You watch a trophy submarine make a bow wave towards your fly… How confident are you that the welded wire trace loop will hold? I did some testing to find out and the results surprised me…

I have been making and using welded wire traces for my pike fly fishing (detailed here) almost exclusively over the last two seasons.  At the leader end, I use a loop-to-loop connection. At the fly end I have been trialling a variety of methods including lefty-kreh loop knots, round or oval split rings (work well but cumbersome) and most recently via snap connectors such as the Scientific Anglers stay-loc snap.  More on split rings and snaps in a future article, as some work, but many are not suitable for fly fishing.

Every time I made or fished a wire leader, I had two questions at the back of my mind.  1) How many twists are needed to give you full strength and 2) How strong are these welded loops vs a tied loop knot.

I ran a simple experiment to find out. Essentially I created a number of leaders, where I made the welded loops with either 1,2 or 3 twists and then pulled them to failure using a digital scale.  As a control I tied some loops with the lefty kreh loop knot.  The results are fascinating (to me).


  • Partridge 49 strand, 20lb wire tippet
  • Partridge 49 strand, 40lb wire tipper
  • Savage Gear Digital Scale 30kg

The 49 strand wire is superbly supple and what I use.  Other wires may have different results.

Preparing the Welded Loops

With the 20lb wire, I prepared a series of wire leader sections, in triplicate, with a welded loop at each end. These were made with 1, 2 or 3 twists of the wire, before melting the nylon sheath together with a lighter.

With the 40lb wire, I only prepared a single set of 3 with 2x twists.

Testing the failure Point:

I set up the digital scale and created a wooden block with a hook. This allowed for a rudimentary assessment of breaking strain and failure mode. I filmed each test, which allowed me to record the final strain.

Stress Test Rig

So, what were the results?

Summary of the results for the 20lb/9kg wire. Results shown in kg as the average of 3 repeats +- standard deviation.  A Lefty Kreh loop is not a great option with this thin supple wire leader.  Welding of loops is surprisingly effective where only 3 twists already retains 100% breaking strain.

The Lefty Kreh loop knot is pretty poor on 9kg/20lb wire.  Probably due to my poor knot tying skills, but one of the 3 knots failed at 2.5kg, with the other two around the 6kg mark – which is still only retaining 60% of breaking strain.

The single twist weld was as expected, poor, but higher than I would have guessed, retaining almost 50% breaking strain before the loops opened.  The 2x twist weld loop was inconsistent with some opening and others snapping, but already superior to the Lefty Kreh loop knot.  With three twists, the results are exceptional, retaining 99% breaking strain, and not a single loop failing.

For the 40lb leader, I only tested the 2x twisted welded loop.  While the loops opened in each of the three tests, they did so at over 100% of rated breaking strain – more than 18kg on average! I suspect that the wire is stronger than the rates 40lb. Either way, the test was pretty violent and I did not feel the need to repeat with an increasing number of twists.

In Summary, you can trust a welded loop! They retain 100% breaking strain and you just need to make them with 4 or 5 twists. 

Three twists probably does it, but to account for wear and tear on the water, hotter or colder conditions, an explosive jarring take, the extra couple of twists should put the mind at ease, while still remaining slim and tidy.

The next weakest link is probably the wire to fly connection. More on this coming soon as I explore the world of snaps and split rings.

Full results:

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