A golf club connecting apparatus for securely connecting a golf club shaft and a club head having a hosel portion is disclosed. The apparatus could be advantageously employed with various types of golf clubs. The apparatus comprises a hosel adapter, a shaft adapter, and at least one fastener, for example, a nut. The hosel adapter is configured to insert into the hosel portion such that the hosel adapter is positioned within the cylindrical sleeve of the hosel portion. The shaft adapter is securely affixed to the terminal end of the golf club shaft, wherein the shaft adapter is configured to insert into the hosel adapter via a longitudinal bore. The fastener is configured to threadably engage to the hosel adapter via the plurality of threads, thereby securing the club head and the golf club shaft together by inserting the shaft adapter into the hosel adapter.

A method of customizing a golf club, wherein the method includes generating operating data representative of a user operating a mechanical device. The operating data is generated by a first sensor sized and configured to be removably positioned in a mounting port formed on the mechanical device during operation of the mechanical device. The sensor is interchangeably positionable in the mounting port with at least one mass insert, the at least one mass insert being adapted to be interchangeably positioned in the mounting to provide at least two different mass configurations. The method further includes determining a recommended configuration of the at least one mass insert specific to the user based on the operating data generated by the sensor, and transmitting information representative of the recommended mass insert.

A method of customizing a golf club, wherein the method includes generating operating data representative of a user operating a mechanical device. The operating data is generated by a first sensor sized and configured to be removably positioned in a mounting port formed on the mechanical device during operation of the mechanical device. The sensor is interchangeably positionable in the mounting port with at least one mass insert, the at least one mass insert being adapted to be interchangeably positioned in the mounting to provide at least two different mass configurations. The method further includes determining a recommended configuration of the at least one mass insert specific to the user based on the operating data generated by the sensor, and transmitting information representative of the recommended mass insert.

A bat, which has a hollow barrel and an internal assembly configured to resist deformation of the hollow barrel, is disclosed. The internal assembly includes multiple rods disposed longitudinally within the hollow barrel. The internal assembly can include a deformable ring having a substantially circular outer wall having a diameter less than an inner diameter of the hollow barrel and multiple holes, with each hole configured to at least partially receive a rod of the multiple rods. The bat can have an end cap including end cap holes extending partially through the end cap, with each end cap hole configured to at least partially receive a rod.

Provided is a rigidity characteristics measuring device that measures the rigidity characteristics of a golf club head. A head fixing jig holds the golf club head with a face surface facing upward. A linear bushing causes an impact rod to drop vertically toward the golf club head. The impact rod is equipped with an acceleration sensor. A computer calculates the rigidity characteristics, e.g., a CT value, of the golf club head, based on a detected value of the acceleration sensor.

A golf club head includes a club body having a crown opposite a sole, a toe end opposite a heel end, a back end, and a hosel. A first magnet is coupled to the club body. A second magnet selectively engages the first magnet, such that in a first configuration the first and second magnets attract, and in a second configuration the first and second magnets do not attract, wherein the second magnet is configured to rotate relative to the first magnet between the first configuration and the second configuration.

A laser mandrel system that self-centers within a hosel bore of a golf club head to allow for precision adjustment of lie and loft is disclosed herein. The mandrel includes a one-piece housing with upper and lower portions, a laser centered within the upper portion of the housing, and a plurality of o-rings extending around an exterior or interior surface of a lower portion of the housing.

A laser mandrel system that self-centers within a hosel bore of a golf club head to allow for precision adjustment of lie and loft is disclosed herein. The mandrel includes a one-piece housing with upper and lower portions, a laser centered within the upper portion of the housing, and a plurality of o-rings extending around an exterior or interior surface of a lower portion of the housing.

Embodiments of putter-type golf club heads with adjustable loft and lie and methods of manufacturing of the same with adjustable loft and lie are generally described herein. These embodiments relate in particular to a putter-type club head with an adjustment portion that allows a user to change the loft and lie. The separate adjustment portions of the putter-type club head can couple the upper hosel to the body at a plurality of positions. An insert part of the adjustment portion has an upper section for receiving the upper hosel portion, a middle section, and a lower hosel portion. The sections of the adjustment portion can be coupled together by a fastener so that the sections are rotationally movable.

Embodiments of putter-type golf club heads with adjustable loft and lie and methods of manufacturing of the same with adjustable loft and lie are generally described herein. These embodiments relate in particular to a putter-type club head with an adjustment portion that allows a user to change the loft and lie. The separate adjustment portions of the putter-type club head can couple the upper hosel to the body at a plurality of positions. An insert part of the adjustment portion has an upper section for receiving the upper hosel portion, a middle section, and a lower hosel portion. The sections of the adjustment portion can be coupled together by a fastener so that the sections are rotationally movable.