Windshield dynamics

[easyrider]

I noticed at around 45-50 mph there is a significant amount of head wind . I have the stock short version Honda windscreen. Will the tall version make a difference or create a sail affect. Advantages / Disadvantages??.. Appreciate thoughts , and experiences. Thanks

[Oyabun]

I have the medium sized Kappa (exactly the same as the medium givi) and it actually gives a slight 3-4kmph increase in top speed by providing a bit better aerodynamics. I'm about 178cm and it gets the wind off my chest fairly well, but keeps enough wind on my helmet to clear it from raidrops above 45-50kmph. However while the stock short screen has a clean airflow this medium screen causes quite a bit of turbulence or buffeting just around my ears or chin. If I raise myself a bit on the seat it gets slightly less noisy. Not really comfortable above 90kmph on the longer run either way.
I have learnt that the tall screen might clear your entire head from wind, but if you ride more than ocassionally in rain it might be annoying that the large screen does not clears properly by wind - and it has quite bit of drag also.
I'm sure more peeps will chime in.

[j.d.b.]

I have the tallest National Cycle that comes up about mouth-height on me (173CM). It keeps the wind to the top of my helmet. It doesn't behave as a sail but, I did give up about 5 mph of top speed.

[easyrider]

Since I am 5' 11" I think that the tall windscreen would be best suited for me. I don't think I will lose speed because my body is a bigger drag than an aerodynamic smooth plexiglass deflector,wouldn't you think ??Might help with the speed ?

[j.d.b.]

You can try an A-B-A test as I did. At my height(5'8") the speed loss is the all the windshield, as tested. Even the "cleanest" bikes are still "dirty" aero-wise.
I've always liked the comfort(and shielding from stones) of a fairing and the 5 mph price is acceptable. I don't take mine on the e-way, anyway.
"Enjoy the ride, it's one-way as far as we know".