Every Term That Appears on Your Card
Fitting vocabulary is not complicated, it is just unfamiliar. This page defines each specification we write down, in the order it gets decided during a session.
Grip Specifications
These get set first, because everything downstream depends on them.
Core size
The internal diameter of the grip, matched to the butt diameter of the shaft. Common cores are 0.580 and 0.600 inches. A 0.600 core on a 0.580 butt sits loose and finishes thinner than intended, which is a surprisingly common cause of a grip feeling "small" no matter what size is printed on it.
Build-up
Layers of double-sided tape wrapped under the grip to increase finished diameter. Each full wrap adds roughly one sixty-fourth of an inch. Build-up is how we hit a diameter that no off-the-shelf size offers, and it can be applied unevenly — more under the lead hand than the trail hand — where a player's hands differ.
Taper reduction
Grips are conical: wider at the butt, narrower at the lower hand. Reducing that taper by building up the lower portion gives the trail hand more to hold, which usually calms down a grip pressure spike at the top of the backswing. Popular with players who fight an early release.
Compound and construction
Rubber, corded, hybrid and polyurethane wrap behave differently in humidity. In a Florida summer, a soft rubber compound that feels beautiful in the shop can go slick in the hand by the fourth hole. Cord content buys grip at the cost of comfort, and hybrids split the difference across the two hands.
Grip cross-section
Round, ribbed, or a defined flat front, mostly relevant on putters. A squarer cross-section gives the hands a reference edge, which tends to tighten start line. A round section leaves the hands free to find their own position, which some players prefer and others quietly fight all the way through the stroke.
Shaft Specifications
Decided after the grip build is set, so the numbers reflect how you actually hold the club.
Raw weight
The mass of the shaft in grams before trimming. It is the single largest lever on how a club feels, more so than flex. Iron shafts commonly run from about 95g to 130g in steel and 55g to 95g in graphite; wood shafts from roughly 40g to 80g.
Flex and frequency
Flex letters — L, A, R, S, X — are marketing categories, not measurements. Two shafts both stamped S can differ by more than a full flex once measured. Frequency, expressed in cycles per minute on a deflection machine, is the actual number, and it is what we record.
Bend profile
Where along the shaft the bending happens under load. Described loosely as low, mid or high launch, though the useful version is the stiffness distribution across butt, middle and tip sections. Two shafts with identical frequency and different profiles will produce noticeably different flight.
Torque
Resistance to twisting around the shaft's own axis, in degrees. Lower resists more. It is not a scoreboard: a smooth-tempo player often prefers more torque for feel, while an aggressive transition usually wants less. Torque values are also not comparable across manufacturers, since measurement methods differ.
Tip and butt trimming
How much material is removed from each end before assembly. Tip trimming stiffens the tip section and lowers launch; butt trimming shortens the club and stiffens it overall. Every shaft model has a manufacturer trimming chart, and ignoring it is one of the most common errors in amateur reshafting.
Assembled Club Specifications
Playing length
Measured along the sole line from heel to butt cap with the club soled at its designed lie. Half an inch changes both swing weight and effective lie, so length is never adjusted in isolation.
Static and dynamic lie
Static lie is the angle between shaft and sole with the club at rest. Dynamic lie is the angle at impact, which is what actually determines start direction. They differ, sometimes by several degrees, and only the dynamic number is worth fitting to.
Swing weight
A balance-point measurement on the familiar letter-and-number scale, C8 through D6 for most players. It expresses where mass sits relative to the grip, not how heavy the club is. Two clubs of identical total weight can sit two full swing weight points apart and feel like different instruments.
Effective bounce
The bounce angle a wedge actually presents at your delivered shaft lean and lie, as opposed to the number stamped on the head. Leaning the shaft forward reduces it. This is the number that matters, and it is why two players with identical wedges get different turf behaviour.
Grind and sole relief
Material removed from the heel, toe or trailing edge of a wedge sole to change how it enters and exits turf. Heel relief helps an open face sit lower; trailing edge relief stops the sole bouncing off firm ground. Both are commonly ground by hand at the bench in small passes.
Which Spec Fixes Which Complaint
A rough map, not a prescription. The point is that most complaints have several possible causes and only measurement separates them.
| What You Notice | First Place We Look | Second |
|---|---|---|
| Hands ache after a round | Grip diameter and compound | Total club weight |
| Grip twists in wet weather | Compound and cord content | Build-up and core match |
| Pull that starts left and stays left | Dynamic lie | Length |
| Fat contact from tight lies | Effective bounce and sole relief | Length and lie |
| Club feels heavy late in the round | Swing weight | Shaft raw weight |
| Ballooning flight into wind | Bend profile and tip trimming | Loft and spin |
| Inconsistent face at impact | Torque against tempo | Grip diameter |
| Putts starting off line | Grip cross-section and pressure | Putter lie and loft |
See These Numbers on Your Own Clubs
A full-set spec audit measures every one of them and writes them on a card, with no fitting session required.