Where was the knee pain? My favourite book: (Long Distance Cycling by Edmund Burke and Ed Pavelka) suggests you point your toes in the direction of the pain and it may go away. Point them out for a pain on the outside and vice versa. I use toe clips to give me as much movement as possible as I have only one meniscus in one knee and it sometimes hurts, although it's better cycling than standing or walking!
Good luck with the free wheel. My wife has ditched her gears in favour of a SS and loves it.