Figure 23 comprises two photographs of a Brompton prototype, one in the folded state and one in normal configuration. The normal configuration has the near horizontal beam with a prominent hinge a little over half way along its length i.e. some way from the chain-wheel but not close to the front wheel assembly. The handle bars are like the Bickerton in that each handle has its own strut connected at the front forks at the beam. They have a V-configuration rather than the more conventional T-configuration. The rear wheel is designed to unlock and rotate under the frame but the centre of rotation does not coincide with the chain wheel and so an extra guide cog has to be used to keep the chain on the chain-wheel. The folded configuration shows that this prototype manages to sandwich the chain wheel between the two cycle wheels but one of the handlebars is on the outside of the folded assembly. Overall, this prototype has a more complex design than the final design and the folded state is not as neat.

 2.3 Prototyping and improving