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Fitting parameters, explained.
The specs that actually move your numbers, in plain language, with two worked examples from my own bag.
The specs on a build sheet
Roughly in the order I fit them. Each one is a lever; the job is to find which levers your swing needs.
Length
Length sets how far your hands are from the ball and where the club bottoms out. Too long and strike moves toward the heel and contact gets inconsistent; too short and you hunch or reach. I start from wrist-to-floor and height, then confirm with strike location on the face. Centred contact beats extra length almost every time.
Lie angle
Lie is the angle between shaft and sole at address. At impact it decides whether the face points where the loft sends the ball. Toe-down and the ball tends to start right; heel-down and it starts left, more so with more loft. It has to be checked dynamically, because shafts bow toe-down during the swing. My own lie-angle lesson is a good warning about chasing a static number.
Loft and gapping
Loft is the biggest single control on launch and spin, and it is what makes the distance steps between clubs. There is no standard loft for a given iron number, so I fit by the carry gaps, not the stamp on the sole. Even gaps matter more than any single club going far.
Shaft weight
Weight is the shaft spec most players feel. It changes total club weight, tempo and timing. Too light and the swing gets quick and loose; too heavy and speed and height drop late in a round. I pick the weight before the flex.
Flex and bend profile
Flex labels are not standard between brands. What matters is how stiff the shaft is along its length versus how forceful your transition is, your tempo and when you release the club. Those decide launch and feel more than the letter on the label.
Torque
Torque gets talked about a lot but it rarely decides a fit by itself. I treat it as a feel and fine-tuning spec once weight and profile are right.
Swing weight and MOI
Swing weight measures how heavy the head feels; MOI measures how hard the club is to swing around your body. Matching every club on one of them keeps the feel consistent through the set. My current irons are MOI-matched.
Grip size
Grip size affects comfort, grip pressure and how freely the hands release. Too small and many players over-squeeze; too big and the release can stall. It comes from hand and finger measurements, then feel.
Head design
Head size, centre of gravity and forgiveness decide how much ball speed and direction you keep on off-centre hits. Higher-MOI heads lose less on mishits. The head usually matters more than the shaft for distance and accuracy.
Set makeup
Which clubs are in the bag at all. The long end and the wedge end are where most sets have holes or overlaps, and gapping shows both.
Reading the launch monitor
The specs change the club. These readings tell you whether the change worked.
- Ball speed and smash factor. Smash is ball speed divided by club speed. It is the quickest read on strike quality. Drivers top out around 1.50, irons lower.
- Launch and spin. Together these decide height and carry. Each club has a window that suits your speed; outside it you lose carry or control.
- Attack angle and dynamic loft. How steeply the club arrives and how much loft it delivers. The gap between them, spin loft, drives spin.
- Face, path and face-to-path. The face mostly sets start direction; face relative to path sets curve.
- Dispersion. How wide shots finish, short to long and left to right. The clearest sign of whether a change helped.
Worked example 1: finding the gaps in my own bag
From my August 2026 distance model, the stock carry steps through the irons are tight: 11 to 13 yards from 9 iron to 5 iron. The wedges are not.
| Step | Stock carry | Gap |
|---|---|---|
| SW → GW | 83 → 102 | +19 |
| GW → PW | 102 → 122 | +20 |
| PW → 9 iron | 122 → 139 | +17 |
| 9 iron → 8 iron | 139 → 152 | +13 |
| 3 hybrid → 5 wood | 197 → 228 | +31 |
What I read from it. Two 19 to 20 yard holes at the scoring end, where I need the most precise numbers, and a 31-yard hole at the long end. The irons are fine. The fit question is wedge loft spacing and whether a club between the 3 hybrid and 5 wood earns a spot more than one of the wedges does.
Source: my distance model, built from usable full swings with recency weighting. See the Data Lab for the full table.
Worked example 2: reading my driver numbers
| Reading | My stock value |
|---|---|
| Club speed | 108.1 mph |
| Ball speed | 150.7 mph |
| Smash factor | 1.42 |
| Launch | 13.7° |
| Spin | 2,574 rpm |
| Attack angle | +1.7° |
| Stock carry / middle 50% | 252 yd / 240–299 yd |
What I read from it. Hitting up on the ball, with mid-teens launch and spin in the mid-2,000s, is a sensible window for about 108 mph, so I would not change loft or shaft to chase launch. The weak points are strike and spread. A 1.42 smash leaves ball speed on the table, and the middle half of my drives spans 59 yards of carry. For this driver, the fit work is about centred contact (length, head forgiveness, shaft weight and feel), not launch.
Want to go further? The member course Fit Your Own Clubs walks through each spec with worksheets. It is in development.
Numbers on this page come from my own clubs and launch-monitor sessions (distance model updated August 2026). The explanations are my own summary of standard clubfitting practice, as I apply it at SnowBird Sports.