and an outer-layer part including a remaining half of the full-length layers. At least one pair of the full-length layers is formed as a bias set layer in each of the inner-layer part and the outer-layer part by layering two bias layers with each other, with reinforcing fibers of the bias layers intersecting with each other at an orientation angle of ±?° which fall in a range from ±25° to ±65° with respect to an axis of the golf club shaft. A straight layer is formed as an outermost full-length layer of the outer-layer part with reinforcing fiber thereof orienting at the range from 0° to ±10° with respect to the axis of the shaft.

Abstract: A composite golf club shaft having a reinforcing ribbon of composite material spiraling along an intermediate portion of the shaft and bonded thereto to reinforce the hoop strength of the shaft. The ribbon is shaped into a rib of different cross-sectional shapes, the preferred embodiment being a thin rectangular shape approximately 0.125 wide of an inch and spiraling at a rate of four turns per inch, producing a groove of equal width. The methods of the invention produces the shaft by providing a mandrel having the outside shape desired for the shaft's inside surface; wrapping a ribbon of reinforcing material around the shaft in a spiral groove therein; forming the shaft body around the mandrel; and separating the mandrel from the shaft after curing, by unscrewing the mandrel.

Abstract: It is object of the present invention to provide a golf club shaft superior in accuracy, minimizing a displacement between thermosetting resin layers, capable of obtaining a feeling close to the feeling of a steel shaft, and superior in stability.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: A wood-type golf club including a club shaft and a club head, wherein the club length is in a range of from 43 to 48 inches, the volume of the club head is in a range of not less than 250 cc, and the torque T in degree of the club shaft and the gravity point distance L in mm between the gravity point of the club head and the center line of the club shaft satisfy conditions (1) T?0.143L?2.79 and (2) T?0.286L?7.14.

Abstract: A golf club comprises a club shaft and a hollow club head, wherein the club head has a loft angle of from 14 to 18 degrees, a head volume of not less than 250 cc, and a sweet spot at a vertical distance of from 1 to 5 mm downwards of a face center, and the club shaft has a variable flexural rigidity whose minimum is in a range of from 5 to 10 N·m2, and the minimum flexural rigidity occurs in a range between 0% and 40% of the length of the club shaft from the end of the club shaft.

Abstract: A golf club shaft whose outer diameter is set to 9.5 to 12 mm in at least one portion of a range from a tip thereof to a position located at 25% of the distance from the tip to its butt. The minimum value of a flexural rigidity (EI) is set to 1.00 to 2.50 kg·m2. A reinforcing layer is formed in the region disposed from the tip to the position located at about 25% of the distance from the tip to the butt. The layer includes at least one straight layer whose reinforcing fiber has a tensile modulus of elasticity of 5 to 15 ton/mm2 and is parallel with an axis of the shaft and one angular layer whose reinforcing fiber has a tensile modulus of elasticity of 24 to 40 ton/mm2 and an orientation angle of ±20 to 65°.

Abstract: A golf shaft made of fiber reinforced plastic and including a tip portion attached to a head, a butt portion attached to a grip, and a middle portion located between the tip portion and the butt portion. The golf shaft has a generally tapered shape in which the outer diameter generally increases gradually from the tip portion to the butt portion. The golf shaft includes a first portion in which linear density is generally uniform. A second portion is defined by the part of the shaft excluding the first portion. The first portion occupies 30% or more of the entire shaft length, and the linear density of the first portion is greater than that of the linear density.

Abstract: In a putter shaft having a tip end and a butt end, a curvature of the putter shaft is represented by a curvature curve of the putter shaft which increases monotonously from the tip end to the butt end. The curvature curve is defined as a curve showing variation of the curvature in a longitudinal axis direction of the putter shaft in a state where a load acts on the tip end to deform the putter shaft with the putter shaft being fixed at the butt end.

Abstract: A golf club shaft having a structure of a plurality of fiber reinforced prepregs layered one upon another. A grip-side reinforcing layer 6 (6A, 6B) and a head-side reinforcing layer 5 (5A, 5B, and 5C) are provided. In each of the grip-side reinforcing layer and the head-side reinforcing layer, a length of at least one of the prepregs is different from that of the other prepregs in an axial direction thereof, and the number of layers of the prepregs disposed at both ends of the golf club shaft is set larger than that of layers thereof disposed at a middle part of the golf club shaft.

Abstract: A golf club shaft having a fiber reinforced thermosetting resinous material (10) and a fiber reinforced thermoplastic resinous material (20), wherein the fiber reinforced thermoplastic resinous material (20) having a vibration-damping factor not less than 1.0 has a weight not less than 10% nor more than 60% of a weight of the golf club shaft. The fiber reinforced thermoplastic resinous material (20) is disposed on a part of a peripheral surface of the golf club shaft, on an inner peripheral surface thereof or between layers of the fiber reinforced thermosetting resinous material (10).

Abstract: A golf club shaft (1) in which a difference between a maximum EI value and a maximum EI value in the range from a tip (1a) to a position spaced therefrom at a distance corresponding to not less than 40% nor more than 60% of the whole length of the shaft (1) is set to less than 10% of the average of the maximum EI value and the minimum EI value in the range. The diameter of the tip (1a) of the shaft (1) is set to not less than 9.0 mm nor more than 12.0 mm. The shaft (1) is applied to an iron club set consisting of a plurality of iron golf clubs having different numbers.

Abstract: A golf club shaft has an angular layer composed of prepregs in which a reinforcing fiber inclines to the axis of the golf club shaft; a plurality of straight layers composed of prepregs in which the reinforcing fiber is disposed substantially parallel with the axis of the golf club shaft. The reinforcing fiber of the prepreg at an inner side of the straight layer has an intermediate elasticity and a high strength. The tensile break strain of the prepreg at an outer side of the straight-layer is set higher than that of the prepreg at the inner side of the straight layer.

Abstract: A golf club shaft is 35-50 percent lighter than a conventional shaft while maintaining the outer diameter and structural characteristics of conventional shafts. The shaft has at least four layers of fiber reinforced material. The fiber reinforced layers are from innermost to outermost: a first angled layer; a first straight layer; a second angled layer; and a second straight layer. The angled layers are formed by bonding together two materials, each with fibers aligned in different directions. The second angled layer maintains the proper strength and rigidity of the shaft while keeping the shaft as light weight as possible. Aligning the second layer's fibers at an angle of 35-75 degrees with respect to the longitudinal direction of the shaft ensures proper weight and strength characteristics of the shaft. The resulting shaft is light-weight and exhibits the flexural rigidity, flexural strength, torsional rigidity, torsional strength, and crushing strength of conventional shafts.

Abstract: In a golf club shaft, composed of a laminate of prepregs made of a fiber reinforced resin, the weight of a unit length of the golf club shaft in the axial direction thereof is set to not less than 0.25 g/cm nor more than 0.60 g/cm. Supposing that reinforcing fibers of the prepregs of a straight layer are parallel with the axial direction of the golf club shaft and that tensile moduli of elasticity of the reinforcing fibers are sequentially denoted by N1, N2, . . . Nn in the order from an innermost layer of the laminate to an outermost layer thereof, N1?N2? . . . Nn and N1>Nn (n is an integer not less than 2) is established in a range at least 10% of the whole length of the golf club shaft.

Abstract: A golf club shaft composed of a laminate of prepregs obtained by impregnating reinforcing fibers with a resin, the weight (g) of the golf club shaft per unit length (mm) is less than 0.0385 g/mm. Prepregs, each including a reinforcing fiber having a high tensile modulus of elasticity not less than 300 GPa and a high tensile strength not less than 5000 MPa are disposed as a part of a straight layer in which the reinforcing fibers are parallel with the axial direction of the golf club shaft.

Abstract: A golf club shaft formed by winding prepregs of an angular layer and those of a straight layer around a mandrel (10) having a steeply tapered part (10B) formed at a tip side thereof and a gently tapered part (10C) formed, at a butt side thereof, continuously with the steeply tapered part (10B). Prepregs (17, 18) of the angular layer are disposed at the tip side of the mandrel (10). Butt-side ends (17a, 18a) of the prepregs (17, 18) of the angular reinforcing layer at the tip side of the mandrel (10) are disposed at the butt side of the mandrel (10) with respect to a boundary position (P2) disposed at a boundary between the steeply tapered part (10B) and the gently tapered part (10C). A distance from the butt-side ends (17a, 18a) of the prepregs (17, 18) of the angular reinforcing layer at the tip side of the mandrel (10) to the boundary position (P2) is not less than 5% nor more than 30% of a whole length of the shaft.

Abstract: A golf club shaft 1 has a prepreg (15) consisting of an intermediate-elasticity and high-strength carbon fiber reinforced resinous sheet having a tensile modulus of elasticity of 30 ton/mm2 to 33 ton/mm2 and a tensile strength of not less than 5000 MPa and a prepreg (16) consisting of a low-elasticity carbon fiber reinforced resinous sheet having a tensile modulus of elasticity of 5 ton/mm2 to 10 ton/mm2 and compressive breaking strain of not less than 2.0%. The prepregs (15) and the prepregs (16) are used to reinforce a tip side of the golf club shaft.

Abstract: A composite golf club shaft is constructed having a reduced butt diameter of 0.400 to 0.560 inches in diameter. The shaft tapers without intentional discontinuities from the reduced-diameter butt section to a cylindrical tip portion having a standard tip diameter adapted to be attached to the hosel of a club head. By reducing the diameter of the butt portion of the shaft while maintaining the shaft free of substantial discontinuities, lead-lag flexure is increased uniformly, thereby improving the controllability of the shaft, and without inducing the artificial bending modes found in bubble shafts and other shaft configurations having intentional discontinuities.

Abstract: A golf shaft made of fiber reinforced plastic and including a tip portion attached to a head, a butt portion attached to a grip, and a middle portion located between the tip portion and the butt portion. The golf shaft has a generally tapered shape in which the outer diameter generally increases gradually from the tip portion to the butt portion. The golf shaft includes a first portion in which linear density is generally uniform. A second portion is defined by the part of the shaft excluding the first portion. The first portion occupies 30% or more of the entire shaft length, and the linear density of the first portion is greater than that of the linear density.

Abstract: At least one layer of inclined prepregs having reinforcing fiber oriented an angles not 0° and 90° with respect to the axis of a golf club shaft is wound by unintegral turns more than zero at at least one part of the golf club shaft in an axial direction thereof. A part of the prepreg(s) corresponding to partial turns obtained by subtracting integral turns form the unintegral turns forms an anisotropic region. In this manner, it is possible to obtain an anisotropic shaft in which the angle of the reinforce fiber is partly different from that of other parts in the circumferential direction of the shaft and further, at at east one part in the thickness direction thereof.

Abstract: A golf club shaft is 35-50 percent lighter than a conventional shaft while maintaining the outer diameter and structural characteristics of conventional shafts. The shaft has at least four layers of fiber reinforced material. The fiber reinforced layers are from innermost to outermost: a first angled layer; a first straight layer; a second angled layer; and a second straight layer. The angled layers are formed by bonding together two materials, each with fibers aligned in different directions. The second angled layer maintains the proper strength and rigidity of the shaft while keeping the shaft as light weight as possible. Aligning the second layer's fibers at an angle of 35-75 degrees with respect to the longitudinal direction of the shaft ensures proper weight and strength characteristics of the shaft. The resulting shaft is light-weight and exhibits the flexural rigidity, flexural strength, torsional rigidity, torsional strength, and crushing strength of conventional shafts.