mpg vs windshield size/type

I've read that windshields can have a significant effect on fuel economy, so I figured I'd ask what experiences you guys have had with different size windshields. I believe one of the many reasons why motorcycles get disproportionally worse fuel economy for their size/weight vs cars is aerodynamics, meaning that your body sitting up in the wind has a terrible coefficient of drag. In theory, a properly designed windshield could decrease wind resistance for the same amount of frontal area. For example, the fairing and windshield on a sportbike, vs a naked bike with the same seating position, same handlebar height, etc.

But what I'm wondering about is how does this actually work out in reality? On the maxim-x site they say "a large windshield will have a horrible effect on your gas mileage no matter how you adjust it". Thing is, most cruisers you see going down the highway do have fairly large windshields. I don't see how the addition of a windshield of the same size to one of them vs a maxim x is going to have a lot more significant effect on the mpg of the maxim x.

I installed the "mohawk" windshield from national cycles on my 85 maxim x. I think it actually looks pretty good, and it did cut down on the pressure on my chest and shoulders. However, with the seating position and handlebar height of the maxim, I still feel a lot of wind at the top and sides of my shoulders, and it doesn't block any wind for my face/helmet. I really would like to cut down on wind induced fatigue a little more.
So just looking at the other windshields that come up as options for the 85 xj700 maxim, https://www.nationalcycle.com/catalog/category/view/id/3988 they have quite a few other windshields. Out of those I might lean toward the "street shield", but I don't want to go any bigger than necessary. I'm a little apprehensive about potential adverse affects on mpg, buffeting, etc.

Any input or experience is appreciated,
Thanks

 

ear plugs help a lot with fatigue.
think of the wind shield like it was your chest. it will make very little difference what the wind is hitting, curved shield or you as far as mpg goes.
mpg should not be a big factor in your choice of a wind shield, the windshield is for your comfort and safety.
the biggest factor you need to consider is how and where it mounts.

 

Full fairing on my xj750. I get between 42-50 depending on wind, speed, and riding style. Average around 44.

 

I get 42 mpg without any style windshield on my XJ750J.

 

You guys are pretty much confirming what I thought, that a windshield won't adversely affect your fuel economy, if your body is the same amount of frontal area as the shield. The national cycles street shield that I'm leaning toward has a 4 point mounting system, two points that connect to the forks, and two that connect to the handlebars. It's polycarbonate with some type of hard coating, (not acrylic), and doesn't have those flat "H" shaped metal pieces that most windshields have, that I absolutely hate. I wear earplugs all the time at work, when driving my old cummins swapped chevy pickup, while mowing my lawn, etc, so it's no big deal to wear them riding, but the wind is really what fatigues/annoys me, more than the noise.

 

most of the "drag" on something moving through the air is from the vacuum behind the object. splitting the air isn't as important as putting it back together.
big trucks have those bubble things behind the cab, bicycle helmets with the long point in the back, small plane wheel pants, drafting in nascar, racing canoes are wider toward the front to have more distance to put the water back together.
you need to get your head in the bubble of vacuum behind the windshield, check out this place https://www.laminarlip.com/

 

I wonder if one of those laminar lip universal attachments would work on my street shield. The street shield isn't quite tall enough, most people say the top of the windshield should be about nose height, mine is about at my chin, I guess. I get a little buffeting, but overall the reduction in wind pressure is nice.

 

i have one on a bmw k100rs, no windshield, just the lip. the bikes too hot in the summer and i'm too cheap to buy a bmw windshield.
the lip alone gets my head out of the wind but my chest still gets the breeze.
the curve makes it act bigger than it is