Kingfisher makes most Jo and staff products in many lengths but primarily two diameters: 15/16" and 1".
Wooden Japanese style Jo staff, hanbo, yawara, wooden hiking sticks and canes for martial art and self defense purposes in thicknesses close to one inch offer the best strength and speed but you may wonder: "why does Kingfisher offer two options that have so little difference?" The answer is readily apparent when you compare them in your hand - 15/16" feels decidedly thinner than 1". Your hand knows it and the math proves it: while the diameters are only 6% different, the volume of wood differs by 12%. Here's why:
At first glance, you may think 1/16" diameter change is very small. We can calculate [1-.94]/1 x 100 = 6%
The wood volume however is written as V= π(d/2)²h where d is the diameter and h is the length of the staff. Notice the term (d/2)². This means that the volume goes up exponentially as a function of the diameter. If you do the computation, you'll see that a 1" staff has 12% more material than a 15/16" staff. A skilled martial artist doesn't need to crunch numbers to make a determination and as a buyer, it's pretty easy to make a subjective decision without comparing the two physically or getting out a calculator: 1" seems medium thick - a kind of neutral diameter, not to thick, not too thin. 15/16" seems slightly thinner, faster, a little more precise. Indeed, 15/16" is the diameter of the classic Japanese Jo - the wooden staff of Japan.
While koryu (old school) staffs and the traditional Aikido jo are generally 15/16" and hikers seeking a lighter weight stick also may prefer the thinner option, 1" is better for martial artists seeking slightly more girth and mass without sacrificing too much maneuverability and speed.
Approximate weight of staffs in various wood grades
|Grade L5 15/16" diameter||.35oz per inch length|
|Grade L7 15/16" diameter||.38oz per inch length|
|Grade L5 1" diameter||.39oz per inch length|
|Grade L7 1" diameter||.43oz per inch length|
|Enhanced 15/16" diameter||.42oz per inch length|
|Enhanced 1" diameter||.48oz per inch length|