The Greatest Invention Ever

We evolved, for perhaps 2 million years as vertical bipeds without ever discovering that the forward step motion of the feet could be extended into the more productive circle. The invention of the wheel is often cited as the start of human technology but surely finding the mechanism by which the wheel could be integrated into the natural movements of the body is the real breakthrough.
The further application of sprocket mechanisms on a pulley, whereby a rapid small wheel turns a slow big one, is surely an improvement on the original genius.
It is the same sort of trick that was used to lift weights, changing the ratio between distance and effort to make heavy loads manageable - I was taught formulae for describing this in maths classes - but what the bicycle carries is the very person who operates it. It's not like using a pulley to lift dead weight and leaving the worker standing in the same place. The driver is the load. The cyclist is the operator and the cargo. Brilliant!
Indeed, cycling is an improved application of the legs over what nature and devolution devised, for it makes use of the return step.
Previously the only reason to lift the hind foot and put it in front again was to enable another step. On the bicycle the foot produces movement when it is drawing and when it is returning, especially if you were toe-clips or cleats, which no thinking cyclist would leave home without,  wanting to enjoy the full marvel of the best machine ever made.
Evolution had no intention of enabling the legs to piston, to produce a circular motion. It had bent the knees to help us walk and climb; it had strengthened them to support the upper body, not to allow us to prop that body in a saddle and divert that force elsewhere. Well, perhaps it equipped us with a downward kick to help us defend ourselves against predators chasing us up trees. Is there a single other instance of a body evolved to one purpose being so deftly put to another? Well, yes; the horse. You can't look on a horse now without wondering at how unfinished it appears without a rider. But a horse isn't a mechanism, a product of human inventiveness. It is an enslaved beast. The food you give it provides no return in your own body and the maintenance costs are huge compared to oiling a bicycle.
The bicycle's only fuel is the food the rider eats. What could be neater than that? It is almost like cheating in the game whereby we biped primates learn to progressively manage the resources of the Earth and take off into space. Only a car driven by expelled breath would approximate to the efficiency of the bicycle.
And when you consider that cycling, that is, burning food to make energy to propel yourself along, simultaneously makes you physically fit, giving the body the best possible advantage of that same food -- surely this compares to stealing fire from the gods? Nothing we did in the ancient world ever so justified the myth.
And yet the bicycle has not had the credit it deserves. The history of the industrial revolution has it that every great leap forward was grounded in the discovery of coal or oil. That was the incentive for people to come off the land and build cities.
But what do we see in the footage from modernising countries today but rivers of people on bicycles flowing over the roads to work? The factories would never have functioned if the bosses had been waiting for workers to get there on horses and donkeys. There should be a statue of the bicycle in the heart of every industrial city.
Yet, for all that the bike is a machine, and, I argue, the quintessential machine, the best machine ever devised, being the one that converts natural human movement into improved locomotion without fuel, it is widely viewed as something else -- a style statement.