Let's say the (working) limb thickness is 3/4" for a given bow. The handle will be made 1½" thick. That is twice the thickness of the limb. Since the thickness leads to stiffness to the power of three (physics), the doubled thickness leads to 2x2x2 is eight times the stiffness. So a handle width of 1/8th of the limb width is enough to achieve the same stiffness (a working handle) as the limb. By making the handle a little wider than 1/8th of the width of the limb, you will get a stiff handle. That really isn't a lot now, is it? 1/8th of the limb width... For a 2" wide flatbow that would be only ¼" wide handle! So that would be the sensible limit. But how sensible is a handle that measures ¼" wide? Not so much...
