That is interesting to know, Mapbike. If someone is running a coaster brake rear, that is an easier modification to do (otherwise someone will probably have to weld new brake bosses or a brake bridge to the frame) . It will slacken the steering angle a tad, and lower the pedal clearance a couple inches. Did it seem to make much difference to you when steering? Did you run a tire wider than the 26" one you had previously?
I've seen a few people put 20" wheels on bikes originally with 26" mtn bike wheels. They were used like mini-velos for riding in the city. I don't know if I'd want to go 30mph on 20" tires though! Rough!
20" wheeled fixie city bike