12 or 10 seems to be the "average" main kite size for Sydney kiters

When you say the average or most common, does that mean the best or what you would reccomend for Sydney?

You'll always need a bigger kite on the northside

I find that at the start of the season I'm using my biggest kites, mid season it's always 25 knots+ use a 7 m inflatable or a 3m foil and towards the end it's back onto my biggest likes again, biggest I mean 19 venom or 10.5 blade.

A good way to make the most of a 12m is get 10 extentions, every 3m of extentions give you and extra size to you 12m .

the 19 venom on 40m line can get me going in 5 knots easy.. and I can still hold it down to about 20 knots.

you can get by with a 12m on 40m line but you have to remove your finns the extra drag kills the kite in light winds

Also a kiteboarding newb here... is a 9m or 10m best for someone who is around 63kg? I've had some lessons and have done a little land-kiting, hopefully getting a kite for the water in the near future and heading out (Sydney).