One of the questions I’ve been receiving lately is different shaft bend profile data that different shaft companies give.
For instance, Miyazaki shafts use what they call an ‘International Flex Code’ for their shaft bend profiles. Here’s an example
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Let’s look at the first shaft on the list, the Kusala Black 83, X-Stiff Shaft. It has an ‘international flex code’ of 5689.
What it is measuring is the stiffness of the shaft at different parts of the shaft. The first number is the butt end of the shaft. The last number is the tip end of the shaft. The higher the number, the stiffer that part of the shaft is.
Take a look at the Miyazaki Web site to get a better idea.
So, ‘3’ is considered ‘regular flex’, 5 is a ‘stiff flex’, 7 is X-Stiff and 9 in XX-stiff.
Thus, by judging the Kusala Black 83 X-Stiff shaft with an International Flex Code of 5689, the butt end of the shaft is ‘stiff’ and so is the mid section and the tip end is extremely stiff.
From what we know about shafts, the stiffer butt end of the golf shafts are designed more for very aggressive and hard swings. The stiffer the tip end of the golf shaft, the lower the ball will initially launch off the clubface.
So with the 5689, it’s supposed to be designed for golfers who generate a good amount of clubhead speed and have no issues getting it up in the air, but do so by having a slower, non-aggressive transition.
John Senden (116 mph clubhead speed) would probably fit more into this type of shaft.
But, we do have a problem with this International Flex Code. Since it’s Miyazaki’s measurement, we can only compare the shafts that Miyazaki has measured with it.
Let’s say you want a shaft with a similar bend profile to Miyazaki’s, but more torque. If you can’t find the torque and bend profile match, the International Flex Code is useless.
That’s what we are starting to see with more shaft manufacturers, their own version of bend profile measurements. But, if you find the shaft bend profile you want…but don’t like the torque or the weight, etc…then you will need to find a way to figure out what other company’s shafts have a similar bend profile and the other characteristics that you want.