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…I've been performing a lot of experiments in an effort to nail all this down. I've built various sizes and shapes of lowers, and just today I tried several sizes of extensions to increase the height of the Roadster screen. As a result of all this, I can tell
you that insulating the rider from buffeting requires a thoroughly coordinated approach…

A man after my own heart. I have done ridiculous amounts of fiddling with screens. I’m happy-ish with my setup but always interested in improvements.

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First, the windshield must be tall enough to create an airflow over the riders head. That sounds easy until you realize that no one seems to know exactly how tall the windshield should be to accomplish this. One reason is that the windshield's effectiveness is degraded by any updraft from below. In addition, if the height of the windshield is marginal, its effectiveness will be further degraded by the rider's helmet. Simply put, protrusion of the helmet into the airstream causes the frontal blast to move downward (in the case of the Roadster, into the riders eyes). Assuming the rider wears a 3/4 open face helmet with no face shield (worse-case scenario), a windshield at least 18" tall will be needed in order to move the airstream above the helmet. If sporty looks aren't essential, 20-22" is even better, and I would say essential if you'll frequently have a passenger. In any event, the taller the windshield, the more room for error you'll have in the other areas of the design.

Ok but… at 18 inches you’re probably looking a bit above the screen, at 20-22 even a 6 footer is looking through it. The downside to that is your vision is obscured in rain, especially with road spray mixed in. Your point about the effect of the helmet being even a bit in the airstream is interesting.

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The second thing that's required is to eliminate the updraft by creating an effective airdam below the windshield. This requires large lowers that no one currently sells. The lowers must extend down to within an inch or two of the bottom of the lower fork shrouds and be sufficiently wide (about 8") to prevent air from hitting the front of the tank. They must also extend up and meet the bottom of the windshield with very little gap. The latter is especially critical if the lowers are raked back at an angle like the forks. Air hitting the lowers will be directed up to the rider directly through any gap at the bottom of the windshield, causing severe side-to-side head buffeting.




Here I have to disagree. I think the lowers act to break up the airstream that would otherwise flow up behind the main screen rather than just extending the windshield further down. I have the standard Memphis shades lowers but I have tried much larger ones with no noticeable effect. If you look at the picture below, you’ll see that my lowers are nowhere close to the main screen but the difference with and without is night and day while the change to larger lowers or fitting them closer to the main screen is marginal.




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Finally, the gap between the bottom of the screen and the headlamp bucket must be minimized. Windshield effectiveness is particularly vulnerable to this. Air entering through this gap is directed upward (probably due to the curve of the tank), degrading the envelope behind the windshield. In my case, the gap is nearly 1". A curved piece of acrylic wil be needed to remedy this..

I may have been lucky in this area. My first Memphis Fats was too tall at 19” and, just by chance I chose to have the headlight cutout extended up 2” rather than crop the top. The result of this is a close fit to the headlight shell and a screen that extends down to the bottom of the shell. As I look at the pics of the roadster screen though it looks like a fairly tight fit so I dunno… Where do you have the 1” gap?


One thing you don’t mention that I do think is critical is the angle of the screen. The Memphis shades hardware has a lot of adjustability and I’ve been able to tilt the screen back quite a bit more than (I think) the roadster goes. The roadster’s brackets don’t look very adjustable but maybe there’s some play somewhere you could try out. I have mine tilted back as much as I can get even at the expense of bending my speedo almost dead upright. While I might imagine that a 45 degree angle would be best, the furthest I can get to is the angle of the forks (which by rule of thumb is also said to be a good idea).

So, there’s my two cents. I’ll be interested in pics, side and front of your experimental setup and your continued dialogue. It’s too cold here now for further experiments but I’ll be continuing research over the winter and I may make changes before the long ride to Georgia next spring. Although I still have some hope for the Darth Fairing Convertible project.