DrkAngel said:
The use of a drop front, basic fender might have just as much, or better, effect.
Consider that, at 30mph, the top potion of a tire is producing 60mph wind resistance.
Especially with a knobby tread, the determent is severe.
The use of a "fairing" covering the top half of the tire and ideally encompassing the front forks should provide a marked aerodynamic advantage.
A similar rear wheel fairing should produce a much less noticeable improvement but will keep the bike looking ... more even?
Fitting the unit to the front wheel was very difficult; I could not cover more of the front wheel without having wheel rub all the time. The way I have it set up is imperfect but it is the best I could do given the layout of my bike and what I had to work with.
Contrary to what you say, my original trial was with a front unit only; when I added the back unit the beneficial effect was doubled. Also, taping the spoke bases to reduce turbulence has a noticeable benefit.
I have found from my experiments that performance cannot be predicted based on how a setup looks in a picture; only actual use of a product will determine its effectiveness. This bike used to have a 350 watt mid drive motor. I recently upgraded to a 450 watt motor with the battery and all other parts remaining the same. The only difference is the addition of the wheel fairings to the 450 watt motor. The laws of physics dictate that battery range should be 22% less with the more powerful motor but in reality my range is 7-8% higher than it used to be. Consequently, I credit the wind fairings with upto a 30% increase in range. Since the fairings cost almost nothing to make, I would consider the improvement to be phenomenal and I think this may end up being the holy grail of e-bike aerodynamics. Top speed is also about 5% higher and acceleration to top speed seems to be faster and easier.
I find that most people scoff at this idea because of how it looks and their own preconceived (expertise) on the subject of aerodynamics. It is their loss that they are unwilling to even try it out. Bill