Diagram

Loop-to-Loop Connection

Handshake loop · Loop-to-loop join

Joining two finished loops, such as a fly-line loop and a leader loop, so the leader can be changed without cutting either line.

Line-to-line · Beginner · Fly line / Monofilament / Fluorocarbon / Braid · 4 steps

Applications How to tie it

Finished structure

Drawn from a rope model of this knot: which strand passes over which comes from where the rope actually lies.

Move 1 of 1Run each loop between finger and thumb and look closely where it is formedYou should now see: Both loops feel smooth all the way round, and the point where each loop is formed is tight and undamaged.
Step 01
Run each loop slowly between finger and thumb, and look closely at the point where the loop is formed on each line.
You should now see
Both loops feel smooth along their length, and the point where each loop is formed is tight and undamaged.
If it goes wrong
Joining to a loop with cracked coating or a frayed core. The damage shows as a rough spot, a kink, or a pale patch where the loop bends.
Fix: Cut off the damaged loop and make a new one before connecting. If the leader loop is the damaged one, tie a fresh loop in the leader.
Why: The finished connection is only as strong as the weaker of the two loops, and the connection loads each loop right where it bends.
Move 1 of 1Push the main-line loop through the leader loopYou should now see: The end of the fly-line loop sticks out through the leader loop and stays open on the far side.
Step 02
Push the loop on the main line or fly line through the loop on the leader.
You should now see
The end of the main-line loop sticks out through the leader loop and stays open on the far side.
If it goes wrong
Doing it the other way round and pushing the leader loop through the main-line loop. Finished that way, the leader loop ends up choking the main-line loop in a girth hitch.
Fix: Pull the leader loop back out and push the main-line loop through the leader loop instead.
Why: The main-line loop goes through first because the leader is the only part with a free end, and that end has to pass through the main-line loop next.
Move 1 of 2Feed the far end of the leader, tippet first, through the main-line loop
Move 2 of 2Draw the whole leader through the main-line loopYou should now see: The two loops hang linked but still loose, each loop passing around both strands of the other.
Step 03
Feed the far end of the leader, tippet first, through the main-line loop and draw the whole leader through.
You should now see
The two loops hang linked but still loose, each loop passing around both strands of the other.
If it goes wrong
Passing the leader through its own loop instead of the main-line loop. That ties the leader loop around the main line in a girth hitch, which looks tidy until it is pulled tight.
Fix: Pull the leader back out and feed it through the main-line loop, the one sticking through the leader loop.
Why: With each loop around both strands of the other, the two share the pull evenly. A leader passed through its own loop wraps one loop around a single bend of the other.
Move 1 of 1Pull the main line and the leader slowly apart until the two loops slide togetherYou should now see: Two interlocked U-shapes of similar size lie flat against each other, like a square knot; neither loop chokes the other.
Step 04
Pull the main line and the leader slowly away from each other until the two loops slide together.
You should now see
Two interlocked U-shapes of similar size lying flat against each other, looking like a square knot.
If it goes wrong
One loop cinching tight around the other while the other stays straight and open. That is a girth hitch, and it can cut into the loop it grips.
Fix: Push the loops apart, pull the leader back out, and repeat from step 2 with the main-line loop through the leader loop.
Why: A girth hitch puts the whole pull on one bend of the gripped loop. Undo it and connect again rather than fishing it.

Loop-to-Loop Connection — finished-state checks, on the shared reference layout — Hook the Horizon reference plate

Failure modes

When this family fails, it fails as these. The recovered end still outranks the name.

Loop-to-Loop Connection — what fails and what to do — Hook the Horizon reference plate

Loop-to-loop family

A loop that either stands as a dropper or handshake onto another loop.

!Dropper loop collapsed into an overhand
!Handshake twisted so one loop saws the other
!Loop sized after it was already loaded

Fails when

!The loops finish as a girth hitch, putting the pull on one bend so it can cut the gripped loop
!Either loop has cracked coating or a frayed core where it bends
!The knot or join that forms either loop is loose or damaged

Geometry

Assembled as a girth hitch
One loop cinches and cuts the other
Matching U-shapes only — a girth is a failed handshake · step 02
Oversized leader loop, or only the tippet through
Unfinished handshake; coating crushes
Both loops must pass fully and sit as a handshake · step 03
Factory loop already damaged
Crushed coating is a cut-off, not a retie of the handshake
Replace the loop; do not ‘fix’ a girth by pulling harder · step 01

If you saw this

One loop cinches and cuts the other
Check
- ?Matching U-shapes
- ?Neither loop collapsed
Then
- →Undo and reassemble as a handshake
- →Replace a damaged factory loop
Connection formed as a girth hitch instead of square interlock.
Check
- ?Look for: Connection formed as a girth hitch instead of square interlock.
Then
- →Retie as a true loop-to-loop interlock.
Loops enter twisted relative to each other.
Check
- ?Look for: Loops enter twisted relative to each other.
Then
- →Open, re-seat squarely, or reconnect.
One loop is far smaller and cuts the other.
Check
- ?Look for: One loop is far smaller and cuts the other.
Then
- →Match practical loop sizes.
Loop legs abrade at the contact point.
Check
- ?Look for: Loop legs abrade at the contact point.
Then
- →Inspect mid-session; retie nicked loops.
Finished check failed — one loop collapses into an accidental girth-hitch orientation
Check
- ?two finished loops interlock squarely
- ?load is shared across the intended loop legs
- ?connection can be separated without visible twist damage
Then
- →Retie. localized wear, distortion, or premature loop failure.
Assembled as a girth hitch
Check
- ?One loop cinches and cuts the other
- ?Inspect step 02
Then
- →Retie. Do not dress a defective structure and call it seated.
Oversized leader loop, or only the tippet through
Check
- ?Unfinished handshake; coating crushes
- ?Inspect step 03
Then
- →Retie. Do not dress a defective structure and call it seated.
Factory loop already damaged
Check
- ?Crushed coating is a cut-off, not a retie of the handshake
- ?Inspect step 01
Then
- →Retie. Do not dress a defective structure and call it seated.

Same family

Same failure class, different geometry. Open the plates — Diagnose still starts from the symptom.

This failed — start Diagnose

Why this knot

What it earns its place with, what it costs, and what to reach for instead.

Best for

Loop-to-loop

Not ideal for

Damaged factory loops
When lowest profile matters (Nail / Needle)
Girth-hitched assembly

Common mistakes

Leader loop pushed through the main-line loop instead of the other way round
Leader passed through its own loop instead of through the main-line loop
Joining to a loop with cracked coating or a frayed core

Alternatives

Perfection LoopBeginner
A small fixed loop in the end of a leader, tippet or fly line that lies in line with the standing line
Surgeon’s LoopBeginner
A fixed loop tied quickly in the end of a line, for a loop-to-loop connection or to let a lure or fly move freely on the loop
Nail KnotIntermediate
Joining a leader to the end of a fly line with a smooth, compact coil of wraps that passes through the rod guides

Loop-to-Loop Connection

Why this knot

Related knots