| Well, if you keep the thumb in the back, then it's easier to keep (perpendicular to the fretboard) pressure on the strings.
On the other hand, if you hook the thumb around the top of the neck, you can get more leverage for bending. In this situation, don't just let the thumb sit there, use it to "squeeze" your thumb and bending finger together, so the bending finger doesn't have to do all the work. Also, in this position, you don't want to just keep your wrist the same and move your thumb, or it'll be really uncomfortable. You've got to rotate your wrist/arm about 45 to 90 degrees, and then bending is kind-of a doorknob twisting motion. |