Tag: LEI

Leading Edge Inflatable Kite Setup in 7 Simple Steps

Posted on by Jen Bell-Taylor

A Leading Edge Inflatable Kite is more commonly known as an LEI kite and is the most common design of kite in the modern kitesurfing world. With these kites you have to inflate the leading edge – thanks to the innovative design of this kite, we can relaunch our kites, continuing our sessions crash after crash, massively aiding the curve of improvement of kiters and the industry entirely.

Where to set up your Leading Edge Inflatable Kite

leading-edge-inflatable-kite-setup

Before you start setting up the Leading Edge Inflatable (LEI) kite, do a site assessment using the mnemonic SHOE to guide you. Are you confident that you’re setting up the correct size kite? You can use this kite size calculation (link) to choose the right kite for your weight and wind speed.
You should set up your LEI kite in an area away from hazards with plenty of space to run your lines.

Setting up your LEI kite

Position yourself to inflate the kite by standing with your back to the wind and the kite downwind of you. Hold the kite by the inflatable leading edge and open up the kite fully before inflating. Connect your harness leash to the kite so that the kite can’t blow away from you with the wind.

Don’t forget to close the deflate valve. Your deflate valve needs to be closed tight so air can’t escape; check for sand before closing. You’ll either have separate inflate and deflate valves or have a single valve that features both inflate and deflate in its design.

Types of LEI kite valves

A standard 11mm deflate valve will require you to push hard to close it. When it’s done properly, you’ll feel it click into place. Put your hand on the other side of the leading edge, underneath the valve, so that you can support it and push hard.

A Boston valve is a 2 layered valve with inflate and deflate separated by a non-return flap. Unscrew the top cap to expose the inflate before you screw in deflate cap.

Some kites use a twist lock mechanism. Duotone and F-one both require their own non-standard pump nozzle to work with their own inflate/deflate systems. Always check that the valve is in the closed position before inflating so the kite doesn’t deflate immediately when you remove the pump nozzle.
Link to duotone pump system
Link to F-One pump system

Pumping up your LEI kite

Your kite will either have multiple points of inflation, or a Single Pump System (SPS). If your kite is multi-pump, start by inflating each strut before inflating the leading edge

Inflate your Leading Edge Inflatable kite with your back to the wind. Keep both feet on the pump at all times, keep your back straight and use your knees so you don’t strain your back while pumping the kite. The kite is inflated properly when it is firm but will bend with mild resistance. Do not inflate over 6PSI while learning. You can then disconnect the pump and close the inflate cap, again making sure it is free from sand.

Weighing down your LEI kite

Park the kite by turning it over then weigh it down so it can’t move with the wind. To turn the kite over, keep your back to the wind then walk the kite over by pressing one wingtip into the sand and using that as the pivot point. Your kite will face directly upwind and the wind passing evenly over either side of the centre strut.
To keep the kite secure, throw a few kilograms of sand onto the leading edge and down towards the trailing edge. Never put stones on your Leading Edge Inflatable kite.

Before you move on to your bar, check each bridle is accessible and untangled, and ready for your lines. Your bridles should come towards you without any twists and pulleys able to move freely. Both bridles will be the same length.

Preparing and connecting your kite bar

Unwind your lines walking downwind from the kite. Lay out the bar on the sand so that it is upside down (red on right for setup) and the depower rope runs straight through the bar.

Separating your lines

Separate your lines by keeping the 2 front (inside) lines between your knees and steering lines outside your knees. Walk up the line length removing any twists and making sure each line runs cleanly to each bridle point without passing around another line. If your lines are especially twisted, run the steering lines to the LEI kite first, then run the front lines separately.

Connecting your lines to your LEI kite

Connect your lines to each bridle connection point. Form the larks head loop and place it over the pigtail. The larks head is made by passing the lines loop end over the section of line directly beneath the loop and pulling the line section through. Once you pass the pigtail through the larks head loop the larks head can tighten against it. Pull tight and double check that the larks head loop is snug against the pigtail knot.

Your kite may have multiple connection options. Have a read of this guide to tuning your LEI kitesurfing kite (link) to choose the best setup for the conditions you are riding in.

Repeat this for each connection point. Double check that each connection is pulled tight and that the lines run straight to the bar and are not twisted over each other. DO NOT try to launch the kite if you are not confident that the Leading Edge Inflatable kite is set up properly.

Do your Preflight Checks


There are many more accidents happening around rushed setup and mistakes made during launching than there are with riders out on the water. We can’t emphasise enough how important it is to double check your actions as you set up and launch your Leading Edge Inflatable kite. Get into the habit of doing a series of pre-flight checks before you launch your kite (link).

  • Is every larks head connected properly? Check every connection is secure
  • Is there symmetry in your setup? Every connection should be the same as on the opposite side of the kite. Match up how you connect the steering lines on each side so that your lines are the same length and affect the kite evenly.
  • Are you definitely set up in the right place? Do you need to move away from hazards, and 3rd parties, closer to the water? Don’t launch directly upwind of objects or people. Move into an open space at least 50m away from hazards.
  • Are your safety releases working? Open your quick release and leash release then rebuild at the start of every session so that you know it is working. Check that your safety line pulls through cleanly.

How do Kitesurf Kites Fly ? A simple 4 piece puzzle

Posted on by Jen Bell-Taylor

Learning how a kitesurf kite works can improve your kiting abilities. Understand how your kitesurf kite works and what it needs and you could find yourself reading the environment around you, making for the best sessions of your life. Often a good kiter is a knowledgable kiter!

tony-flying-his-kitesurf-kite

How your bar controls your kitesurf kite.

Most modern Leading Edge Inflatable (LEI) kitesurf kites use a four-line bar with two front lines and two steering lines which connect to your kite’s bridles.

The two front lines of your bar connect to the leading edge attachment points and support the force of the kite, but do not control direction. The steering lines connect to the steering bridle attachment points and affect both direction of the kite and the kite’s angle of attack to the wind.

Your kite may have multiple connection options to adjust it’s performance. Take a look at this guide to tuning your LEI kite (link) to understand how you can use these settings.

As you connect your bars chicken loop to your harness, the force of the kite is not felt in your arms but in your core. You are able to control the angle of the kite to the wind by sheeting the bar in or out along the depower throw.

Forces acting on the kite

forces-acting-on-a-kitesurf-kite

The forces occurring as air passes over and under the kite effect how it flies. Like the wing of an aeroplane, our kite also deals with lift, drag, thrust, and gravity – it also has line tension as an additional force. We’ll quickly introduce these terms before explaining what the effects they have. To keep a kite flying steady the four forces must be in balance.

Lift is the upward force that pushes a kite into the air. Lift is generated by differences in air pressure, which is created by airflow passing above and below the body of the kite. Kites are designed so that air particles moving over the top of the wing, flow faster than the air moving over the bottom. Gravity acts as a downward force on the kite, relative to the weight of the kite. The force of the weight pulls the kite toward the ground.

Thrust is the forward force that propels a kite in the direction of motion. A kite relies on the tension from the lines and moving air created by the wind to generate thrust. Thrust is the reason why the kite will always fly towards the edge of the wind window and won’t stay in the power zone; the kite must fly towards the most upwind point of the wind window.

Drag is the backward force that acts opposite to the direction of motion. Drag is caused by the difference in air pressure between the front and back of the kite and the friction of the air moving over the surface of the kite.

Changing the angle of attack with the bar?

Angle of attack

As the wind reaches the kite, airflow splits at the leading edge of the kite passing over and under it’s surfaces, moving towards the trailing edge, and continuing downwind.

The flow of air going over and beneath the kite reach the trailing edge at the same time. Due to the angle of the kite, the airflow going over the top of the kite must accelerate to reach the trailing edge at the same moment as the airflow passing beneath.

It is this acceleration of airflow over the top of the kite that forms low pressure above the kite and creates lift. The more lift generated, the more it pulls you.

If flying a fixed bridle trainer kite, like the one you use in session one, it’s angle to the wind can only be changed by steering the kite into each zone in the wind window (link). As the kite is flown into the power zone, and the angle of attack is increased, you get the most pull (lift). This is because air is accelerating faster here to reach the trailing edge at the same time as the airflow passing the underside of the kite. You’ll also notice that the kite flies faster through the power zone due to increased thrust.

Sheeting in and sheeting out

If we are flying a depowerable kite, such as the Leading Edge Inflatable (LEI) kite used on the water part of your lessons, the bar can be “sheeted in” and “sheeted out”, pulling the bar closer to us or pushing further away from us along the depower throw. This movement of sheeting on the bar changes the kites angle of attack, giving you additional control over how much lift the kite generates.

Pushing the bar out: (Sheeting out) reduces rear line tension and reduces the kite’s angle of attack so the kite generates less lift. Which in turn pulls the wing tips and the trailing edge of the kite closer to the wind. The result is a tighter turn radius when steering and normally more power, though it is possible to negatively affect the kite by pulling in the bar too much.

Pulling the bar in: (Sheeting in) increases rear line tension and the angle of attack which generates more lift as airflow accelerates over the top of the kite. In this position, the kite generates less power but also has less line tension for controlling direction while steering. With the bar out, the turn radius of the kite will be large and the kite slower to respond to counter steering.

It’s important to remember that this is an additional factor to the amount of lift created by the position of the kite in the wind window. If you steer the kite through the power zone, the kite will still pull you hard, even with the bar sheeted out.

It is possible to “over-sheet” and pull the bar in too far, increasing the angle of attack beyond the kites stable flying range causing unbalanced forces on the kite. When we pull the bar in too far, the airflow over the top of the kite becomes turbulent and can no longer accelerate to the trailing edge to create lift and thrust. This results in an imbalance of pressure above the kite and increased drag. The kite will then “backstall” and fall backwards, instead of flying forwards.

You will be able to recognise when your kite is backstalling as it will feel sluggish, lose power and then fall backwards through its trailing edge. Pushing the bar out will correct this by reducing drag and allowing the kite to fly forwards again.

Our ability to recognise signs of backstalling will enable us to correct our input at the bar and put the kite into a more efficient flying position quickly. A great way to learn this skill is to practice light wind kite flying (link) as you will learn to be more aware of bar position while flying the kite.

Want to know more about the histroy of kitesurf kites? Have a look at this short film about the history of kitesurfing here

NEXT UP: How to launch and land a kitesurf kite