Knee Pain

i may be wrong but i thought a plumb line dropped from the leading knee should hit the pedal axle when the cranks are horizontal, and i go with the old "knee straight, heel on the pedal at the bottom of the stroke.

the plumb line trick sets the aaddle position... i.e. fore aft movement, the heel on the pedal isn't ideal as different shoes have different sized heels, you are looking for a 25-30 degree bend in the knee, which is hard to guess, so you ideally need a protractor type thing (sorry forgot it's proper name) to measure properly