# FM Charts

NOTE 5: I was curious about the Brunswick fitting charts and wondered what the FM numbers meant. If you look at the chart you notice that the lines all have exactly the same slope and are all evenly spaced, that is the 4 line is the same number cycles displaced from the 5 line as the 5 line is from the 6 etc. It was apparent that the entire set of lines could be expressed as one simple equation. The equation defines the slope of the line and at what theoretical length the frequency would equal zero. The FM number simply displaces one line to the next. The equation I derived from picking a few points off of their chart is.

CPM = 567.5 + 10xFM - 8.54xLength

This indicates that one equation defines the entire chart. This approach has a certain amount of elegance to it and gets rid of the very subjective terms: stiff, regular etc.

The chart supplied with the Club Scout is based on published industry averages for shafts labeled X, S, R, etc. Is this better than the Brunswick chart? I have no idea. With people advocating flatlining or 2 cpm per club slopes who knows which is best. Any opinions?