Shimano Thunnus CI4 Spinning Reel Review

Shimano Thunnus CI4

Shimano Thunnus CI4 Spinning Reel

Rating: 4.7/5

Gear Ratio




Shimano’s Baitrunner System is undoubtedly what makes the Thunnus CI4 one of the best spinning reels you’ll ever see. Together with its Hagane Gear, Dyna-Balance, Propulsion Line Management System, SR Concept, Fluidrive II, and Super Stopper II mechanisms, the Baitrunner System makes for a superb fishing experience regardless of conditions and skill levels.


Depending on the model, the Shimano Thunnus CI4 can be quite heavy with the heftiest model weighing in at 27.7 ounces, although this is still very lightweight considering you can reel in the really big ones with its max drag rating of 25 pounds. You can always choose the lighter version at 12.7 ounces, though.



Shimano is best known for its superb engineering and space age technology in coming up with the best, the most stylish, and most technologically advanced cycling components to produce some of the fastest bicycles in the world. This technical competence has been effectively spread into the world of fishing.

Shimano Thunnus CI4 Spinning Reel 2

In fact, they are lauded as being the best when it comes to the design and fabrication of fishing reels, lines, rods, lures, and other gadgets and gizmos that have made the life of an average angler more like the pros.

The Shimano Thunnus CI4 Spinning Reel carries on with the long tradition of this Japanese industrial stalwart of creating truly superb fishing gear and accessories.

The Thunnus CI4 boasts of a variety of superior technologies including a unique Propulsion Line Management System, a patented Hagane Gear that is guaranteed to provide absolute fishing pleasure, and a superb Fluidrive II and Dyna-Balance technologies for excellent retrievals.

It even has a patented Super Stopper II technology which helps eliminate the dreaded back-play while giving you amazing power in setting up your hook. What’s really amazing is Shimano’s famed Baitrunner system. This technology gives you unprecedented performance every time you cast your line.

Main Usage

The Shimano Thunnus CI4 is designed for saltwater fishing whether you’re on your boat off the coast of Florida or even in the Caribbean or standing by the shoreline and casting your bait across the surf. Saltwater fishing offers a variety of technical challenges that may not be present in other types of fishing like those in lakes and rivers as well as the flats.

There’s just a lot of factors that you’d have to consider to help guarantee that you’ll be landing that prized fish. This is where the plethora of technological features of Shimano’s Thunnus CI4 comes in.

Shimano Thunnus CI4 Spinning Reel 3

With a legendary drivetrain providing you the confidence you need to reel in the big catch, the Thunnus CI4’s auto-return Baitrunner system gives you the experience of a lifetime.

With better castability, less friction on your line, better and improved line lay, more comfortable grips, less incidence of backlash, and a superb max drag settings the Thunnus CI4 is simply the best reel for the job especially if you’re going to head out and meet the mighty fighters and jumpers of the ocean. And with a fully swappable reel handle, it should be great for both right- and left- handed anglers.

Product Features

New and Improved Spool Design:

Combined with its amazing Baitrunner System, the Thunnus CI4 can provide an excellent retrieve at 30 to 37 inches per crank, besting even some of the more expensive spinning reels in the market. Part of this is in the new and improved spool design which boasts of Shimano’s Propulsion Line Management System.

The new spool lip design allows for greater casting distances making it ideal for surf casting. The design – made from 3D models, extensive computer simulations, and stringent tests – also helps prevent the formation of wind knots and backlashes giving you a pleasant fishing experience.

Superb Baitrunner Drag System:

The Baitrunner drag system of the Shimano Thunnus CI4 is well-known for its unparalleled efficiency especially when it comes to live bait spinning.

It provides for an amazing fishing adjustability that remains, up to this very day, unbeaten. Regardless of the type of bait you are going to use, you can rely on the Baitrunner’s superbly smooth stopping power so you’ll have the aquatic beast at the tip of your hook well in the bag.

Shimano Thunnus CI4 Spinning Reel 4

The Baitrunner also gives you unprecedented versatility whether you’re in the Bahamas or even just off Florida. You’re guaranteed to hook the fish of your dreams.

State of the Art Hagane Gear:

At the heart of the Shimano Thunnus CI4 is the Hagane gear which is the culmination of many decades perfecting the gears of performance cycling beasts.

Shimano Thunnus CI4 Spinning Reel 5

Fabricating the Hagane is the work of cutting edge cold forging technology that clearly elevates the level of durability and strength of the entire drive system. The cold forging technology does away with cutting to produce the teeth of the Hagane drive gear. Using only the latest in additive manufacturing, the company is able to produce a drive gear that is guaranteed to provide long-lasting smoothness of operation.

10x Corrosion Resistant Bearings:

With 6 ball bearings and 1 roller bearing, the ARB type of stainless steel bearings of the Shimano Thunnus CI4 give it superb corrosion resistance. Shimano’s tests reveal that these specially treated bearings can resist rust formation for up to 10 times longer compared to your average ball bearings made of standard stainless steel.

The superb corrosion resistance of the Thunnus CI4 help extend its lifespan so you get to enjoy fishing in the high seas or even from the surf regardless of your skill level. Never again will you have to worry about replacing your reel.


There’s so much to love about the Shimano Thunnus CI4. In fact, the issue on its weight is more of a personal matter. For the serious anglers, they have always relied on the technological proficiency of Shimano.

The Thunnus CI4 is rich in space age technological features that are designed with just a single purpose in mind: to help bring the joys of saltwater fishing to everyone regardless of where their favorite fishing spot is or how well-versed they are in the world of fishing.

Shimano’s unparalleled understanding of the design and fabrication of performance parts make the Thunnus CI4 simply the reel for the modern-day angler.

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