Really, the concern about what goes *into* the wind is a significant concern as speed increases. It becomes more
important than what happens to the fluid (air or liquid) after passing over the object as an object approaches supersonic or hypersonic speeds. Let me write that one more time to emphasize it: supersonic or hypersonic speeds.
Up until then, it's important to have something heading into the fluid with minimal frontal area, but on balance it will be more effective to ensure that the flow of the fluid around the object is as smooth as possible. Therefore the majority of 'aero' considerations are not necessarily for what's headed into the fluid, but more concentrated on how the fluid moves around the object and in what state it leaves the surface of the object (disturbed or calm). Of course, making sure that the fluid flows smoothly around the object means that the front shape heading into the fluid also needs to enhance the flow of the fluid, which usually results in a 'rounded' frontal face or edge to some degree, but it does not necessarily need to be small.http://en.wikipedia.org/wiki/Aerodynami ... l_concepts
So when you start nearing supersonic speeds on your bicycle you should be seeing aero shapes more
concerned with the frontal area heading into the fluid.
In the meantime, just go ride your bike.INB4 someone says "Air is not a fluid". Air is a fluid. Period. Water is also a fluid. The difference is that one is a fluid substance in a liquid state, the other is in a gaseous state. A fluid is a substance that has no fixed shape and yields easily to external pressure.
Also, if you need a quick mental example of the difference in shape concern of a subsonic object vs a super or hypersonic object:
Subsonic = Jet Airplane. Airbus A380, for example. Not very pointy, but very aero for shape as the fluid moves around the object.
Supersonic = think of a rocket. They have a sharp front tip, but usually the end is rather abrupt and not designed to care too much about turbulent flow. The primary concern is for breaking the density of the fluid (air) as it is compressed by the object's forward movement.
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