Understanding Rod Action and Choosing the Right Rod for You

The Orvis Flex Index is just one way to describe the way a fly rod performs.

Ask almost any fly fisherman to cite the differences between fast- and slow-action fly rods, and you’ll probably get some version of: “A fast-action rod is stiffer than a slow-action rod.” While, at a very basic level, this is usually the case, it’s kind of like describing the difference between a Great Dane and a Chihuahua as merely one of size. Such a description of rod action doesn’t come close to explaining the many intricacies and variables involved, nor does it explain why rod action is important to casters and anglers.

Poring over fly-fishing catalogs won’t offer much illumination on the topic, either. Different manufacturers use different terminology to describe their products, and there is no industry standard to which you can compare any one rod. Get a bunch of the industry’s top fly-rod designers together to discuss the issues, and things start to get clearer, although you’ll still hear plenty of competing points of view. Here’s a guide to understanding rod action.

Defining the Problem
It is surprisingly difficult to nail down a simple working definition of action, but it’s clear that action is not a single, physical, unchanging attribute of the rod in the same way that taper and length are. As Sage’s head designer, Jerry Siem, notes, “[Fly rods] have no action at all unless they are loaded with a line and cast.” Rod builder Alan Palmer, quoted in A.J. McClane’s The Practical Fly Fisherman (1953), saw the problem in mechanical terms:

A rod can be broken down into three convenient and easily recognized sections, the tip, the middle and the butt. In actual casting, the hand drives the butt, the butt drives the middle, and the middle drives the tip, and, of course, the tip drives the line. The tightness or looseness of this linkage is the action of the rod.

But Palmer offered no language for describing this “linkage.” And trying to define action simply as the “stiffness” of a fly rod doesn’t take into account that the relative stiffness is not uniform throughout. A rod may have a tip that is stiffer than the butt-section, for instance, and the placement of stiffness along the blank can be one of the key determiners of rod action.
However, world-champion caster Steve Rajeff, who designs rods for G. Loomis, argues that—even if all the parts aren’t, in fact, equally stiff—a fly rod does have an overall feel that makes one rod feel stiffer than another. He sees rod action, then, as a combination of taper (“which determines where the rod bends”) and stiffness (“how much it bends”).

Orvis’s Jim Lepage, a trained engineer, at first struggled with the notion of defining rod action in non-scientific language, but he ultimately settled on two terms, flex and recovery rate, which correspond loosely with Rajeff’s taper and stiffness. (A rod’s recovery rate is the time it takes to return to straight after it has been bent, which is somewhat a function of stiffness.) The Orvis Flex Index, which the company developed in the mid 1990s, describes the speed and amount of power required to make a rod bend to a predetermined load, and it allows Lepage to assign a numerical value between 2.5 and 12.5 to a specific rod action. The higher the number, the faster the rod action.

Getting the Bends
Back when most rods were made of bamboo, their actions were described in more varied terms—mostly because there was so much more variation in the rods themselves, even those from the same maker. In addition to discussing a rod’s speed, anglers talked about its smoothness or crispness or power. A bad rod was sluggish or whippy or tip-heavy. You could order a rod with a “dry fly” action or “wet fly” action, or you could invent your own. There was even something called a “double” action, in which the caster could supposedly feel two distinct “power impulses” during the cast. In the years just after World War II, “parabolic action” rods were touted by the likes of A.J. McClane in the pages of Field & Stream.

Today’s advanced materials and technology have taken a lot of the guesswork—and thus a lot of the variability—out of replicating rod action, even across wide ranges of rod lengths and line weights. But designers are faced with many of the same options for achieving a particular action. A graphite fly rod blank is a hollow tube that tapers from a thick butt to a thin tip. The amount of energy required to bend that tube at any one spot is governed by its diameter (determined by the taper), as well as the strength and thickness of the material. (Thanks to advances in technology, guides, ferrules, and finishes play less of a role than they did in the past.) The manipulation of any of these components produces a different action.

Almost every rod on the market today features a progressive action, which means that the rod bends deeper into the blank at a consistent rate as pressure is increased (as you apply more energy and increase mass by casting more line). This is not to say that all modern fly rods are the same, however. Plenty of craftsmanship, personal taste, and old-fashioned trial-and-error go into the creation of a new fly rod. For instance, Sage’s Siem says he likes to start from the tip of the rod and “work [his] way from the steering wheel and the brakes down to the engine.” Lepage, on the other hand, says he doesn’t even wiggle a rod until the prototype tests within the parameters set by the Orvis Flex Index; but then the fine-tuning process is purely subjective, based on the rod’s performance at the casting pond.

Speed Limits
Although wholly inadequate as a way to describe how a rod will feel in your hand, the “rod-speed” scale does tell you something about how a rod might perform. The terms “fast,” “medium,” and “slow” refer to how fast the rod bends and recovers. Siem notes that this translates to casting tempo: “A fast-action rod loads and unloads faster, and a slow-action rod loads and unloads slower.” Of course, one of the main problems with this system is that these descriptions don’t answer the question “in relation to what”?

This begs the question Why isn’t there some kind of standard for measuring this? In the 1980s, both Mel Krieger and Scott Fly Rod founder Harry Wilson called for the creation of a rod-action rating system, but there wasn’t much support for the idea. A decade later, Orvis came up with the Flex Index and offered it to the industry for other companies to adopt, but none did. There is not enough agreement among manufacturers and designers about how to measure action, how to apply the terminology uniformly, and how to enforce any standards. Lepage argues that the Flex Index would work well as a base for ensuring consistent measuring of action while still leaving enough “wiggle room” for designers to individualize their products.

Loaded Terminology
So what can we tell from the current terminology? A fast-action rod bends mostly at the tip—which is why Orvis refers to its faster rods as “Tip Flex”—and recovers more quickly than slower rods. Medium-action rods bend more toward the middle of the blank, which is more comfortable for many casters. Slow rods bend all the way into the butt section, which makes the smoothness of casting stroke crucial but tends to be more forgiving in terms of timing.

But keep in mind that these descriptions hold true for a given line weight at a given distance; designers make an educated guess about how most anglers will use a particular model. Changing the line weight or speed can change a rod’s action dramatically. Put a 6-weight line on a 5-weight fast-action rod, for instance, and the rod bends deeper into the blank.

Starting in the mid 1990s, the fly-fishing market was inundated with fast-action rods, and a “modulus war” broke out as companies touted their new high-tech materials as the key to higher line speed and more power. According to Rajeff, fast-action rods are so popular because of simple human psychology. “We all want to go faster,” he says, whether we’re driving, or running, or fly fishing. “There’s a misconception that ‘fast’ is better,” Scott president Jim Bartschi argues, “but that’s not always the case. I don’t want my 4-weight dry-fly rod to be stiff.” By abandoning such loaded terminology, Orvis has trained its customers to look beyond value-based terms to focus the rod itself, Lepage says, and the company sells twice as many Mid-Flex 5-weights as it does Tip-Flex models.

While there are still small disagreements among experts about the advantages and disadvantages of each particular rod action are still somewhat up for the debate, there are some fundamental truths. A fast action generally makes a rod load quicker and makes it easier to produce tight loops with high line speeds, which for many casters translates into longer casts and the ability to cut the wind better. Plus, you can makes casts faster when you’re casting off the tip. That’s why fast-action rods are so popular on the bonefish flats. But there’s a trade-off: the caster doesn’t feel the rod loading and unloading well, which can make the precise timing required by a stiff rod difficult for novices. The fast recovery rate can also snap very light tippets, leading to more broken-off fish.

Medium-action rods work well for a wide range of applications—if you’re going to be switching from nymphing to dry-fly fishing off and on during the day, for instance—so if you’re only going to have one rod, a medium action is a good choice. Many anglers find they can cast more accurately with a medium-action rod, as well, because there’s more time during the stroke to line everything up. For casting sinking-tip lines or large flies, a medium-action rod easily throws a more open loop, and it works better for roll-casting. If you really need to throw tighter loops, you can underline the rod by one line weight.

Slow-action rods are definitely the smallest part of the market. For repetitive roll-casting or throwing small flies short distances on long leader, you can’t beat a slow-action rod, but Bartschi also notes that his favorite sinking-line rod is a slow rod with a stiff tip, which performs roll-cast pickups well and throws a slow open loop. Slow rods require smooth acceleration and greater tip control during the casting stroke, so some casters struggle with tailing loops.

Because action and casting stroke are interrelated, an accomplished caster can cast well with any action. The truth is that power and strength are not related to rod action. For instance, depending on your particular stroke, you may be able to cast farther with a medium-action rod that you can with an ultra-fast model.