You're looking at a tenkara rod spec sheet and you see "6:4" or "7:3". You nod as if you understood. Deep down, you have no idea. You're not alone: even within the tenkara community, this rating system creates more confusion than clarity. This article will give you a deep and practical understanding of what these numbers mean, and — more importantly — how to pick the action that fits your fishing.
Where does this Japanese notation come from?
When tenkara arrived in North America in 2009 (Daniel Galhardo, Tenkara USA), there was a need to translate a Japanese rod rating system that Western anglers found alien. Classical fly rods were described with adjectives: fast, medium, slow. Subjective, imprecise, but familiar.
The Japanese use ratios instead. The logic is elegant: imagine the rod divided into 10 equal sections from grip to tip. The ratio tells you where the main flexion begins when you load the rod. The first number = the stiff part (butt side), the second = the flexible part (tip side).
- 8:2: rod bends at 20% from the top. 80% stiff, 20% flexible. Tip-flex.
- 7:3: rod bends at 30% from the top. 70/30. Medium-fast.
- 6:4: rod bends at 40% from the top. 60/40. Medium / mid-flex.
- 5:5: rod bends at the middle. Loads progressively along the entire length. Slow / full-flex.
The bigger the second number, the more flexible the rod. The smaller it is, the more tip-stiff the rod but loading deeper.
The fundamental trap: action is not power
Here's the most common error: believing that a 7:3 rod is stronger than a 5:5 because it's stiffer. Wrong.
The ratio describes where the rod bends, not how much force it takes to bend it. Tom Davis (Teton Tenkara) documented this problem with his Rod Flex Index: you can have a full-flex rod (5:5) that's very stiff (requires a lot of force to bend) AND a tip-flex rod (7:3) that's very soft (bends easily). The ratio says nothing about raw power.
Worse: the notation isn't standardized between manufacturers. Chris Stewart (TenkaraBum) spent years denouncing this problem. A Daiwa 7:3 doesn't behave like a Nissin 7:3 or a Tenkara USA 7:3. Stewart even developed his Common Cents System (10-penny bend test) to objectively compare rods.
Practical consequence for you: trust the ratio as a general indicator, but read reviews before buying. A 6:4 from one maker might be equivalent to a 7:3 from another.
The four actions, in detail
5:5 — Full flex / Slow action
The rod loads along its entire length. Bends like a wedding bamboo whip. The most traditional, the most Japanese, the most purist action.
Feel: very smooth, almost hypnotic. Slow, fluid casting. Fighting a fish becomes sensorial: you feel every vibration, the rod bends fully even on 10-inch brookies.
Pros:
- Maximum protection of fine tippets (6X, 7X, even 8X)
- Spectacular fights: the rod absorbs head shakes
- Natural sasoi animation — vibrations transmit softly
- Forgiving for beginners: timing errors are absorbed
Cons:
- Poorly adapted to windy conditions — the rod doesn't return enough power
- Fighting large fish (15"+) is very slow, risking exhaustion of the catch
- Long-distance casts are limited
- Requires some experience to control the rod at the start of the cast
For whom: intimate mountain streams, native brook trout on the Canadian Shield, experienced anglers prioritizing sensitivity, purist Japanese-style tenkara practitioners.
6:4 — Mid flex / Medium action
The most common action in traditional Japanese tenkara. The rod bends at 40% from the top, keeping 60% stiff to transmit power. It's the balance point.
Feel: precise and responsive without being harsh. You feel the rod work progressively. Casting timing is more permissive than a 7:3. Force return is sufficient for quick hooksets.
Pros:
- The universal buy — covers 80% of tenkara situations in Quebec
- Real versatility: from creek to medium river
- Moderate wind tolerance
- Good 5X-6X tippet protection
- Available in nearly all serious models (Daiwa Enshou LL36SF, Nissin Pro Square, Tanuki XL, Suntech Field Master 39)
Cons:
- None specifically — it's a smart compromise
- Lacks the extreme "personality" of a purist 5:5 or a tip-flex 7:3
For whom: your first tenkara purchase. Intermediate anglers wanting one rod for everything. Variable conditions (changing wind, variable fish size, variable stream type).
7:3 — Medium-fast action
The rod bends at 30% from the top. 70% remains stiff. This is the action of "modern" tenkara rods, often appreciated by anglers coming from Western fly fishing.
Feel: nervous, precise, fast. Casting loops form instantly. Hookset is immediate. The rod transmits exactly what it sees, without damping.
Pros:
- Excellent wind penetration
- Long-distance casts easier
- "Western" casting feels more natural for former traditional fly anglers
- Effective fighting of larger fish (landlocked salmon, 14"+ rainbows)
Cons:
- Less forgiving — timing errors create "splats" that spook fish
- Higher risk of breaking a fine tippet (6X and finer)
- Less "purist tenkara" feel
- Less natural sasoi animation — vibrations transmit too sharply
For whom: larger rivers, frequent windy conditions, rainbow or landlocked salmon fishing, anglers coming from classical fly fishing seeking a smooth tenkara transition.
8:2 — Tip flex / Very fast action
The rod only bends in the top 20%. The rest remains essentially rigid. An extreme action, rare in classical tenkara.
Feel: very precise, almost surgical. Lightning-fast hooksets. The rod acts like a stick for 80% of its length, with a sensitive tip whip on top.
When to use it:
- Sustained strong-wind conditions
- Casting weighted flies or small streamers (rare in tenkara, but possible)
- Deep-water fishing with heavy beadhead kebari
- Very experienced angler with millimeter-perfect timing
Honestly: few authentic Japanese tenkara rods are 8:2. It's more typical of keiryu rods (Japanese bait fishing) or hybrid rods. If you see a tenkara rod advertised as 8:2, be skeptical — it's likely marketing exaggeration or a very specialized rod.
Decision table: which action for what?
Here's the decision grid I use after ten years of experience:
- First tenkara purchase, I want one rod only: 6:4 at 3.6m. Period.
- I mostly fish small brookies in intimate streams: 5:5 or 6:4 at 3.3m, with 6X-7X tippet. Maximum fun on small fish.
- I fish the Canadian Shield, variable conditions: 6:4 at 3.6m, 5X tippet.
- I fish medium-to-large rivers, sometimes windy: 7:3 at 3.6m or 3.9m, 5X-4X tippet.
- I target 14-18" rainbows: 7:3 at 3.9m or 4.0m, 4X tippet.
- I want to try tenkara for Atlantic salmon: reinforced 7:3 at 4.5m, 3X tippet. (See also our dedicated article on tenkara for Atlantic salmon.)
The "progressive action" myth
A common myth: "I start with a 5:5 to learn, then I evolve to a 7:3 when I get better."
False. Many experienced tenkara anglers — Jason Klass from Tenkara Talk among them — observe the opposite evolution: novice anglers appreciate stiff rods because they resemble what they know; with experience, they migrate toward softer rods because they offer more sensitivity and purer loading. "Quality casting comes from constant loading and slowing down," writes Jason. "Softer rods are better suited to this style."
In short: there's no hierarchy. Each action has its terrain. The best anglers often have a 5:5 AND a 7:3 in their arsenal, for different occasions.
And length? The hidden factor
Action is only half the equation. Length radically changes rod behavior:
- 3.0-3.3m: compact rod. A 7:3 here feels like a 6:4 at 3.9m.
- 3.6m: standard length. The baseline for comparison.
- 3.9-4.5m: long rod. A 5:5 at 4.5m feels very different from a 5:5 at 3.3m — the self-weight amplifies all phenomena.
Tom Davis's Rod Flex Index (RFI) tries to capture this length/action interaction: RFI = (weight needed to bend the rod) / (length in meters). Under 3.5 = full flex, 3.6-5.5 = mid flex, 5.6-6.5 = mid-tip, 6.6-8.5 = tip flex. More precise than the Japanese ratio, but requires measurement.
Conclusion: keep it simple
After all this analysis, here's my pragmatic recommendation:
- For your first tenkara rod: a 6:4 at 3.6m. The universal buy that won't disappoint you.
- For your second rod, in 6-12 months: add a complementary option. If your first is a 6:4 at 3.6m, get a 5:5 at 3.3m (creek specialist) or a 7:3 at 3.9m (large-river specialist).
- Don't fall into "ratio chasing" — what matters is fishing, not collecting.
Tenkara is the art of simplicity. And simplicity, ironically, often begins with accepting that four different actions exist — and that just one will be enough for 80% of your outings.
Sources and further reading
- Chris Stewart, TenkaraBum — "What is a 7:3?"
- Jason Klass, Tenkara Talk — Tenkara Rod Action explained
- Tom Davis, Teton Tenkara — A Treatise on Static Rod Testing
- Paul Gaskell, Discover Tenkara — Tenkara Rod Facts