my 2 cents - cleat position was a huge deal for me, clipless gave me knee pain when I first switched. Tried shoe shims and even angled cleats - no help. In the end through trial and error I learned that I need my cleats all the way at the front of the shoe, I guess I pedal more with my toes than my feet. Whatever the reason I've been pain free for a year. In my case I went back to toe clips for up to a month until the pain went away, then tried a new position. Took a while because everything I read said not to put the cleats forward