RIO Products Dacron Fly Line Backing High-Strength Braided Line 20lb/30lb Multiple Colors and Lengths Review (2026)

Who this backing is for

Fly line backing exists to do two jobs: fill out a reel spool so your fly line sits at a good diameter for casting, and give you extra line to fight a fish that strips off your entire fly line. RIO's Dacron backing suits almost any angler setting up a trout, bass or general freshwater fly reel, since 20lb test covers typical trout and bass work while 30lb test suits larger fish or reels with more spool capacity to fill. Anglers new to fly fishing who are spooling a reel for the first time will find this a straightforward, well-known choice rather than a specialty product, and anglers replacing worn or waterlogged old backing can swap it in without changing how their setup handles. Saltwater anglers chasing fish capable of very long runs may want to look at thinner gel spun backing instead, since it packs more yardage into the same spool space than Dacron.

What Dacron backing actually is

Dacron is a braided polyester material, and RIO's version is offered in 20lb and 30lb test strengths, in spool lengths of 100, 200 or 300 yards, and in colors including chartreuse, orange, white and dark blue so you can pick whichever is easiest for you to see against your fly line. Compared with gel spun or braided backing made from ultra-thin fibers, Dacron has a larger diameter for a given breaking strength, which means it takes up more room on the spool, but that same construction makes it noticeably easier to tie knots in. RIO specifically designs this backing to strike a balance between thinness and the ability to form a blind splice loop, a knot anglers use to connect backing to fly line without adding bulk. The line is made in the USA, a detail worth knowing if you prefer to buy backing built by the same company that makes the fly line and leaders it will pair with.

Spooling it up and using it day to day

Getting backing onto a reel is a one-time setup task: you attach the backing to the reel arbor, wind on enough length to bring your fly line up to the right diameter for the reel's spool, then attach the fly line itself with a blind splice loop or a nail knot. Because Dacron backing knots more easily than thinner gel spun options, this step goes faster and the resulting connection is less fiddly to tie correctly, which matters if you are rigging a reel for the first time. Once it is on the reel, backing needs very little day-to-day attention, though it is worth rinsing your reel and line with fresh water after saltwater or heavily silted trips, since grit worked into any braided line can accelerate wear over repeated casts and fights. Check the backing to fly line connection occasionally for fraying, particularly after landing a fish that pulled well into the backing.

How it compares with other backing options

In the site's fly line backing guide this RIO Dacron backing ranks first of seven, ahead of Cortland's Gel Spun backing at 300 yards and 30lb, which scores 8.8, and Scientific Anglers' 20lb Dacron backing, which scores 8.6. The Cortland gel spun option packs more length into less spool space since gel spun fiber is thinner per pound of strength than Dacron, which matters most to anglers targeting fish with very long, fast runs where reel capacity is tight. For the great majority of trout and general freshwater fly fishing, though, Dacron's easier knot-tying and lower cost per yard make it the more practical everyday choice, which is reflected in RIO's backing sitting at the top of the guide. Choosing between the lengths and test strengths mostly comes down to matching your reel's arbor size and the fish you expect to hook, rather than any real weakness in the line itself.

Verdict and who should choose differently

Pick this RIO Dacron backing if you want dependable, easy-to-knot backing for a trout, bass or general freshwater fly reel, and you are comfortable choosing the length and test strength that matches your reel's spool capacity. Its multiple color options also make it a sensible pick if you want backing that stays visible against your fly line for judging how deep a fish has run. Anglers targeting saltwater species known for long, fast runs, where every extra yard of capacity matters, should look at a gel spun backing instead, since it fits more length into the same spool space even though it can be trickier to knot. For typical freshwater fly fishing, this backing's combination of strength, easy knotting and made-in-USA construction explains its top ranking in the site's guide.

Frequently asked questions