Windshield Turbulence

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vroomr
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Windshield Turbulence

Post by vroomr »

Musings on turbulence.

My ’07 came with the little sport windshield, which provides wonderful air conditioning in the warmer months, albeit with a surfeit of insect protein plastered on my shoulders and face shield. Although my helmet is within the airflow, the flow is smooth and comfortable.

In the cooler months I put on my old Cee Bailey’s high shield, which protects my torso nicely, but which sends a turbulent flow to my head. This turbulence has become unbearable with the recent purchase of an Arai Signet-X helmet, whose dark overshield vibrates my view to blurriness, and whose excellent ventilation ports transmit what I’ll call “acoustic rattle,” annoying even with earplugs; neither the blurriness nor rattle occur with the sport shield.

So, I’m wondering how to get good cool weather wind coverage without turbulent air hitting my head, while still looking over the top of the windshield. I see that CalSci shields have openings in them to get some direct airflow up the backside of the shield, which makes me think about drilling holes in the Cee Bailey’s to see if that would help--hey, what have I got to lose?

Also, while I was dismissive of BMW’s short “high” shield for this bike, maybe they were on to something, and perhaps that shield is high enough to provide some protection while still sending smooth air to the ride’s head, so maybe I should consider that shield or something of similar height.

Your thoughts, please.
Richard
Terry Kronlund
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Re: Windshield Turbulence

Post by Terry Kronlund »

I added the MRA adjustable spoiler to both my wife's and my windshields. The adjustability is awesome to dial in what you want. I can have my modular helmet open all the way or closed. I only close mine when in high winds or when turbulence caused by semi trucks. Oh! and whenever I really feel like twisting the throttle.
deilenberger
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Re: Windshield Turbulence

Post by deilenberger »

There somewhere here is a LONG thread on windshields. I'll summarize it as best I can:

1. CalSci with the holes are no better than the Cee Bailey - perhaps worse. I was the test subject on them - and I eventually threw it out. It simply didn't work.

2. There are two versions of the Cee-Bailey. If you have the original - the turbulence is directed at your head. I found their tall shield too tall, but that's me - I'm short. I can tell you how to make a Cee-Bailey work. In a bit...

3. The BMW big shield (aka Touring shield) isn't good for much of anything. The air from it hit me mid-chest, and bugs and other debris was still hitting my helmet. It also was noisy and turbulent.

OK - I assume on the '07 that you have the BMW tall shield mount for your CeeBailey. What you need to do is step the bottom mounting point on the mount out about 3/4"-1" from where it is. That tips the top edge of the shield back toward you, and the air no longer is pushed up over the top edge, it's pushed up and continues up for some distance above the edge. It separates more smoothly from the edge.

The turbulence comes from the air dropping into the vacuum formed behind the shield and tumbling as it does this. Moving the bottom out also opens up the bottom, breaking the vacuum behind the shield, so air comes up the inside of the shield - also helping to direct the airflow up and off the top of the shield in a "laminar" flow. You can easily prove this to yourself whilst riding. Hold your left hand out so your palm is facing directly forward. How does it feel? Then tilt your hand around 45 degrees - how does that feel?

On my R12R's - I've done this on both of them. With the tilt-back, with a short CeeBailey (found I much preferred it for various reasons, even mid-winter) - it moves the "bug line" from mid-face-shield to over my head. There was a distinct line above which bugs would splat on my faceshield. That line now is gone - and I only rarely get a huge bug on my shield - smaller ones are all swept up over the top of my helmet. There is still air hitting the top-vent of my helmet (Schuberth Concept3-Pro) - but just. If I scrunch down just a tiny bit - I can hear the difference in airflow. I can run with my helmet shield cracked open without it shaking.

So - that's the trick. Tilt the mount and shield back a bit.

Easy to do on the pre-camhead bikes.. (can be done on the 2011 and newer bikes, just takes a bit more engineering..) There used to be a "Don C" block available from one of our members here. He made them and sold them for about his cost (he certainly wasn't getting rich making them) - they went under the bottom mount point, and you just used longer screws to fasten the clip that holds the bottom of the mount in place. You could do the same by cutting two lengths of aluminum tubing - say 3/4" long - and using them as spacers to move the mount out (with longer screws.) The top mounting point stays about where it is. No modification needed for it.

LOTS of us here used the spaced out mount. And some of us who bought newer R12R's also came up with ways of tilting the shields back more.

I've finally gotten rid of most of my spare shields. For a while I had about 6 of them hanging around (including 3 sizes of the original CeeBailey shield) - I'm down to the one that I like. I think it's the 14" CeeBailey shield - the shortest of the bunch. It works just fine for me once tilted back.
Don Eilenberger - NJ Shore
2012 R1200R - I love this bike!
vroomr
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Re: Windshield Turbulence

Post by vroomr »

Thanks for that, I'll give the tilt a try--I do recall some of the stuff you mentioned from way back. My guess is that the tilt accelerates the air flow, and the turbulence sets in further back. Funny, things seemed fine until I got the excellent new helmet.

Sometimes I duck behind the Cee Bailey and marvel at just how mechanically quiet the bike is.
Richard
vroomr
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Re: Windshield Turbulence

Post by vroomr »

You know, I think it's just time for a new windshield, because that second generation Cee Bailey's is just too short and too narrow, and I want some more comfort as I slouch into senescence. So, what do I get? That CalSci got a very bad review here, but I see that Parabellum is still in the game with two choices. Does anyone have experience with that brand of shield? Is there anything else out there? TIA
Richard
Terry Kronlund
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Re: Windshield Turbulence

Post by Terry Kronlund »

I love my Parabellum. I have a 18 or 20 inch tall shield, can't remember which, it is not tall enough so I put the MRA adjustable on it. The turbulence hitting my chest is much much less and when I ride in the rain my crotch distant get soaked. The adjustability is awesome with the MRA. It makes for an expensive setup but I got the parabellum cheap on eBay. It even was painted the color of my bike. How lucky was that? I wish I could remember the height of it. My best guess is that it is 18 inches. I am 5'9 with a 32 inch inseam. If thats any help. I would measure the height but I brought my GS to Mazatlan and the R is at home in Seattle. I went from a Goldwing to the R and wanted more wind protection, since I am spoiled by the Wing. I wanted a cooler ride in the summer also. I would say I ride 10 degrees cooler on the R than I do on the Wing during the summer. 10 to 15 degrees warmer during the winter months. The GS is new to me and the Wing is the odd bike out. My wife rides and R so two up riding that the Wing is great for is now not necessary for our long cruises.
vroomr
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Re: Windshield Turbulence

Post by vroomr »

Well, I certainly note your enthusiasm for the MRA. I must research. Thanks.
Richard
vroomr
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Re: Windshield Turbulence

Post by vroomr »

Just picked up a used MRA from a neighbor and experimented a bit with it. The hand-in-front-of-face test seems to indicate best results with the MRA up high and well raked. I'm not in still air, probably because my windshield is so narrow. I may yet get another windshield, but the MRA seems to help. More experimentation with height and tilt is in order.
Richard
motoracer8
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Re: Windshield Turbulence

Post by motoracer8 »

The trouble with most motorcycle windshields is they are too far away from the rider and almost vertical. Designers fit shields at the same angle as the front forks because they look better. One of the best shields BMW put on a motorcycle was on the early K100RT's. The shield swepped back closer to the rider and was very effective. But riders complained and said the shield was too close to their face. The quietest ride is with no shield at all unless its a barn door like on a Harley or a Gold Wing.
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foobar
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Re: Windshield Turbulence

Post by foobar »

I could not take the turbulence of the BMW touring (Cee Bailey) wind shield and switched out to a PUIG "Naked New Generation" (6488W). Big improvement.

The Cee Baily has a lip that sort of curves away from the rider, which I would think would induce a tumbling motion in the airflow moving over the top of the wind screen. One me, this would hit the top 1/4 of my helmet and would start to reverberate badly above 85-- no hate-- I am in FL and even Kias are going 80 on these long straight interstates. The Puig is shorter and angles back towards the rider and curves down. The airflow coming over the top of the screen is smoother. My helmet is now 100% in the non-deflected airflow. Some may not like that. However, there is no nasty reverb and rides are much more comfortable.

The curve back to the rider is probably the key. Move the air to where it wants to go rather than just trying to block it.
2002 R1150R (gone)
2006 K1200R
2008 R1220R
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