Golf club head

A golf club head comprising:

• a club head body having a leading edge, a trailing edge, an upper portion, a lower portion, a heel portion, a toe portion, a striking face, a rear portion opposite the striking face, a forward portion, a center of gravity (CG), and a golf club shaft receiving portion positioned in the heel portion and configured to receive a golf club shaft, the golf club shaft receiving portion comprising an upper shaft opening in the upper portion of the golf club head and a lower shaft opening in the lower portion of the golf club head, with the club head body defining an interior cavity, wherein:
• the upper portion is defined as a portion of the golf club head located above a peripheral outline of the golf club head as viewed from a top-down direction;
• the lower portion is defined as a portion of the golf club head extending upwards from a lowest point of the golf club head when in a normal address position, to the peripheral outline of the golf club head;
• the forward portion of the golf club head extends towards the striking face from the CG of the golf club head, and the rear portion of the golf club head extends towards the trailing edge from the CG of the golf club head;
• the striking face including a geometric center defining an origin of a coordinate system when the golf club head is at the normal address position, the coordinate system including:
• an x-axis being tangent to the striking face at the origin and parallel to a ground plane, wherein the x-axis extends in a positive direction from the origin to the heel portion of the club head body,
• a y-axis intersecting the origin being parallel to the ground plane and orthogonal to the x-axis, wherein the y-axis extends in a positive direction from the origin to the rear portion of the club head body, and
• a z-axis intersecting the origin being orthogonal to both the x-axis and the y-axis, wherein the z-axis extends in a positive direction from the origin to the upper portion of the club head body, wherein:
• the heel portion extends towards, and includes, the golf club shaft receiving portion from a y-z plane passing through the origin, and
• the toe portion is defined as a portion of the golf club head extending from the y-z plane in a direction opposite the heel portion;
• an adjustable head-shaft connection assembly that is operable to adjust at least one of a loft angle or lie angle of a golf club formed when the golf club head is attached to a golf club shaft via the head-shaft connection assembly;
• a first weight configured to engage the lower portion at a first position and a second weight configured to engage the lower portion at a second position, wherein the first position is in the forward portion of the golf club head and a central axis of the first weight extends through the upper portion;
• and
• a lower recessed portion in the lower portion of the golf club head positioned proximate to the lower shaft opening and at least partially surrounding the lower shaft opening,
• wherein:
• the lower shaft opening is in communication with the upper shaft opening and
• the lower recessed portion having one or more walls extending into the interior cavity of the club head body;
• wherein there is a face-to-upper portion transition where the face connects to the upper portion near a front end of the club head body;
• wherein in the y-z plane passing through the origin, a crown height continuously increases starting from the face-to-upper portion transition up to a local maximum;
• wherein a coefficient of restitution of the golf club head measured at the geometric center of the face is 0.80 or greater;
• wherein a mass of the golf club head is between about 185 grams and about 245 grams;
• wherein a maximum dimension from a forward portion to a rearward portion of the golf club head is greater than about 75 mm, wherein the forward portion extends towards the striking face from the CG of the golf club head, and wherein the rearward portion extends towards the trailing edge from the CG of the golf club head;
• and
• wherein:
• the golf club head has an above ground center-of-gravity location Zup measured in mm;
• the golf club head has a moment of inertia about a center-of-gravity z-axis Izz measured in kg-mm2 greater than 360 kg-mm2;
• the golf club head has a moment of inertia about a center-of-gravity x-axis Ixx measured in kg-mm2;
• and
• Izz and Ixx are related to the above ground center-of-gravity location Zup by an equation Ixx+Izz≥20·Zup+165;
• Izz is related to the above ground center-of-gravity location Zup by an equation Izz≥13·Zup+105;
• Ixx is related to the above ground center-of-gravity location Zup by an equation Ixx≥7·Zup+60;
• and
• a center of gravity of the first weight is located within about 30 mm of a nearest portion of a forward edge of a sole of the golf club head.