How to Tie Backing to a Fly Reel

Why fly reels need backing

Backing is thin braided line — usually Dacron or gel-spun polyethylene — that gets wound onto the reel spool before the fly line. It does two jobs that have nothing to do with casting:

1. It gives you a reserve of line. A typical fly line is only 90-105 feet long. A big trout, and especially a steelhead, salmon, or saltwater fish, can easily strip out all of that fly line on a hard run. Backing is what’s left on the reel to keep the fish from simply taking all your line and breaking off.
2. It builds up the arbor. Winding a layer of backing underneath the fly line increases the effective diameter of the spool. That means each turn of the handle picks up more line, which matters when you’re racing to catch up with a fish swimming back toward you.

Even on a small stream chasing six-inch brookies, you still want backing on the reel — it’s not just insurance for big fish, it’s also what keeps the fly line from sitting too loosely wound around a bare arbor.

Choosing backing material and amount

Most fly anglers use one of two materials:

• Dacron backing — braided nylon, the traditional choice. It’s inexpensive, easy to tie knots in, and plenty strong for freshwater trout, bass, and pike.
• Gel-spun polyethylene (GSP) backing — thinner and stronger than Dacron at the same breaking strength, so you can fit more yards on a given reel. It’s common on reels with limited arbor space, or when anglers want maximum backing capacity for long saltwater runs.

How much you need depends on your target species and reel capacity:

• Most freshwater trout, bass, and panfish setups: 100-150 yards of 20 lb backing is standard.
• Saltwater, steelhead, and salmon setups: 200-250 yards is a common starting point, since these fish make longer, harder runs.

Check your reel manufacturer’s spec sheet first — most reels list a recommended backing capacity for a given line weight, and it’s easy to overfill a small-arbor reel.

What knot to use: the arbor knot

The standard knot for attaching backing to a reel is the arbor knot. It’s really two simple overhand knots working together: one knot cinches around the reel arbor itself, and a second knot (tied in the tag end) jams up against the first to keep it from slipping. It’s fast to tie, doesn’t require any special tools, and holds securely under the load backing typically sees.

Step-by-step: tying backing to the reel

1. Set your retrieve direction first. Decide whether the reel will be right-hand retrieve or left-hand retrieve based on which hand you cast with, and make sure the reel is mounted on the rod so the handle is on the correct side before you start winding anything on.
2. Pass the backing around the arbor. Loop the end of the backing around the center post (arbor) of the spool.
3. Tie an overhand knot around the standing line. Take the short tag end and tie a simple overhand knot around the long, standing part of the backing.
4. Tie a second overhand knot in the tag end. A few inches further down the tag end, tie another overhand knot — this one on its own, not around the standing line.
5. Cinch it down. Pull on the standing line so the first knot slides down and jams against the arbor, then pull again so the second knot jams up against the first. Trim the excess tag end.
6. Spool the backing on evenly, under tension. Reel the backing on while keeping light, constant tension on the line (running it through your fingers works fine). Keep an eye on the spool as you go to make sure the backing builds up evenly across its width rather than piling up on one side.
7. Stop at your target yardage, then attach the fly line to the end of the backing (typically with a nail knot or an Albright knot) and continue spooling until the fly line fills the rest of the reel.

Common mistakes to avoid

• Winding backing on loose. Slack backing can shift and bind under the fly line later, causing tangles or a jammed reel mid-fight with a fish. Keep tension on it the entire time you spool.
• Setting up the wrong retrieve direction. Figure out right-hand vs. left-hand retrieve before you tie anything on — unwinding and redoing a full spool of backing is a frustrating way to learn this lesson.
• Skimping on yardage for bigger water. It’s tempting to put on the minimum, but running out of backing on a hard-running fish means a guaranteed break-off. When in doubt, round up.
• Uneven winding. Letting backing pile up unevenly on one side of the spool can cause it to rub against the reel frame. Guide it across the spool with your fingers as it goes on.

FAQ

Can you use braided line for backing on a fly reel? Yes — standard fly line backing is braided line. Dacron and gel-spun polyethylene are both braided materials, and either is a correct, standard choice. What matters is matching the breaking strength and yardage to your target species and reel capacity, not whether the line is braided.

What is the 60/20/20 rule in fly fishing? That’s a leader-building guideline, not a backing concept — it’s a rough proportion (60% butt section, 20% taper, 20% tippet) some anglers use when hand-tying a knotted leader. It doesn’t apply to how much backing you put on a reel. For more on leader setups, see our guide to northern pike fly fishing leaders.