Windshield noise

[BobbyLeBout]

This is an experiment using a RT windshield behind a sport screen. The sport screen did get painted black on the rear side. No problems at all with the paint. The RT windshield is adjustable using four RAM mounts. The shield could be readjusted in two minutes. Two go to ubolts on the handlebars and two go to the bolts mounting the handlebars. I will post newer pictures when I find my camera.
The problem I was having was that no matter how the shield was mounted I still had wind noise in the helmet.

I was reaching for my GPS and heard a difference in the wind noise. So I started moving my hand around the area above the tank and could make the noise stop when my hand was in a certain positiion. What I found out was the the wind was coming from under the shield not above it or from the sides. I started using my BMW tank bag again and it cut down on some of the noise. I had to use the smaller of the bar backs with the tank bag for clearance.

A couple weeks ago I ordered a Scout Fairing from Parabellum and found out about the long wait. Knowing that the wind noise came from under the RT shield make me feel better about getting the Scout Fairing but until then I need to have a quiet ride.

The idea of the second shield came from Parabellum. The 1150GS Guard Mount shield is the example I used. More pictures soon.

[Dale_K]

A Ducati I used to own had a clever air shield in the area just below the steering head. It was a pleated plastic item kind of like a Japanese fan. The pleats let it collapse and expand as the forks turned from side to side.

[famousperson]

A Ducati I used to own had a clever air shield in the area just below the steering head. It was a pleated plastic item kind of like a Japanese fan. The pleats let it collapse and expand as the forks turned from side to side.

What baffles me is that these designers neither use a wind tunnel in designing these wind screens nor give them much, if any, of a test ride.

Don, certainly among your contacts you should be able to convince somebody to go to the rational trouble to do that before releasing these beasts on us, the unsuspecting public! The above pleat gizmo is the sort of thing they might come up with in playing around with different configurations.

Do any of the people who are having or have had trouble with screens ever give feed-back to the manufacturers? Would the manufacturers care if they did?

[deilenberger]

A Ducati I used to own had a clever air shield in the area just below the steering head. It was a pleated plastic item kind of like a Japanese fan. The pleats let it collapse and expand as the forks turned from side to side.

What baffles me is that these designers neither use a wind tunnel in designing these wind screens nor give them much, if any, of a test ride.

The guy in Florida who spammed the MOA forums claimed to use a wind-tunnel, but he seemed quite nutty in his own way.. (aka - unreasonable - French even. ) Dunno of anyone else besides BMW who claims to use a windtunnel. Supposedly - Parabellum does do test rides. Problem I suspect also has to do with the greatly varying rider sizes/positions you end up with. What works for one person may not work at all for another. Problem is - none of them really "work" for me..

Don, certainly among your contacts you should be able to convince somebody to go to the rational trouble to do that before releasing these beasts on us, the unsuspecting public! The above pleat gizmo is the sort of thing they might come up with in playing around with different configurations.

Wish I had that sort of influence. I have discussed this sorta thing with a few of the shield makers - and most are quite resistant to making any change in a design they currently have in production. I guess a change would be admitting the ones they sold already perhaps aren't really so good.

Do any of the people who are having or have had trouble with screens ever give feed-back to the manufacturers? Would the manufacturers care if they did?

The only manufacturer who really seems to care is CalSci (Mark Lawrence) - he has called me several times, we've had long email exchanges, he's sent me stuff to try. He actually seems to want to make the perfect shield. Problem is - we haven't figured out what perfect is, and he doesn't want to make "hardware" (mounting brackets) which limits things a bit. I will be playing around some more with the test shield of his I have sometime soon - playing with the angle of it - since both I, and someone else here have experienced improvement by tilting it back more toward the rider. Some people have had very good experience's with Mark's shield - me - not so much, but it's likely a dimension thing again (me being short/plump/low-seat/short-arms.)

Sigh.. wish I knew what the answer is..

[AmostThere]

I mentioned previously that I was looking for someone to modify the windscreen bracket. I met with a guy this afternoon that does metal fabrication for high-end race vehicles. He came highly recommended by someone who should know and he has a backlog of over two months. After describing what I want, based in part on research done by Don with Mark at CalSci, he indicated that it was no big deal. Our plan is to cut off the flat mounting tabs that protrude rearward and the U-shaped portion that locates the bottom of the bracket then attach modified pieces that will move the top of the screen back changing the angle (Don's work indicates 37 degrees might be a place to start) which will require moving the bottom mount forward while still keeping the screen close to the instruments. I believe these changes will be subtle enough that the bottom of the screen will not protrude far beyond the top of the headlight. It will be tack-welded on and then I'll test it. If it isn't just right then we'll modify the angle/height until the elusive windscreen Nirvana is reached, do final welding and powder-coating, then enjoy the ride at any speed! I can already hear the obvious question, the one that I wanted to ask immediately, how much? Maybe $150 plus the paint. Ouch, but if I would have known in the beginning it would be BY FAR the cheapest way to go instead of the umpteen different windscreens. You all that have these well-equipped garages may be able to duplicate this approach on your own.

He's going to fit me in at a gap in the projects next week...

[deilenberger]

Doug,

Cool! I'm looking forward to the results!

[BobbyLeBout]

here are some current pictures
At 70 I do not need ear plugs and can hear the engine purring

[AmostThere]

I very much like your report of no noise at big speeds. Can you tell us the angle of the windshield from the vertical? It is a bit of a hassle to measure, you pretty much need an assistant to check it after you are aboard. I made a protractor work with a piece of string and a small bolt for the weight. Don reported 37 degrees was his top angle. I am also interested in the horizontal measurement from the top of the screen straight back to your helmet. It looks like the screen is above the bottom of your helmet so I won't ask about the vertical measurements.

[BobbyLeBout]

I put the smaller windshield on today but it is raining hard and I am tired of riding in the rain to test it. When I test this shield and make a few adjustments I will measure the angle. Because of grade and many other factors I will report on the difference of the shield as compared to the forks. That takes all the variables out of the measurement.

[BobbyLeBout]

The windshield is curved slightly from top to bottom. The lower portion of the windshield is the same angle as the forks. The uppper section of the shield is tilted 4 degrees more towards the rider. As you can see the very top then reverses the angle.

[lucagoa]

Hello,

recently I bought a ZTechnic screen (cost me a fortune in Europe) just to find out that the turbulence around the helmet is too bad. At 130/140 km/hr my head is shaking like hell , at lower speed in any case the wind just blow at eye level resulting very noisy. I do not feel any pressure at chest (at least this is good).
I was wondering if anyone of you have ever tried to add an MRA extension spoiler (https://www.twistedthrottle.com/trade/productview/2710 ) on an after market screen (i.e. Ztechnic, Cee Bailey, etc)

Do you think there may be an improvement? Anyone has experience with this type of spoilers?

Thanks
Luca

[vodka]

Bobby, could I ask where you got the backrest from?? It looks like its designed for pillion. Thanks. PM me if you wish...ta

[famousperson]

here are some current pictures

Wow! What a set up. May I ask how much it cost? With four RAM mounts it couldn't have been cheap. Did you do all the fabrication yourself?

Peter

[BobbyLeBout]

Vodka,
Backrest is from GIVI. I did not want a large top box and GIVI had this small size. Someday when I sell all of these RAM mounts I will purchase a larger top box for travel. This one works for commuting.

http://www.giviusa.com/caschi_borse_bau ... 97&lang=en

[BobbyLeBout]

Peter,
I had two windshields from my R1150RT collection. The RAM parts were close to $150.00 and the BMW parts were less than $75.00 for the windshield mounting hardware.

The idea was to determine exactly where the windshield belonged without purchasing 3+ shields in the process.

The only fabrication was grinding the ubolt heads so they would swivel freely.

I have ordered a Scout Fairing from Parabellum that will arrive in July so this is just temporary. Then I am going to pack up everything and ship it to anyone who wants to try it out.
Bobby

[GOTJ]

Bobby,

I didn't read your original post closely enough and didn't notice that you had found that the wind coming up what I call the "Wind Tunnels" could be one of the sources of helmet noise. I discovered the same thing and came up with a Proof of Concept solution that is extremely inelegant. Attached are two pictures showing the tunnels and what I did to block them. I have found that this almost eliminates that noise. Now I am trying to come up with a more elegant solution but I am going to keep using this until I do. The tube doesn't interfere with the fork movement because it just flexes out of the way.



Wind Tunnels


Wind Tunnels Blocked

[Mollygrubber]

Now THAT is something I didn't think of trying. Lateral thinking indeed!

Let's file a class action lawsuit against BMW for money wasted buying multiple perfectly functional windshield setups...

[deilenberger]

One tiny thought for everyone who is investigating airflow.

You can feel turbulence. Just like it shakes your head/helmet - if you put your hand in a turbulent stream of air - it shakes your hand.

I doubt very much if without some sort of all enveloping egg-shaped-thingie(tm) that you could eliminate all turbulence on a bike. What you can do is try to determine where the turbulence that is actually bothering you is coming from. I find helmet turbulence annoying. Turbulence on my lower legs - less so. Turbulence on my ample tummy - less so.

In playing with about 7-8 shields of various sizes/manufacturers/shapes now - I have found the worse the turbulence off the top of the shield is - the more annoying I find it. My goal has been to reduce THAT turbulence, even at the expense if needed of additional tummy-turbulence(tm also).

I think somewhere WAY up in this thread (or one of the other multitude on windshields - whenever someone new tries things it starts an entirely new windshield thread - NTTAWWT..) I mentioned I'm finally pretty happy with what I have at the moment. Since I've been unhappy with all the other solutions I have tried over the past 32,000 miles, this to me is perhaps a breakthrough.

I'll reiterate what I did: I moved the bottom edge of (1) a 16" Cee-Bailey shield, then (2) a 20" Cee-Bailey shield out about 1.5" from where they started out with the stock BMW touring shield mount. This not only opened up a large air passage under the leading lower edge of the shield (the "CalSci effect" of breaking vacuum behind the shield so the vacuum doesn't cause air to collapse into it behind the shield), it also increased the rake of the shield.

Experiment for'ya: hold your hand straight out like you're a BoyScout saluting (palm forward, fingers up) doing 60MPH. Do it off to the side so your shield isn't blocking any air. Then turn your hand to a 45 degree angle to the wind. Note what happens: (1) Much less effort required to hold the hand out (2) It becomes smoother. You're seeing the effect that a sharp edge pushing through the air has - and how it creates vortexes off the trailing edge. At an angle - the air moves along the surface of your hand instead of being fully displaced by your hand. Less effort is therefore required to hold your hand there.

Anyway - long explaination.. right now (subject to change at most any moment) think that what bothers me (head turbulence) is being caused by air collapsing behind the upper edge of a shield. The effect is made much less noticeable if (1) you break the vacuum behind the shield (2) you angle the shield more so the air doesn't tend to make vortexes.

Using my hand - feeling for where the turbulence is - with the current mount/shield it appears to be about 6" above my head. Might be hell for a pillion, but for me it works great. Would be bad for someone 6" taller in the saddle than I am. I haven't tried the 20" Cee-Bailey yet - but - it's almost cold enough to, so I might give that a try tonight.

YMMV - but see where what's bothering you originates from.. noise I can deal with (I wear earplugs all the time anyway). Turbulence slows me down.

[GOTJ]

Don,

On your next ride, take your left hand and cover up the right wind tunnel. That effectively covers both with your elbow over the left tunnel. I would be very surprised if you didn't get a significant reduction in helmet noise. At least this a free and easy experiment compared to what you have been up to.

[BobbyLeBout]

I hope that the rolled up stuff costs more than a Parabellum Scout Fairing so I feel better about the purchase. After installing the new fairing and highest windshield possible a short test ride told me I still had major noise in the helmet.
So I did what any other idiod would do, I didn't ride all summer. That was mostly because of business demands but I was discouraged by the wnd noise. This wind noise was coming from over the windshield not from below. Last night I took three inches off the Parabellum windshield. I had a dead battery so no test ride last night. Will ride to work today and saw off more of the shield tonight if needed. I believe that the Parabellum will be shortened to 6 to 10 inches and the Rt shield will be mounted behind it. This should cut off the southern air (because of fairing) and because the RT shield is adjustable it should cut out the NNE N and NNW air also.
How much will you sell me a roll of that stuff for. I know you are thinking you can get hundreds for it. Thanks