A baitcaster's gear ratio is not its retrieve speed. The ratio only tells you how many times the spool turns for each turn of the handle. The number that actually sets how fast line comes back is inches per turn, printed on the box as "line per handle turn," and it changes with the spool. Two reels stamped with almost the same ratio can pull in different lengths of line on every crank. If you buy by the ratio alone, you can end up with a slower reel than the one you thought you were upgrading to.
The definition is mechanical and simple. Wired2Fish, in its gear-ratio guide, puts it as: "The gear ratio of a reel is measured by how many times the spool turns for each single turn of the handle." Its worked example is a 6.4:1 reel, where "every time you turn the handle, the spool inside turns exactly 6.4 times."
That is all the number is. It is a relationship between two gears, not a distance. A 7.1:1 reel spins its spool 7.1 times per handle turn; a 5.1:1 reel spins it 5.1 times. Higher ratio, more spool revolutions, and, all else equal, a faster retrieve.
"All else equal" is the catch, and it almost never is. Wired2Fish names the second spec that matters: "It also helps to know the IPT of a reel or Inches Per Turn. This is a measure of how much line is retrieved into the reel with a single handle turn." And then the sentence that decides the whole subject: "Because spool size, depth and width can impact IPT, just because a reel is 7.3:1 or 8:1 doesn't necessarily mean it reels in more line per turn than a 7.1:1 reel -- it also depends on the spool and line size."
The spool turns a fixed number of times, but how much line each of those turns gathers depends on how much line is sitting out at the rim. A bigger spool, or a fuller one, pulls more line per turn at the same ratio. So the ratio fixes the gearing and leaves the actual speed floating on the spool underneath it.
You do not have to take this on faith. Manufacturers publish both numbers side by side, and on two Shimano reels the pair makes the point without any interpretation.
| Reel | Gear ratio | Line per handle turn |
|---|---|---|
| Curado DC 200 | 7.4:1 | 81 cm (31.9 in) |
| Curado DC 200 | 8.5:1 | 93 cm (36.6 in) |
| SLX DC 150 | 6.3:1 | 67 cm (26.4 in) |
| SLX DC 150 | 7.2:1 | 77 cm (30.3 in) |
| SLX DC 150 | 8.2:1 | 88 cm (34.6 in) |
Read the middle rows. The Curado DC 200 at 7.4:1 gathers 81 cm of line per handle turn. The SLX DC 150 at 7.2:1 gathers 77 cm. The ratios differ by two tenths; the line per turn differs by four centimetres, because the Curado 200 runs the larger spool. Now read across the two reels the other way: the SLX DC 150 at 8.2:1 picks up 88 cm per turn, more than the Curado DC 200 at 7.4:1 (81 cm). If you had compared only the numbers on the front of the box, you would have called the Curado the faster reel. The spec sheet says otherwise. Both figures come from the same published spec sheets covered in the Curado DC 200 vs SLX DC 150 comparison.
Once you stop treating the ratio as a speed and start treating it as a gearing choice, picking one gets easier. Wired2Fish splits the field into three bands, and the split is about torque versus speed, not about which is "better."
The highest torque of the three. Wired2Fish calls a lower ratio "ideal for big baits that pull a lot, such as deep crankbaits," and adds that these reels "are also great for slow rolling big, heavy baits such as spinnerbaits and swimbaits." You are trading handle speed for the ability to move a bait that fights the water.
The all-around band. It suits squarebill and medium-depth crankbaits, shallow spinnerbaits, and shallow castable umbrella rigs. The narrow spread inside this band still matters: the same writer runs a 6.4:1 for baits that trigger a reaction strike and drops to a 6.1:1 when cranking in the 8 to 14 foot range, where the small speed loss keeps the bait in the strike zone longer.
For anything you work mainly with the rod and need to pick up slack on quickly: jigs and big worms, shaky heads, Texas and Carolina rigs, topwaters, jerkbaits, and lipless crankbaits. Wired2Fish puts the reason plainly: "If you're fishing any bass fishing lure that you primarily work with your rod, a high gear ratio reel is the way to go. You're often pulling the bait with your rod tip, but you need to have the ability to quickly take up your slack when you get a bite." The same speed helps pull a fish away from cover before it frays the line.
The habit that costs money is reading the ratio as a ranking. A higher number is not a better reel, and it is not always the faster one. Three specific ways this bites:
Three things people expect the ratio to control, that it does not.