Folding Bikes are small-wheeled grownup bikes easy to bring up the stairs and park in your house, folded or not, to continue watercrafts, RV's, bus and even more. Extremely low frame simple to step in and out for older bicyclist.
1 speed bikes are for taking a trip short distances in a primarily flat community. It will take less than 6 minutes by bike if you can walk there in under 30 minutes. Bad for increasing long distances or steep hillsides.