Launch Monitor Numbers

ApexGrind · July 24, 2007

Spin rate in particular (cpm)

Over the last few days I've been on 2 launch monitors. Few months ago I transitioned from my Hogan Apex Persimmon to a 9.5 deg 983K that someone gave me. I think the shaft is 45", titleist fujikura speeder stiff -- I assume the original shaft. My swing speed seems to be about 98 mph.

Ball speed about 135
About 14 deg launch angle

At the first place a couple of days ago the assistant pro (who seemed to know what he was doing with the launch monitor) got spin rates around 2800 to 3000 some. Today at GolfTEC inside of Golfsmith I had my fit checked by a pga certified teaching pro and we tried my driver. Again, mid to high 90's speed. I said I was interested in seeing launch monitor numbers again. I guess that part is run by Golfsmith. He said that ideally, with my swing and a 9.5 deg driver I'd want.

135-150 mph ball speed
13-14 deg launch angle
2500-2750 cpm spin rate

Well I went over to the launch monitor (run by Golfsmith guys who didn't seem to know what they were doing) and hit the above numbers except for spin rate. They were measuring 3200s, 3300s.

So both times my spin rate seemed to be on the high side (very much so at Golfsmith). How does that work with everything else being in an expected range? Is spin rate entirely a function of the club face? Is it where on the club face I'm hitting it? I'm getting the expected launch angle.

How is spin rate (if at all) independent of ball speed and launch angle using the same driver?

Dyno · July 25, 2007

I golfed with the legendary Joe Kwok recently and we talked alittle about LM numbers.....basically the spin number isn't all that reliable on consumer grade machines so one should really take them with a grain of salt. Half the machines out there calculate the spin based on whatever algorithm they use. I know with my own fittings, I concentrate on impact pattern on the face, ballspeed and launch.....the spin ends up where it ends up.

Spin is a function of effective loft at impact, launch angle and the force vector to accomplish that launch angle. Basically the smaller differential between the force vector and the launch vector.....the lower the spin. Which means you can use a lower loft to max out ballspeed. :drinks:

There's some other factors involved but they are relatively minor in comparison. A few hundred RPM is pretty inconsequential.

And the whole deal with high launch/low spin shafts I'll never understand....more launch = more spin.....according to physics anyways. But marketers dont' give a damn about physics....unless it can earn them $'s.

ApexGrind · July 25, 2007

Thanks. That is in line with what I was guessing.

(I suppose if you could design a shaft with a very low kick point that "fliped" just before impact you could achieve a high launch and low spin... :drinks:)

Dyno · July 25, 2007

Then the tip would be loose and you'd hit it all over the place. Plus the effective loft would increase thus increasing spin as well. Plus the shaft contribution to effective loft is limited by the distance of head center of gravity to centerline of shaft.