The more I kite the more my knees hurt. What is the easiest style for your knees? Are strapless SB's knee friendly?

What are you using for a board, kite and style?

try to avoid chop. use a board with more flex.
If you like to jump, rather ride a bigger kite to land softer.
If you just go back and forth, use a smaller kite to have less pressure edging.
try a different angle for your foot position, closer, further apart, twist more or less and see what is better.

In my experience knee pain has been directly caused by wrong footstrap placement for your stance and body type.

Experiment with lots of combination of footstrap position for stance width, duck stance angle, and how tight your straps are on your feet.

In general wider stance, more duck feet and looser straps equals less or no knee pain.

Some boards are better than others for knees. For me the OR Mako was really very easy on knees. Or a directional - strapless or with very loose straps.

For me strapless surfboard is way easier on the ankles and feet and probably knees as well since you don't normally jump too much. But it also depends on how fast you ride and the chop conditions so it might not really be better than a twintip cutting through the chop rather than banging over it.

But...
By far the easiest on your body will be a hydrofoil. Totally different, its like starting a new sport (new learning curve), but the smooth sensation of cutting thought the water is awesome. Plus you can ride with a much smaller kite than normal, so there is even less strain on your body.

Try a Shinn Monk, used to have knee pains now my knees feel better after a hard session.

I ride a 140 Mako. I think I have it set up well for me, on a normal day I can go out and not have pain. When conditions are crazy or I'm trying new tricks, I'm in pain. I was thinking I should just start doing the strapless thing but maybe that wouldn't help. Hydrofoil does look fun but I don't think it's for me.

I'm also trying to get in shape so I've been doing a lot of biking. The bike should be the best exercise for them but its still a lot of work. I guess my old knees just can't take it all.

Shinn monk is a great board for dogy knees,balance board is good for knee rehab,builds quad muscle,strapless is much easier on knees,bike is good,stick to flat road biking,build knee up gradully,underground kipuna wave board is like hoover craft on water easy on knees,hope this helps,TONY

Bring in your stance and duck it will help more than you can imagine. If you need some help with pain just regular ACE knee brace with the batons are good for kiting. They won't had the support of a mechanical brace so you will still get to strengthen your knees, but the compression will help with the pain. It's what I use on those days where mine bother me both kiting and wake-boarding.

Yes strapless surf will be the easiest on the knees. I'm sure your stance is just wrong play with it till you no longer get pain and can ride comfortable.

Most knee problems stem from 'twisting' the knee. Ride strapless and you wont twist them.