Of all the different grips, the most popular one is arguably the worst one. I know. The thumb-on-top grip is advocated by some very famous fly casters. It can work with practice, and if you like it, that’s fine. At one time, I used it.
As a community, however, we have to acknowledge that the way fly casting is taught has not been very successful for most people. We have to start questioning the dogmas of fly casting, and the grip is an excellent place to start.
All grips are not equally good.
Why The Thumb-On-Top Grip Is Not Ideal: Reason #1
The thumb-on-top grip places a fatty pad on top of the handle to stop the front cast and to make back casts. To increase the grip’s efficiency of energy transfer, the caster must grip more tightly than other options. The inefficiency of a thumb-on-top grip manifests, in part, as grip fatigue, and there is no simple remedy. When the thumb is placed on top of the handle, it is difficult to find another bone or hard surface that can be placed on top of the handle (towards the butt).
Why The Thumb-On-Top Grip Is Not Ideal: Reason #2
In addition, the arm’s natural movement creates the least straight rod tip path forward and back with a thumb-on-top grip. With practice, it is possible to make the adjustment required to create a straight rod tip path, but the necessary changes are far greater than other grips.
Why The Thumb-On-Top Grip Is Not Ideal: Reason #3
One last consideration is that the thumb-on-top grip also restricts the wrist’s range of motion, arguably the most of any grip, or perhaps similar to the finger-on-top grip. Since longer casts and softer rods require longer strokes, one way to lengthen a stroke is by opening the wrist – not an option for a caster who uses a thumb-on-top grip.
Which Grip Do I Use?
The key grip, V-grip, and finger-on-top grip are variations of a bony grip – an efficient grip. When the pisiform bone is placed on the top of the handle, front casts are stopped more abruptly, back casts are made with more power, and hook sets are more immediate. I use the key grip.
Adopt the grip that you like. If you are starting to fly cast, just don’t use the thumb-on-top grip, and put your pisiform bone on top of the handle.