I'm using my Bike Friday to the exclusion of all my other bikes,
a step thru function is gained , because the top mono-tube is low..

Builder, a small company in Oregon, near custom sized.. 8 different top tube lengths
406 20" wheels, so common spare tires too ..

2 product lines, Tikit a smaller 349 wheel is made to quick fold,
travel bike line, has a partial slow fold and knock down combination to use a suitcase
as the bike box on trips. notably those that add a bike surcharge to your airfare tab.