One benefit of folding bikes , in N+1 situation,
you can always find a place to put it in your House.

In the car Boot and so forth..
I have 2 bikes , both with a 47 wide tire
Diameter matters .. the difference between
the 26 and the 20 " wheel is a world apart..

Go Fast Bike you have the skinny tire,larger rim 451 20"
like Bike Fridays Pocket Rocket.

There are also NonFolding small wheel bikes in mini-velo category
popular with Asian riders in small apartments . the smaller wheel just Occupies less space.
Shimano , naturally has asmall wheel Cassette & hub , the Caprio.. 9-26t to run the regular cranks
like 53-39.