01What is carbon fiber
Carbon (graphite) fiber is an ultra‑light, high‑stiffness material in which carbon atoms are densely bonded in a hexagonal graphite crystal structure. A single filament is 5–7 μm in diameter—about one‑tenth the thickness of a human hair—but its tensile strength is roughly five times that of steel while its density is about one‑quarter. Its “strength‑to‑weight” and “stiffness‑to‑weight” are overwhelmingly high, making it the optimal material for rods that must be light yet withstand the resistance of large species.
A rod is made by winding a thin core (mandrel) with a ‘prepreg’ sheet—fibers aligned in one direction and pre‑impregnated with epoxy resin—and then heating and curing it. The fibers are laid longitudinally (0°) to provide bending stiffness, and reinforced with transverse and bias (90° ± 45°) layers to prevent torsion and cross‑sectional deformation. Rhyzome uses TORAY’s 30T full‑carbon prepreg as the standard material.
‘Carbon content’ is the proportion of fiber in the blank weight. The less resin (the higher the content), the lighter and harder the blank, but insufficient resin to bind the fibers leads to inter‑layer delamination. This is why premium rods that tout ‘full carbon’ still reinforce the bond with nano resin. A good blank is judged not by how high the content is, but by how well the increased content is sustained.
02What the tonnage (modulus) really means
In rod specs, ‘24‑ton, 30‑ton, 36‑ton’ refers not to weight but to tensile modulus (stiffness, resistance to bending)— a Japanese notation. The unit is ton‑force per mm², and 1 ton/mm² corresponds to about 9.8 GPa. Therefore 30T carbon is about 294 GPa, and 40T about 392 GPa. Values often seen online such as ‘30–45 GPa’ are at the glass‑fiber level and are not comparable to carbon.
The higher the tonnage, the thinner and lighter the blank can achieve the same bending stiffness, improving sensitivity and lightness. Thus subtle bites on the bottom are transmitted clearly to the fingertips. However, the higher the elasticity, the more brittle the material becomes, making it vulnerable to point impacts—stepping, door‑frame catches, or striking a rocky edge. brittleness— the tonnage is both a performance indicator and a weakness to manage.
This is why Rhyzome adopts 30T as the standard. 24T is soft and dull but robust, while 40T and above are sensitive and light but more demanding to handle. 30T offers a balance of sensitivity, lightness, and durability, and TORAY nano‑resin technology further mitigates the brittleness of high‑elastic carbon.
03Tonnage selection by species and technique
Olive flounder·Korean rockfish near‑shore lure — For down‑shot and jig‑head operations that tap the bottom with a sinker to read terrain and bites, a blank around 30T is standard. Both sensitivity to read bites and durability to withstand impacts on boat or rocky shore are required.
Red seabream tairaba·light jigging — When casting ‘bait’ and letting it drift to the main body, the sensitivity of a high‑elastic tip is advantageous. In the 30–40T range, a soft tip with a strong taper at the butt (midsection) is the classic design.
Yellowtail amberjack·Japanese amberjack large‑species — Big‑game that is hauled in with sudden power depends more on ‘butt power’ and blank thickness than on modulus numbers. A design that places strength in the waist outperforms a merely higher tonnage.
- Higher tonnage is always better?— High elasticity benefits sensitivity and lightness but increases brittleness, making point impacts more damaging.
- Tonnage = power (strength)?— Tonnage describes material stiffness; power (line size or target weight) is a separate specification. Confusing them misaligns the rig.
- Carbon never breaks?— While strong in bending, it is vulnerable to point impacts such as stepping or snagging, so handle storage and transport with care.