first lets start with proper seat height and adjust from there. measure your inseam while standing in socks and straddling a book spine to represent the bike seat. the distance from the floor to the top of the book will be your actual inseam. take this measurement and multiply it by .883. this will be the measurement from the top of the seat to the center of the bottom bracket, as measured in a line down the seat tube. your proper baseline height. start with this and report back. in general however, knee pain in front and below the patella indicates the seat is too low or too far forward, maybe both.