One of a the few truly-foldable bicycles, the Brompton distingushes itself by its extremely compact size, nearly- instantaneous collapsable capability (demonstrated on subsequent pages), and, when folded, the ability to be rolled around on built- in castor wheels like a suitcase, rather than always having to be carried by hand. Unfolded, it rides like an ordinary upright bicycle. It comes in 3-speed- or 5-speed  Sturmey Archer  hubgear versions, the latter of which, even with 16" wheels  (ERTRO 37-349),  provides a range of 41 to 92 gearinches.
    Folded down, it fits into a bag of 56 x 55 x 25 cm size, ergo a volume that does not raise objections when taken aboard public transport, it actually falls within the rigorous limits for carry-on luggage on the London Tube as well as subways, trains and busses practically everywhere.

    A few hard measures from the Brompton brochure: