Originally Posted by Neist
I still say single speed would be best though. If you give someone who is not customed to riding bikes, they could get into bad gearing habits and potentially blow out their knees with too low of cadences.
When you're just teaching them to balance, you put the bike in a good gear and tell them not to touch the shifters at all.
Later on you introduce them to gearing and supervise to make sure they are learning the good habits.