Spanish designer José Hurtado started out as an architect before shifting his focus to industrial design. Among the projects in his newly-launched portfolio, one project in particular jumped out: the "Twist" bicycle concept.
Twist [is] not just a bike, [it] is a union between people. Sometimes a change of direction in your life helps you to find yourself. With Twist, the change of direction will lead you to meet and enjoy the people, like you, who love cycling, mobility and [a healthy lifestyle].
The bike is designed to be reversible; hence, the unusual shape of the frame and positioning of the handlebars and saddle.
The bike frame has a single arm that holds the wheel on two points, thus preventing movement and anchoring it securely. The frame is crossed by the pedal system rotating inside for the bearings. The turning circle of cycling is the same as conventional bicycles.
Thus, the hubless wheels aren't just for show: they serve as a point of attachment for a second frame, such that the tandem bike becomes a mirror image of itself when viewed in profile:
At first I thought that the concept could be extrapolated to accommodate any number of riders in a theoretically infinite daisy-chain, but given the shape and attachment points of the fork, alternating frames would necessitate a third wheel (in a manner of speaking), which could accommodate two forks, one on either side.
This, of course, is also assuming that the hubless wheels, unorthodox drivetrain, reversible frame and the 'twisting' mechanism itself are practical (or at least feasible) alternatives to those of the tried-and-true double diamond design.
Also, any ideas about a reliable braking mechanism for a hubless wheel?
Additional images and details via Hurtado's website.