I switched to SPD-SL from SPD about 6 months ago. I'm using the 6 degree cleats. After a few rides I thought I had the cleats dialed in. Now, however, I'm starting to get sore knees. Nothing major yet but that's what I want to avoid.

If it tells you anything, they are not really sore during the ride, but are for a couple days after. My winter rides are around 90mins on average.

Are there any tricks or tips that can help me identify if I should go more heel out or heel in? Or even just move the whole cleat over? I've tried just walking and finding my natural position but that looks close to what I have so not very telling. Obviously I can just try something, but it took quite a while to notice anything and it might again. Thanks.