danw said...
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The wind speed was 15-20knots and gusting 30+ knots and I was on a 9 (78kg).
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This is what happens: 1 edging 2 gust hits.. try to get edge back but I keep gaining speed. Eventually going uncomfortably fast , drop my bum to break. Try again.
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Ok, this gives us a bit more info to work with.
What you are describing is a typical winter squall that most of us have to learn to deal with when it occurs on whatever size kite we happen to ride at the time.
Changing to a smaller kite is pointless, as these squalls only last for a few minutes and once it passes you'll be stuck with a small kite in 15-20 knots for the rest of the session which is not fun.

Besides,
what if the next squall you encounter is 40+, would an 8m save you? What about 50+? How small would you go? The short answer is, match your kite size (conservatively) to the prevailing conditions (which you did) and learn how to handle the squalls when they arrive.

The easy way to deal with them is to:
1) bar out
2)
(SLOWLY!) move your kite up - close to 12 o'clock and
3) edge hard upwind to keep the speed low
From your description it appears you were already pushing the bar out and trying to edge, but you were missing step 2. By moving the kite close to 12 o'clock you will be removing most of the pulling power.
And you MUST DO IT SLOWLY or you will be lifted off 
- the last thing you need in a squall. Don't worry if this takes a few seconds - you WILL eventually slow down and regain your edge - but don't rush!
And what if the squall is way too strong, or if you mess up? Simple answer - hit the QR and make sure you do it quickly, hesitation in this sport can be costly.