Grip core diameters refer to the inner diameter of the grip (ID) thatís the part that touches the shaft, rather than the outer diameter (OD) which is the part that touches your hands.
Most ladies are .560 which is to say that the inner diameter is .560 of an inch.
Most menís are either .580 or .600
Itís logical to assume the smaller diameter will feel smaller, but itís just the opposite as the smaller diameter has to stretch more to fit over the shaft thereby expanding the grip making it feel bigger. This of course assumes the same wall thickness on both which should be the case of the same model grip from the same manufacturer, but will vary from model to model and from different manufacturers.
In the last 5 years or so, the industry standard for shaft butt outer diameters (OD) has been .600 Prior to that time, the standard was .580. But there are also many .590 and .605 and even .610 and .615 shafts out there. Some very mainstream shafts are as much as .625 and .630.
Therefore, installing a .580 grip on a .580 shaft would be standard size, or installing a .600 grip on a .600 shaft would be standard size.
Installing a .600 grip on a .580 diameter shaft will be slightly undersize, and installing a .580 grip on a .600 shaft will be slightly oversized.
To determine what the OD of your shaft is, you could check with the club manufacturer, or the shaft company, or you could strip a grip and measure the diameter at the top of the shaft with a caliper.
You may also be able to take a measurement with your calipers just below the grip without removing it as most shafts will have an adequate parallel butt section to allow for this, however this will not be reliable because even if the shaft parallel is 12Ē and the grip is 11Ē you are not privy to how much of that butt section of the shaft may have been trimmed in the final assembly of your club.
Also there is no guarantee your shaft even started with a parallel butt section, some shaft designs have a constant taper.
This method will be most effective in the case of a stepped steel shaft where you are certain that the exposed shaft just below the grip is on the same step as the rest of the grip, and will not apply to clubs that have been cut down, say for kids.
Until next time,