Butt CPM Belongs on the Work Order
A cycles-per-minute figure only means something once somebody writes down the clamp length, the head weight, and the date beside it. Otherwise it's a number nobody can use.
Filed under Butt Frequency · 6 minute read
A golfer walked in with a printout from another shop showing his 7-iron reading at 292 cycles per minute. He wanted to know whether that was too stiff. There's no honest answer to that question from the number alone, and it took a few minutes at the counter to explain why.
A Number Without Context Isn't a Number Worth Trusting
Butt CPM is a measurement of the assembled club, taken by clamping the grip end, deflecting the club, and counting how fast it oscillates back to rest. Change the clamp length by even half an inch and the reading moves. Swap the head for one a few grams heavier and the reading moves again, with nothing about the shaft itself having changed at all.
His printout had a number and nothing else — no clamp length, no head weight noted, no date. That number is not useless, but it can't be compared against anything with confidence, including a reading taken here on a different clamp with a different assumption baked in. Two shops can both be measuring correctly and still produce numbers that don't line up, simply because neither wrote down how they got there.
A CPM reading by itself tells you almost nothing. A CPM reading with the clamp length and the date next to it tells you whether anything has actually changed.
What Goes on Our Work Order
Every butt frequency reading we log carries four things alongside the number itself:
- Clamp length used, since it's the single biggest source of reading-to-reading disagreement
- Head make and weight, because mass at the tip shifts the whole system
- Grip model and build-up, since weight and clamp compression at the butt affect the number too
- The date, so a reading taken today can be honestly compared against one from a year ago
None of that is complicated. It's the difference between a number that means something in five years and a number that's already meaningless the day after it's written down.
Why We Bother
The value of writing all of it down shows up later, not on the day of the build. A golfer who comes back after a regrip wanting to know if anything changed can only get a real answer if the original reading has enough context to compare against fairly. Without the clamp length and the grip notes, a shift of a few cycles could mean the shaft moved, or it could just mean the new grip compresses differently under the clamp. Those are very different problems, and only the paperwork tells them apart.
We told the golfer at the counter the same thing: bring the club back, we'll read it on our clamp with our conventions written down, and from that point forward every future reading will actually mean something against the last one. That's a more useful answer than trying to argue with a number that arrived alone.