I would not steal the other thread "Re: What is the perfect wind?" - so just took the last post from Saami for a new thread, as this topic is really interesting :
Saami wrote:
Peter / Supa, regarding the discussion about being able to ride Down-the-Line with large 15m+ kites - is it possible that you guys are thinking about different wind directions?
I, too, have never seen a normal-weight wavekiter ride down-the-line (with repeated, connected top and bottom turns) on a 15m kite or larger. However, I can imagine that it would be quite possible to do it with the right angle of side-offshore wind, such that you are basically on a close reach when speeding down the face of the wave after your top turn (i.e., heading slightly upwind), and on a broad reach after your bottom turn. That way, you should be able to keep the kite parked behind the waveline, and even if the kitelines momentarily go slack after your bottom turn, they should snap tight again after your next top turn.
But if we are talking light side-shore or, even worse, side-onshore or onshore wind... That would be tough to pull off using a really big kite for your average-weight rider.
Peter's point about the rider's weight is a good one. For a 120 kg rider, down-the-line riding with a 15m kite or bigger is not such a big deal, simply because he would be riding the 15m in much higher wind speeds (and given his weight and the higher wind speed, the 15m kite will be decently reactive). It's for the normal 75-80 kg rider that a 15m kite means really marginal wind - and in those conditions down-the-line riding becomes much more challenging.
Yes, I am talking side-maybe-slightly-on, or clean sideshore waveriding in light winds where you are really aggressive with the big kite (12m2), even more than with normal wavekites, in order to ride DTL
Of course it is only my opinion as I wrote - but really curious now if you are talking about the same conditions Supaez - as I have never seen anyone do this (not even anyone being ABLE to do this) in winds around 12 knots and hot
Btw - what linelengths do you use with this size for DTL riding ?
I havent even seen anyone doing it even with kites smaller than 19m2, say 15 or 17m2 if 75-80kg winds.
So I might dare and go a little further and say, it is the opinion of MANY and not only me

I do not say it does not happen - but would like to see HOW it is done ?
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Anyone got video where you see active sideshore DTL riding with a 17-19m2 in winds where this size is needed ?
Maybe you Supaez ? Would be easy when out so often in these winds - just a minute with a videocam from the beach so one can see the kite and rider.
Still amazed how this is done, as I am pretty experienced myself at riding waves DTL with ridiculous big kites in low winds (according to others) - but above 12 or 14m2 for 75-80kg do not work for me nor any of my fellow kiters, but 12-14 SLE is possible for some, yes, but on the limit of not being an option at all IMO.
Looking forward to see, and learn
I have tried borrowing friends big kites or big foils (a 19m2 silverarrow too), and it was possible to ride DTL pretty okay in some cases.
BUT - those days I could do the very same (just way faster) and still go upwind fine with my 12m2, so of course that does not count when sufficient wind, as the last you would want to do, is go out with a kite bigger than needed in waves
Meaning, if I can ride waves with a 10m2 kite on a given day, and I took a 17m2, it would be easy to ride waves with the 17 (but not much fun compared to the 10).
But if the wind was lower so it was only possible to ride and go slightly upwind with a 17 and not smaller kites, it would not work for DTL waveriding for me, simply because the windspeed is too low, as Saami also points out
Rider weight is an important factor, for me it is 77-78kg.
And no, I dont do downwinders either...

Peter