Here's a question (ignoring that I already have the 10m kite), as I understand it, what size kite you use has a lot to do with how heavy/strong you are. My friend spends his time in the winter on his 10m kite, but he only weighs ~150lbs while I'm 205lbs (so ~135% his weight). Would this mean that in conditions when he's on his 10m, I would be equally comfortable on a kite around 13.5m (in the range of 12m-14m)?

I'd really like to spend my time on the ice at the same time as my friend (ie. we'd get going at the same time). Would a 12m-14m kite be appropriate for this?

Sorry about the really basic questions, I never really thought about kite size when I just borrowed a kite...

SInce you mention Ice I am going to assume you mean a frozen water surface. If you are truley on ice then kite size difference between you and your lighter friend will not be as important becuae there is so little friction. If you were on water, or soft snow, then kite size will make a difference with your weight. As a heaveir (then your friend) rider you hace more mass to move and should need a bigger kite to do so, but when you ride on true ice so much changes becuase there is so little friction and it is very easy to make aparent wind., I hoipe this helps, In softer deeper snow, More friction and you will need a bigger kite then your lighter friend, On ice it will not make as much of a difference if there isn't much friction. On the water you would need a bigger kite for sure!

I would get a 13! You wont ever need a kite bigger than that on ice. I ride my 13 almost all the time in the winter.

Rare for us to get sheet ice, but we definitely get hard-pack if it doesn't snow for a few days or if it blows like stink for a day. Soft powder days over 4"-5" are rare, and it's such a slog just to get to where you can set up your kite when it's like that that we never bothered last year.

Is a direct comparison of size:weight ratios close enough? Or are there some other factors that seriously affect the power of a kite (like being bridled vs 4/5-line, or something more technical like the aspect ratio)?

I fly on the lakes here in winter quite a bit and 7-9 knots is typically frustrating with a open cell foil or LEI. You can, with working the kite and a little luck get some speed up on the snow and create apparent wind.Then you're good.

The problem here in the Midwest is lulls. LEIs Hindenburg, my Frenzy's fall in a pile and require staking, walking down and sorting them out. I popped for a 19m Flysurfer Speed 2 SA. I'm selling off a couple kites to pay for it but I hope to have a lot more fun than frustration this winter.

pretty much use a 10m all winter with the occasional storm day on a 6m.......................come the think of it, I use the same set up on water in roughly the same proportions!

Even back in the day when I had a bigger quiver, winter only required a one kite quiver with the occasionally really windy day.

The monster flysurfers will for sure get you a bunch more days, but light wind has less appeal for me than it used to. Especially when it usually only takes 10 knots on snow to have fun with a regular size kite.

I'm about 170lbs and I fly a 9 - 13m combo in the winter in what sounds like similar conditions. I f you wanna get out in lighter winds I would for sure go bigger. 13-15m definitely. I fly foils in the winter but I wouldn't be too worried about having a big LEI cause at least you'll have lots of depower if the wind picks up. Although I can get going in less, 10 knots is usually the threshold when it actually gets fun.

Our condition here is frozen lake with 5 to 30 cm of snow on top of it. Mostly the snow is hard packed but for some weeks we may have powder. Wind is usually in a range of 6-20 knots with some days up to 30 knots.

On clear ice people are using the smallest possible kite they have, especially it they go out with skates it is small foils or 4 to 7m2 LEIs. When there is some snow or it is hard packed there can be still used smaller kite than on water but the edge can be kept easier so bigger kites can bu used. With lots of powder it requires the same power than in water.

With you weight (93kg) kiters here are using 10+ m2 open cell foils, 15-21 m2 Flysurfer Speeds or 14-20m2 LEIs in about 6-12 knots. 12m2-16m2 LEIs or 15m2 Flysurfer ´Speed or 8-12 m2 open cell foils in about 10-18 knots. And smaller from there.

It is also depending on what you want to do. Just for cruising you can go with 14m2 LEI even under 10 knots if not too much powder but if you want to do bigger jumps/tricks there you need to go to a bigger kite.

Go Big on those POW days 17 to 20M is a must, Dont be scared a bigger the kite usually means safer, as they dont move fast or are twichy, As long as your not riding in winds they are not designed for. If you have 2 ft of fresh POW, note that;
1. If theres to much wind snow piles up into drifts. In high wind the snow piles up were you dont ride!
2. You need lift to get you up and riding.
3. When downwinding it, its real nice to just park the kite and butter it up.

Lots of old 20m LEI out there for cheap, put a 5th on 1 or 2 lee edge struts, just push some line through for a attachment. Kite will reverse relaunch better than anything out there.