In addition to length and weight, another way fly rods differ from one another is in their action.
Loosely defined, it’s related to the flex pattern of the rod; the action and flex of the fly rod significantly affect its feel and performance. Rod actions are rated as soft, medium, and fast. Following is a rundown of each.
Most fast-action rods will be tip flex, meaning only the tip of the rod is going to bend while the butt is very stiff. These rods can be hard for the beginning angler to cast, but if you are on big, windy water and need distance, fast-action rods are for you.
A medium-action, mid-flex rod is the best all-around rod, since it will throw big flies and still give you a somewhat gentle presentation.
A full-flex, soft-action rod isn’t the greatest for distance and wind, but is the ultimate tool when it comes to getting a perfect presentation to a big fish selectively feeding. These rods are really only designed to be effective with a cast that’s 15-35 feet long; however, they are insanely fun to fish with.