How to Attach Backing to Fly Line: Step-by-Step

To attach backing to fly line, first tie the backing to the reel arbor with an arbor knot and wind it on under light tension. Then join the backing to the fly line, either loop to loop if your fly line has a welded loop, or with an Albright or nail knot if it does not. The connection should be smooth enough to slide through the rod guides when a fish runs.

This guide walks through each step, including how to set the retrieve direction and how much backing to use. If you are setting up a new outfit, see our fly reels and beginner fly fishing kits guides, and the fly line section.

What You Need

• Fly reel and spool
• Dacron or gel-spun backing
• Fly line
• Clippers or scissors
• Optional: a nail knot tool or a small tube, and flexible cement for smoothing knots

Step 1: Set the Retrieve Direction

Decide which hand you will reel with and set the reel for left- or right-hand retrieve before you add any line. Most reels convert with a simple switch or by flipping a clutch. Check your reel’s instructions. Winding line on in the wrong direction means starting over.

Step 2: Tie the Backing to the Reel (Arbor Knot)

1. Pass the backing around the reel arbor (the center of the spool) and back out.
2. Tie an overhand knot with the tag end around the main backing line.
3. Tie a second overhand knot in the tag end only, a few inches from the first. This acts as a stopper.
4. Pull the main line so the first knot slides down and snugs against the arbor, then the stopper knot jams against it. Trim.

Step 3: Wind on the Backing

1. Hold the backing spool on a pencil or have a helper hold it so it turns freely.
2. Reel the backing on under light, even tension, pinching the line between your fingers.
3. Guide the backing back and forth so it lays evenly across the spool.
4. Stop when you reach the amount your reel maker recommends for your line weight. Reel makers usually list it, such as WF7 plus 180 yards of backing on a 7/8 reel.

Tip: If you are unsure how much backing fits, wind the fly line on first, then fill the rest of the spool with backing, then strip it all off and put it back on in the correct order.

Step 4: Connect Backing to Fly Line

Option A: Loop to loop (easiest)

Many modern fly lines have a welded loop on the back end. Tie a loop in the backing, then join the two loops.

1. Tie a large loop in the end of the backing. A surgeon’s loop works; many anglers use a Bimini twist or spider hitch for a longer, stronger loop. Make the loop big enough to pass the fly line reel or coil through.
2. Pass the backing loop through the fly line loop.
3. Pass the entire fly line (still coiled) through the backing loop.
4. Pull tight so the loops interlock like a square knot, not girth-hitched on each other.

Loop to loop lets you change fly lines without cutting.

Option B: Albright knot

Use this when the fly line has no loop.

1. Fold the end of the fly line back to form a loop.
2. Pass the backing through the loop and wrap it tightly back over all three strands about 10 times toward the loop’s end.
3. Pass the backing back out through the loop the same way it entered.
4. Pull the backing tight, then pull the fly line and backing apart. Trim.

Option C: Nail knot

A slim, smooth knot that passes easily through guides.

1. Lay a small tube or nail knot tool alongside the end of the fly line.
2. Lay the backing alongside them, pointing the other way, and wrap it back over the tube and fly line six to eight times.
3. Pass the backing tag back through the tube, then slide the tube out.
4. Tighten slowly, pulling both ends of the backing, and trim. A thin coat of flexible cement helps it glide through guides.

Step 5: Wind on the Fly Line

1. Check the fly line box. Many lines are labeled “this end to reel” or “backing end.”
2. Reel the fly line on under light tension so it lays evenly.
3. Leave the front loop or tip ready for your leader.

Common Mistakes

• Wrong retrieve direction. Set left or right hand first.
• Loose backing. Loose wraps let line dig in under pressure.
• Overfilling the spool. The line rubs the reel frame. Leave a little space below the rim.
• Bulky connections. A large knot can catch in the guides when a fish runs.
• Loops girth-hitched. Loops should interlock squarely; a girth hitch can cut through.

Tips

• Use a contrasting backing color so you can see where the fly line ends.
• Mark the line weight on the backing near the reel for quick identification.
• Check the connection each season for wear.
• Many fly shops add backing and line for free or a small fee when you buy a reel or line.

Related Guides

• Best Fly Reels
• Best Beginner Fly Fishing Kits
• Best Fishing Knots
• Best 5 Weight Fly Rods

FAQ

What knot connects backing to fly line?

Loop to loop is easiest if the fly line has a welded loop. Otherwise, use an Albright or nail knot.

How much backing do I need?

Follow your reel’s recommended capacity for your line weight. Trout anglers often need less; steelhead, salmon, and saltwater anglers fill the spool.

Do I need backing for trout?

Yes, a little. Backing fills the arbor so line comes in faster and gives you insurance if a big fish runs.

What backing strength should I use?

Common choices are 20 lb Dacron for trout and many freshwater reels and 30 lb for larger saltwater reels. Follow your reel maker’s guidance.

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