Originally Posted by 12boy

The guideline I use for seat height is that when sitting on the saddle my heel should just reach the pedal on the downstroke. The reason behind this is I put pressure on the pedal with my leg less bent which stresses the knee less. Too low a saddle feels like walking in a crouch which does load my knees a lot more than a straghter leg position. I also find that the front and back position of the seat also affects the way my knee engages, and on a new bike I start with the saddle set so that if the back of my elbow touches the front of my saddle my fingertips just reach the handlebar. Since not all saddles are the same length and some bikes require a more or less bent over position I adjust from there. However, this does not mean you havent damaged your knees and don't need to see a doctor.