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Kite lines - a science of its own

Feb 14, 2012

Author: Flysurfer

Flysurfer Kites are technically very complex products. Over 1000 single parts must optimally function together on a Speed3, for instance. And whoever has adjusted the mixer of a Flysurfer kite, knows how small adjustments make a huge difference in the way a kite flies. It is not for nothing that our kites are tested up to three times before they reach the hands of their new owner. And that is exactly why we, as manufacturer, put a lot of thought into each and every part. At this point we would like to share some background information from our development on a very important part of each Flysurfer kite: the lines.

Whoever has first laid out their Flysurfer kite for the first time will probably have some respect for the many bridles which are attached to the kite. If you know at least a little about the Materials, you will notice quickly that the system is not too difficult, and in the end you have to do a lot less sorting or untangling than with a kite that has to be separately attached to the bar before every session.

For this reason, we will introduce every component from the chicken loop to the canopy.


The first line that you have in front of your nose when flying the kite: the depower line.

The depower line carries the entire load of the kitesurfer and if it breaks, serious consequences can be the result.  For this reason, Flysurfer kites have a very abrasion-resistant depower line, just to play it safe.
It still does not hurt to replace the depower line when it starts to disintegrate.

We put a lot of effort into making this component as reasonable priced as possible, since it gets the most wear and tear of all the components. Additionally, all of our kites are delivered with a replacement depower line.

The use of tubes as a cover around the depower line is currently not under consideration, since they break in low temperatures and then the bar can get hooked on the areas of breakage, making it impossible to depower.
Die Vorlaufleinen

For Flysurfer as All-Terrain-Kites, often put to use in the snow, this is naturally a no-go. Additionally, using tubes could lead to problems with our fully untwistable bar system. The next line that you often have contact with is the front line, a somewhat thicker and easily accessible line needed, for example, when relaunching.

However, as a kitesurfer, the flight lines are the most important, which truly provide an amazing function. They should provide the most optimal compromise of tensile strength, diameter and stiffness and long product life at the same time. As a general rule, woven Dyneema lines with a breaking strength of 250 – 300 daN (with almost the same load capacity in kilograms) are used. Our front lines, in new condition, can take somewhat more load – over 400 daN.

Gliederung der Waage eines Flysurfer-Kites

In the Mixer, the pulley construction above the flying lines, the steering commands and tractive forces are distributed to the bridle lines and thus to the kite. Most of our kites have four levels of bridle lines. The very back one is the brak (BR)  as well, also called the Z-level. The others are numbered from front to back with A, B and C. Some paragliders have an additional D-level, but this is not necessary on kites.

In the long run, it is our goal to use the very minimum of lines. To reduce drag and the danger of getting tangles, there are main lines for every level (A-Main, Z-Main, etc.), which divide once again towards the kite.


Eine pinke LCLeine weiße LCL
There are small line parts about one centimeter long at the connections, the so-called little connection lines or LCLs.

These serve to facilitate the replacement of defective bridle lines and at the same time as a predetermined breaking point at excessive load. For example, when a wave breaks on a kite and the kiter is still hooked-in, this small innovation has saved one or another cost-intensive repairs.

An amazing Material

Different constructions enable a line to fulfill its function. Basically, there are two major types of lines: covered and uncovered.

Unterschiedliche Leinentypen

While the uncovered lines consist of a hollow woven structure, the covered lines have a woven core with a cover over it. The advantage of an uncovered line is a smaller diameter and thus, less drag, as well as the smoother workmanship. In contrast, covered lines are especially constant in length and the cover protects the line core, which carries the load. Exactly because of that, our increasing tendency is to use covered lines for the bridle lines. It is not recommended, however, to use covered lines for the flying lines, due to one very simple reason: Since these lines are coarser, it could happen that the kite could no longer be controlled after  a double rotation.

Sparepartleine am Pully

For lines that go through pulleys, nothing else can be considered, since these lines are constantly bent and diverted and would shrink too quickly. The neon yellow spare part lines of the mixer (the lines which run over the pulleys) are a special development made exactly for this purpose: constant length over a long period of time and high abrasion resistance.

For the requirements that we place on our lines in our sport, two materials in particular have turned out to be particularly suitable: Polyester and Dyneema. Dyneema is a high-strength polyethylen fiber, produced in a special process (a so-called gel-spin process). Along with an unbelievably good tensile strength, Dyneema also offers a good abrasion resistance and resists dampness. Additionally, it is resistant to numerous chemicals. Not only is the production patented, the term is a brand name. Thus, most kite lines find their origin in a Dutch company.
Spektra is another high-strength Polyethylen, which is only seldom used in the kiting sector. Polyester can not compete with the unbelievable tensile strength of a Dyneema fiber. But it does offer another advantage: It is very abrasion- and UV resistant. For this reason, line covers are usually manufactured from polyester. How the fibres are manufactured depends upon the experience of the line manufacturers. And there is an enormous difference. Flysurfer has been working, with regard to flying lines, together with the German manufacturer Liros for many years now and has played a part in numerous new developments.

The basic manufacturing procedure is always identical. The fibers must first be spun into a yarn and this must be woven in turn. There are various weave patterns and finish processes, so a whole lot of variables that can be adjusted. At the end of the production, the lines are once again prestretched, heated and waxed at high temperature and close to the breaking load. This guarantees that the lines will not stretch over time. And also when many may believe otherwise: They really do not stretch.

Ends good, everything good?

How the lines end is usually a decision of the kiting company itself. The simplest variation is a knot. However, this can reduce the breaking load of a line by more than half, since you bend it around a very narrow radius and the fibers are thereby subjected to different load. For this reason, you will seldom find knotted lines on kites. It is more common to simply sew the lines, as we do with all of our covered lines. On many kites, the flying lines are provided with a cover on a short piece before sewing. This is advantageous where the connections are opened more often and tied. You will not find this variation on our kites, since the most elegant and most effective variation with regard to breaking load is the splice. A splice means pulling one line end through the line and sewn, so that a loop results. A very clean end is produced, which cannot get caught and holds extremely well. However, this option is only for uncovered lines, like our flying lines. Furthermore, splicing is handwork and therefore relatively complex and expensive.

Aging means shrinking – Or: the properties of a line over time
If you have ever compared the lines of an older kite, then you have most likely noticed that the frontlines have lengthened over time in comparison to the backlines. If you took the time to measure, you would notice that it is actually the back lines which have shortened, whereas the front lines have hardly changed at all. Confusing, at first, but enlightening if you take a closer look.

Längenunterschiede bei den Flugleinen

You have to have it in the back of your head that the lines are extremely prestretched and cured before delivery. Bending the lines (e.g. while winding) or abrasion (e.g. after rotations), the coating of a line fractures. In addition, sand or düst can get into the lines over time. Both have an effect: the line gets thicker and therefore, shorter. This is almost and sometimes entirely reversed by the frontlines, by the high load that must be carried while kiting. Still, while the back lines are subject to only a little load, they shorten remarkably, sometimes up to 20 centimeters. In order to balance this, there is a small black line, the depower leader line, above the adjuster, which can be simply adjusted in length. Under normal use, the lines should be readjusted after one year, earlier under frequent use.

Whether the lines are correct can be easily checked. Fix all the lines to a point, open the adjuster and tension the lines on the bar. Frontlines and backlines should now be tensioned to exactly the same degree. At a certain time, even readjusting will no longer help: Just like you, the life of every line will eventually come to an end.

Exactly how long this will take depends highly on the amount of use. For most kiters this means many years, yet it does not hurt to replace a part once you no longer trust it. First the depower line, then the spare part lines in the mixer, followed by the flying lines.

It is also important to replace paired lines (Mixer, flying lines, bridle lines), because as we noted before, aging causes shrinkage – and if you do not replace them it could lead in certain conditions to the kite flying inconsistently.

Here, summarized once again, what you should do so that your lines last as long as possible:

  • Rinse off with freshwater and allow to dry in the shade before storing over long periods of time
  • Do not bend or knot the lines
  • Avoid UV-exposure (do not let the kite lay around on the beach)
  • If the lines get caught on an obstacle (tree, rock), untangle them carefully if possible. Pulling with excessive force can result in permanent damage to the lines and can negatively influence the symmetry (lines are subsequently different lengths).

You should check your lines for damage every time you lay them out. Replacement is recommended if you notice any clear signs of wear and tear. Always replace symmetrically to avoid negatively influencing the kite geometry, since in the end it will only effect your fun if the kite flies badly.


All replacement lines can be found in our Online Shop


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