Brucey wrote:Where the diamond frame is an example of fairly convergent evolution for upright bikes, when you look at recumbent machines, there is little similar convergence, and things change enormously with relatively small changes in intended application or designer's whim.
Here's a thought. Just my own thought.
In late Victorian times, the "discovery" of the bicycle chain (and drive) allowed the huge, and immediate, transition away from the Ordinary bicycle. It's often depicted as a move to the Safety bicycle, in the diamond frame configuration that we all know and (some of us) love. But, historically this wasn't quite the case. The Victorians came up with just about every configuration that you could imagine - two wheel, three wheels, two riders, three riders, one rider and two passengers, side-by-side, semi-recumbent tandems, triples, four wheelers, sun canopies. And some of our current engineering
concepts were actually engineered then, albeit with poorer materials and technology.
The "Safety" emerged triumphant for a number of reasons - it was easy to master; a whole range of shapes and sizes could ride it; it offered everyday practicality in a number of guises; it was simple in design; and (crucially) the simplicity allowed it to be mass produced relatively cheaply. At a time when working people had no independent transport, this was a godsend, which opened up new avenues for work and leisure. It went down a bomb....and relegated all other possible developments to the shed out back, to rust away and be forgotten. (metaphorically speaking, of course).
In the past 30 years, or so, there's been a re-emergence of ideas that were thought of as lost. For example, a wide variety of cargo bike configurations can been seen, especially in Northern Europe (I can't speak for USA). Electric bikes are simply a reworking of the concept of sticking a small engine in a bicycle frame, which was the way in which the motorcycle industry was born. And, of course, there's been the revitalising (and move into series production) of recumbents.
To my mind this period of rediscovery of cycling configurations is not confined to the recumbent and all the excitement, innovation and effervescence in that scene. I believe it's a return to that Victorian period in which people with ideas put their necks on the line and manufactured their creations. They hoped to make a profit (of course), but found that it was only the D/f that would do so. But, what we have today is a market place where more people have more disposable income. So, there are niches for smaller production runs (of recumbents; cargo bikes; handcycles; trikes; semi-recumbent tandems; etc) in which people will pay more, because they can afford it.
I agree with Brucey, the D/f thinking has converged, and recumbent thinking is (at present) multi-faceted. But, I would go further and say that all non D/f cycling is currently broadening its spectrum. Personally, I find this most delightful and stimulating, even if I do sometimes go into a museum to find a Victorian exhibit that is currently on the market as "new thinking".