The Brompton is a famous and popular folding bicycle from the UK which is said to have the smallest dimensions when being folded. It has 16" wheels and three folding joints.
Its community is so big that there are even national and international competitions. The races have a Le-Mans-like start, i.e. the participants need to run to their folded bicycle after the starting shot and then unfold it.
There are also competitions in folding the bicycle. Record in 2014 was 7.19 seconds.