I've been having some problems lately with saddle height, it either hurts behind my knee which I think is too high, or in front of my knee. I have put it up from the .67 x inseam which I think was a bit low, and am still having a bit of an ache in the front. But, when setting it with a slight bend at full extension, what position should my foot be in? Should it be totally horizontal, toes down heel up, or heel down? And the crank should be inline with the seat tube? It's really irritating me that I can't get it right.