Tutelman -- October 20, 2007
the early 1990s, the R&D lab for TrueTemper shafts came up with
measurement tool they called ShaftLab.
Its purpose was to find out more
about how golfers bend the shaft during the downswing. It did that job
admirably. In fact, it created such a stir that TrueTemper decided to
market it to clubfitters as a high-end shaft-fitting tool. They have
indeed sold some, though it is hardly common to find one in a custom
club establishment. It is still too expensive. Also, it is
in function for the price; it is closer to cost-effective as a research
tool, which is how it started its life.
we have learned from ShaftLab. I am an engineer, and I wrote the
article from an engineer's point of view. There aren't any equations.
But if graphs throw you for a
loop, you may have trouble with it. For you, the conclusions
are stated concisely in the Executive
Summary on this page. But understanding how we come to these
conclusions will require wading
through the graphs and the physical reasoning.
- Executive summary. Just
the facts, ma'am.
ShaftLab is. How it works, what it can do, and what it can't
TrueTemper learned. In 1994, Ed Weathers of TT wrote an
article for Golf
Digest explaining what he believed ShaftLab taught us about shaft bend.
- Lessons from the data. We
can deduce things from looking at the traces, including lessons that
Weathers' article did not cover.
section simply states the lessons that ShaftLab has taught us. To learn
how ShaftLab works and how we gleaned these lessons, you will have to
read the rest of the article:
- Just about
all swings of real golfers fall into one of three profiles:
- Single peak
speed is not a reliable indicator of how much you bend the shaft.
biggest factor in shaft fitting is maximum bend of the
seems to be TrueTemper's conclusion; I'm not sure I agree with it.
shaft flex does not increase your clubhead speed.
velocity" does exist, but it isn't a very large component of clubhead
speed. For good swings (like the pros'), kick velocity is at less than
5% of their clubhead speed.
- The biggest bend during
the swing is between toe-up and lagging, and occurs sometime near the
beginning of release.
- At impact, just about every
golfer has the shaft bent with clubhead lead (shaft bent forward) and
- Bend at impact is influenced by a lot
more than just "centrifugal pull" on the center of gravity of the
is useful as a measure of shaft stiffness, but don't read too much into
it. For instance, it is not an indicator of the "free response" of the
shaft during the downswing.
- At impact, the net bend
of the shaft is nowhere near the target line.