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Quads vs Hex Bamboo Rods

February 21, 2010

4/5wt hollowbuilt quad

hollowed strips

It is often argued that quads (4 strip bamboo rods), are better than hexes (6 strip). This is my take on it.

I don’t think one rod section is necessarily better than another for all applications. Choice of rod really depends on the type of fishing you do and what you want in a rod. Different rods have different advantages/disadvantages in different situations.

In purely engineering terms quadrate section rods have one distinct advantage over hexes (and circular sections) – they have a higher moment of inertia. What this essentially means is that they are stiffer per the same cross sectional area. By extension this means that you can theoretically get the same stiffness, and thus ‘same’ rod action in a square rod as you can in a hex but using slightly less material (approx 5% less). Quadrates therefore weigh less than hexes (and circular sections) per the ‘same’ action . I say ‘same’ because there is somehow a subtly different feel to the quad. I think this results from the different distribution of  powerfibers relative to the neutral axis of the rod. The difference in feel is difficult to quantify or explain in scientific terms. Many rod designers look at stress curves as well as deflection curves to assess rod designs. It is  not possible to have a hex rod and a quad with the same stress curve AND deflection curve. Perhaps therein lies some clue to the difference in feel.

It is often claimed that quads are more directional in casting. This is in fact not the case unless the quad is rectangular. Symmetrical polygons such as hexes, circles, and squares, bend equally in all directions – even across the corners.

A rectangular quad section is another whole kettle of fish. Here you do get the directionality depending on the orientation of the rectangle. Obviously with a rod, it must be wider than deep or it would twist when casting. i.e. the guides must be mounted on the wider flats. A rectangular rod offers  a great advantage in terms of accuracy. It tracks very true and enables pinpoint accuracy casts. This advantage is in some part tempered, however, by the fact that rectangular quads, due to their directionality, are lousy roll casters. You can overcome this to a degree by rotating your forearm with your wrist to ‘follow’ the rod, but it is less than ideal.

Perhaps the greatest advantage of a rectangular quad is that you can get the stiffness you need out of a rod – by making it wider – but still allow it to bend the way you want it to – by keeping it thin. This provides great design flexibility. It is also why the fastest possible rod you can theoretically make, for any given weight of material, would have to be rectangular in cross-sectional profile – hollowed.

How does this work?

Essentially a fast rod can be described as bending tightly in the tip and not much in the butt. So, how do you get something to bend tightly without it breaking? The answer is by making it thin – think of a piece of paper for example. The problem with thin tips however is that they can bounce/wobble and in so doing impart unwanted waves to the line. Ideally you want the tip to recover fast to its original position. To do so the tip has to be stiff. So how do you make it stiff? The obvious way is by making it thicker. But then you are caught in a vicious circle where you have to compromise on the rod’s ability to bend in order to maintain the stiffness required.

Luckily there is another way to increase stiffness – by increasing the width. Whilst widening a section to increase stiffness would not be an efficient solution for most structural applications , in rodmaking it has its place. Widening the section, whilst still keeping it thin allows one to achieve a desirable stiffness without compromising on the desirable bending. This is the principal on which the maverick rodmaker Mike Montagne built his rods. I have built rectangular quads based on this principle and they are indeed very quick. Definitely the way to go for a stillwater rod especially if hollowbuilt as well.

Why are quads not often seen?

Quads are probably generally less common simply because they are more difficult to make. The corners have more acute angles than hex (45deg vs 60deg) requiring more careful planing and handling. One also has to have 2 sets of planing forms, one for each side of the strip. This is because the rod strips are isosceles triangles rather than equilateral. You never profile the strips by planing the enamel side of the bamboo so you therefore can’t flip the strips in the same groove like you can with hex.

I  am now making quads in addition to hexes, not only because they offer the advantages outlined above but also because I personally really like the look of them. For people who enjoy faster actioned bamboo rods they are definitely the way to go. That said, I would not say they are superior in and of themselves. For many situations a slower action rod is more desirable and the weight saving you can get by building it in quad format rather than hex would not necessarily be a distinctive consideration. Where it is a consideration quad is the way to go.

One Comment leave one →
  1. August 5, 2013 9:24 am

    Your style is really unique compared to other
    people I’ve read stuff from. Thanks for posting when you’ve got the opportunity, Guess I will just
    book mark this site.

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