In order to explain the gear ratio as it applies to fishing reels, it’s necessary to understand the basic principle of a gear-drive system. An automobile transmission has a series of gears that dictate how fast the drive shaft turns when the accelerator is pressed. With a fishing reel, turning the handle on the reel engages gears that turn a shaft on the spool. The faster the handle is turned, the faster the spool rotates.
Turning the handle on a fishing reel engages a flat, circular spur gear, that resides on the internal shaft of the handle. Teeth on the spur gear are precisely machined to interact with a smaller gear that resides on the center shaft of the reel spool. In most reels this is a helical gear, which is shaped like a small, hollow barrel. Disengaging the free spool lever shifts the spur gear away from the helical gear, which allows the spool to rotate freely when casting. Engaging the lever shifts the spur gear back into position where it interlocks with the helical gear.The diameter of the spur gear and helical gear are proportionate to the gear ratio of a particular fishing reel.
A basic gear ratio is one-to-one--or 1.0.1--which is the standard numerical specification for fishing reel gear ratios. With this ratio, one turn of the handle produces one rotation of the spool. Considering the average circumference of a full spool of line is approximately 6 inches, 1.0.1 ratio would require 60 turns of the handle to recover 10 yards of line onto the spool.
A low gear ratio on fishing reels provides torque, but little line is recovered with each turn of the handle. An high 10.0.1 ratio would recover line rapidly, but without ample torque to fight sizable fish. The optimum gear ratio for fishing reels accounts for power and the recovery rate of fishing line.
Typical Gear Ratios
North Carolina Coastal Fishing states, “Fishing reels offer differing gear ratios, ranging from slow retrieves (2.0.1 or 3.0.1) to high-speed retrieves (4.0.1 to 6.0.1).” Many avid fishing enthusiasts maintain a selection of reels with different ratios that provide options for deep water fishing, trolling and casting bait or lures.
Most manufacturers produce a line of reels with midrange gear ratios from 4.0.1 to 5.0.1, which is suitable for many types of fishing. The size of reels and line capacity varies with freshwater reels and saltwater reels. However, this does not affect the specific gear ratio that's built into a particular reel.
High Speed Reels
Certain types of fishing require line to be recovered at a high rate. A ratio of 6.0.1 is often preferred when casting lures for species, such as tuna and wahoo. High speed reels have a combination of speed and power that's needed to land game fish. With spools that have a circumference of approximately 8 inches when filled with line, these reels have a recovery rate of 4 feet, or 1.33 yards of line with each turn of the handle.
Two Speed Reels
Accounts of big game fishing often describe instances where a marlin or tuna made a quick turn and headed toward the boat. This situation calls for rapidly recovering slack line in order to keep tension on the hook. The losses of big game fish as a result of suddenly slacked line most likely prompted the advent of two speed reels. The fisherman can change to a 6.0.1 gear ratio for high speed retrieve, recover the slack line and change back to the more powerful 3.0.1 setting with a flip of the selector lever.