What is the gear ratio of the reel?

For those who are new to fishing, there are so many different types of reels and their specifications vary that it can be difficult to choose one.

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Last time,  we looked at the names and functions of each part of a spinning reel in general, but this time, we will look at the gear ratio in more detail.

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The gear ratio is always indicated in the reel specifications. Both spinning reels and bait reels transmit power through gear-shaped parts. The gear ratio of the reel refers to the rate at which the spool rotates when the handle is rotated once.

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If you look at the widely used Daiwa Revros, you can see that the amount of line that can be wound and the gear ratio are different for each model, as shown below.

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The fishing target and method differ depending on the difference in gear ratio, but we will leave that aside for later. Generally, a spinning reel with a gear ratio of over 5.5 is called a high gear model, and a bait reel with a gear ratio of over 7.1 is called a high gear model.

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Both spinning reels and bait reels have a structure in which power is transmitted by a main gear and a pinion gear. The pinion gear is, as the name suggests, the smaller of the two large and small gears that mesh with each other. The gear ratio is the ratio of the pinion gear to the larger main gear.

spinning reel

Bait reel

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Now, let’s take a closer look at the gear ratio using a bait reel, which has a power transmission path that is easier to see with the naked eye than a spinning reel.

The model used is Shimano’s Metanium XT with a gear ratio of 6.2:1.

First, if you disassemble it, you will see the main gear and pinion gear.

The power transmission structure is such that when the main gear rotates, the pinion gear moves, and the pinion gear rotates in the opposite direction to the main gear. Furthermore, the spool rotates in the same direction and at the same speed as the pinion gear through the connected clutch.

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Looking at the number of teeth on the gears, the main gear has 74 teeth and the pinion gear has 12 teeth. If we calculate this, 74÷12=6.166, which means that one rotation of the handle rotates the spool approximately 6.2 times.

To summarize again, a gear ratio of 6.2:1 means that the spool rotates 6.2 times per rotation of the handle. Knowing this gear ratio and the diameter of the spool, you can figure out how much line is wound when you wind the handle once. The diameter of Shimano’s Metanium XT spool is 34mm, so if you calculate the value of gear ratio × spool diameter × pi based on this, you get 6.2 × 34 × 3.14 = 661.91mm.

If you look at the specs of where Shimano’s Metanium XT is sold, the maximum winding length is listed as 66cm, which is exactly right. However, the term “winding length” is a Japanese expression, which can be expressed in Korean as the amount of winding per rotation.