The below instruction/discussion assumes equal line length – all four of them.
The short (?) version or the getting started list:
Put your thumbs on top of the handles and grab them. Hold the handles in front of you and bend you elbows to roughly a square angle and slightly rotate your wrists to point a bit upwards. Trim your kite/line/handle setup so that you just can maintain a leading edge up hover (similar to a stalled dual line kite). Most commonly do this trimming by varying which knot that you attach the top lines larkheads to. If you are new to quads, from this reference position move the LE/top line closer to you/the handle by choosing a knot say perhaps 4cm closer to you to (in this hover case) increase the forward (up) drive.
Disregarding the handle shape (a much curved handle would make the lower leaders shorter than a less curved handle) and how you grip the handle (what angle you keep the handle), when piloting my Hadziki wing 1.5 REVs (a std normally shaped REV manufactured by Revolution) all lines and (handle side) larkheads are about the same distance from the from the kite.
A good starting length is 4 x 25m. Not shorter than 15m for the first flights. To get stiff enough lines and slippery enough to make it possible to control the kite with lines that are twisted after turning, you should use Spectra/Dyneema (Ultra-high-molecular-weight polyethylene (UHMWPE)). Use a 40”kg” line strength (equals 39daN or 88”lb”) for most winds. In light wind you can use a 25kg line, though it is somewhat more prone to get caught on stuff on the ground.
Handle trimming discussion:
Returning to the handle leader(/cord) length I could say what I use for various conditions, but that really depends of the bridle of the kite in the general case. Say that the attachment point knot on the bridle on a certain type of kite of quad would be far from the sail surface, then naturally the whole top lines would need to be closer towards the handle. This could be realized with a shorter leader adjustment.
You can’t just assume that the trimming that works for one kite (and conditions) just fits for another kite and you can maintain the same trimming. I extend the top leaders (by adding a short pigtail in series) on my REV-handles to fly my (B-series) REVs in mid wind range and hard wind. Only in lighter winds the top leaders of my REV-handles are sufficient using the outermost or second outermost knot. It is the brake-heavy feeling of a flying sail with no trailing edge flutter that I’m after. Higher wind requires more brake, otherwise the kite tends to constantly move forward if you don’t constantly apply brake yourself. Trailing edge flutter is a signal to add more brake. A kite that won't take off is a signal to fly less brake heavy.
So regardless if you bought your handles or DIYed them, which knots on the leaders should you use? What should you look for when trimming the whole setup? I aim for the following: when pointing the top sides of the handles somewhat towards you, you should just be able to maintain a (standard leading edge upwards) hover. Do this test in the centre of the wind window a couple of metres above the ground. With a brake-heavy setting like this, forward drive of the kite is mainly performed by pulling on all four lines. This pull on the kite will actually deform the LE and sail in such a way that the kite will be “kicked” forward (resulting in a good control of the forward motion).
Now I don’t recommend this setting to the *fresh* beginner (though you early in you QLK career should strive to understand and use this sail-deforming action). Instead when you have found this kind of a “neutral” trim, you should move the larkheads one or two knots (possibly three) on the top leader towards the handle.
So now to the question what leader length should you use? If I would make a pair of *curved* 13inch-like handles myself I’d make the top leaders about 24cm long and the bottom leaders perhaps 6cm. However if the handle would have been just a straight bar (for ease of manufacturing perhaps) the bottom leaders instead would need to be about as long as the top leaders (estimated – not actually tried). I’d use about 2cm knot distance on the top leaders. The bottom leaders should have the knots closer, since the function is to, if necessary, make small adjustments to trim the setup so that the kite doesn’t have any left/right (non political
) tendencies. When holding the handles when piloting my REVs, my Spiderkites Smithi Pro or my Anders Matson A-Quad Hard Wind Vent, I hold the top of the rubber grip while placing my thumbs on the top of the handles. However for the Smithi Pro and the A-Quad I first need to make them more brake heavy by using a bottom (trailing) side bridle attachment point that is closer to the sail. After this, the trimming using my REV handles will function as normal.