Sensitivity is a function of the sensing device. In this case, that's the human hand. So, how does a human hand gripping a fishing rod sense things? It senses gross movement of the overall rod, and it senses vibrations along the rod. I would guess that the sensing of vibration is much more delicate (fine-grained if you will) than the detection of gross rod deflection. Therefore, a rod that transmits small oscillations at the tip down to the grip would be the most sensitive.

A very stiff or very limp rod will do a poor job of transmitting these vibrations all the way down to the grip without a great deal of attenuation. Also, a rod with lots of discontinuities (irregular taper, bulky rod guide attachments, joints, etc.) will cause the rod tip vibrations to bounce and echo, thereby damping out what is ultimately transmitted to the grip.

Of course, there are lots of other criteria I base my rod purchases on. I like light, short stiff rods that my kids can wangle around easily. I also like rods painted ruby red

Regards.

Finegrain (former physics teacher)
Woodinville