ElectricMotorcycleForum.com
Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: scorpion32 on February 17, 2017, 08:05:05 PM
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Hi all,
yesterday i was back on my trip home. The last distance is a 15km ride on the Autobahn / Highway.
This is the time when i push the DSR to the limit and drive faster than usual. The dash reads 160 km/h. 8)
I always try to expect the unexpected if driving so fast:
- other cars moving in my way without using turn signal
- dirt or gravel on the street
- icy surfaces
- cars that might overtake from the wrong side of the road (in germany we have law that you only can overtake on the left side)
But then something happened i was not expecting.....my windshield just flipped over down to the charge tank. It was still connected, but i guess the wind driving pressure was too much for it. Suddenly i had all the wind on my chest and i was really surprised by the amount of wind at that speed. It takes 1-2 seconds until i realized what just had happened. During this time period i guess i was completely distracted from the traffic situation in front of me.
Lucky me i was not in between a lane shift or similar. Then this could really ruin my day. :(
The windshield came initially preinstalled with the DSR Anniversary Edition, so i never checked how tight it was connected. I will now re-check every single screw on that bike.
Why i post this message? Well, of course it´s impossible to expect the unexpected, but now as you are aware of what might happen to the windshield, probably this situation is more "expected" for you if you might get in the same situation.
Hopefully you never have this experience. And probably you should check if your windshield is still properly attached from time to time.
BR
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Murphy's Law: If something is fastened with fasteners, they will come loose. But thanks for posting, a good reminder for everyone to go thru the bike every once in a while and check tightness
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I've found that the MRA screens that Zero sells have stalks that are too low to mount around the center of pressure (CP) for the windshield, which is why this can happen.
One thing you can do is acquire a longer set of MRA stalks that go around the handlebars (they all match this mount) and change the angle of the mount to balance the windscreen forces better.
You can also try to brace the windscreen at a third point (or second pair of points) near the headlamp. A little metal bracket from the headlamp mount bolts up to the screen with a little clip or such might do the trick.
NOTE: If you drill through the windscreen to make a mount point, use drill bits meant for plastic so they won't catch and crack the plastic.
PS of course this'll be on the wiki...
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Wiki entry: http://zeromanual.com/index.php/Advanced_Modifications#Custom_Windscreen_Mount (http://zeromanual.com/index.php/Advanced_Modifications#Custom_Windscreen_Mount)
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Hi all,
yesterday i was back on my trip home. The last distance is a 15km ride on the Autobahn / Highway.
This is the time when i push the DSR to the limit and drive faster than usual. The dash reads 160 km/h. 8)
I came across this page a few weeks ago: https://calsci.com/ , emailed about the windshield
I currently have Zero touring screen) and asked if they had anything better (more shielding,
hopefully improved aerodynamics)
Excerpts from the company's reply:
"We have made a windshield for your bike and would be able to make another, however the mounting system that you have is not strong enough to hold a large shield without tipping backwards. I wouldn't be surprised if you have this issue already with your other windshield."
"Another option is a universal handlebar mount windshield that we are in the process of developing. "
Nice!
I think BrianTRice (or others) may have commented on this company previously ...
BTW, what sort of range do you get as 160?
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Hi all,
yesterday i was back on my trip home. The last distance is a 15km ride on the Autobahn / Highway.
This is the time when i push the DSR to the limit and drive faster than usual. The dash reads 160 km/h. 8)
I came across this page a few weeks ago: https://calsci.com/ , emailed about the windshield
I currently have Zero touring screen) and asked if they had anything better (more shielding,
hopefully improved aerodynamics)
Excerpts from the company's reply:
"We have made a windshield for your bike and would be able to make another, however the mounting system that you have is not strong enough to hold a large shield without tipping backwards. I wouldn't be surprised if you have this issue already with your other windshield."
"Another option is a universal handlebar mount windshield that we are in the process of developing. "
Nice!
I think BrianTRice (or others) may have commented on this company previously ...
I'm glad to hear they're working on a generic mount. I got in touch with them as well but ultimately with the winter weather and extreme schedule business, it was easier for me to buy a used CalSci windscreen on EBay, and mount it to my MRA stalks for use with my dustbin fairing.
The main thing is to estimate where the center of pressure is for the surface (kind of the center of the area so it matters where the screen is wider) and place the mounts directly behind that. So, I have those 11" MRA stalks from the handlebars to the screen (meant for a BMW R1200RT, which has a big fairing, so my mount was above the original holes) and it works pretty darn well and doesn't tilt into the wind at 85mph.
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My cheap Chinese shield hasn't moved a bit, with repeated rides on the interstate at 85 mph with Chinook winds.
2015 FX ZF6.5 👹 DoD #2160,6
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I've found that the MRA screens that Zero sells have stalks that are too low to mount around the center of pressure (CP) for the windshield, which is why this can happen.
One thing you can do is acquire a longer set of MRA stalks that go around the handlebars (they all match this mount) and change the angle of the mount to balance the windscreen forces better.
You can also try to brace the windscreen at a third point (or second pair of points) near the headlamp. A little metal bracket from the headlamp mount bolts up to the screen with a little clip or such might do the trick.
NOTE: If you drill through the windscreen to make a mount point, use drill bits meant for plastic so they won't catch and crack the plastic.
PS of course this'll be on the wiki...
So, I am another user affected by the flipping of the MRA touring windscreen. The thing is that my windscreen kept flipping at 130/140+ Km/h speeds, mainly when combined with windy days. So I kept tightening the screws that fixes the screen in its position, until I overtightened and broke the plastic holding the joints. Additionaly, I no longer can get the stalks into their aluminium holder, the holes are closed enought so that the stalks no longer fit in there :'(
I am now in the process of deciding what to do: buy a replacement from MRA (new stalks, joints and the aluminium pieces holding all to the hadlebar, buy the longer set you refer to fixed to the handlebar or buy a new windshield.
If I opt for the handlebar mounted set, i wonder how would that change the center of presure?. By positioning the stalks as parallel to the ground as possible? Wouldn´t that set it so low that it would interfere with the front light?
By the way, as an alternative, I was thinking about two Puig windscreens, the "Bat" (more protection), and the "Rafale" (I think it looks cool in a DS/S). Do anybody have any real experience with Puig attachments? since they look nearly identical to the MRA attachments, including the joints tightening mechanism...
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My Zero-brand MRA windshield tilts back when traveling over 50 mph. Tightening all of the screws helps some but doesn't really solve the problem. So my solution is to fasten some Velcro material to the bottom edge of the windshield and to the top edge of the headlight housing. That seems to help hold the windshield in place, while still allowing it to be removed for cleaning. Of course, that will result in fixing the angle of the windshield.
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The center or pressure for the windscreen is a property of the windscreen shape and its position in the airflow round the bike. So you can’t readily move it.
To eliminate the pivot problem, the stalks must join the windscreen at a higher point, so that the pressure of the airflow is either closer to, at, or below the pivot axis of the windscreen against the stalks.
MRA windscreens are made of PCA if I remember correctly, less brittle than acrylic but still difficult to drill correctly. I bought a set of drill bits rated for acrylic and made two 6mm holes higher on the windscreen. So the mounts used the original upper holes and then this new set of higher holes. I forget the distance between holes needed for the MRA stalk mount brackets but it can be derived with a metric rule.
I didn’t do this for long on the MRA windscreens; I soon bought a larger windscreen which I then customized this way to make a 4-point mount with sliding brackets, so I could start my process of aerodynamic optimization study.
But I used the longest MRA stalks available for the upper mount for a long time, and in various cases just made sure they wouldn’t pivot, and that the lower end would stand off from the headlamp by a good 2-3†for the best laminar flow above and below the windscreen to minimize turbulence around my head and body.
And now I don’t do any of this, since the Hollywood Electrics fairing places the windscreen and headlamp into a proper faired cockpit.
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I forgot to mention a way to approximate the location of the center or pressure for a windscreen: use the geometric centroid of the outline in 2d. A trapezoid is one way to simplify the shape to get an answer with algebra, but the intuition is below:
Basically for a windscreen that’s wider at the top than the bottom, it’ll be at least halfway up from the bottom of the screen, and might be up to ⅔ way up the length of the screen. That’s where the center of wind pressure can be thought of as pushing on the windscreen.
Imagine all of the wind’s force applying to a single point there, and you’ll grasp why you have to do something like moving the mount upward or pull on the bottom of the screen.
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Yikes, sounds very unnerving at any speed. You weren't clear on whether the plastic bent, the braces bent, or the screws went missing.
Once I was on my Super Tenere on a dirt road in the middle of nowhere and thought I saw the windshield move funny. I stopped and found that all four sets of thumbscrews and washers and mounting bolts were completely missing. The windshield was just resting lightly on the mounting brackets! I duct taped it back on to finish the adventure. Later I used wing nuts and tightened them with vice grips. Not easily adjustable anymore, but who ever needs to adjust it anyway?
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Yikes, sounds very unnerving at any speed. You weren't clear on whether the plastic bent, the braces bent, or the screws went missing.
Once I was on my Super Tenere on a dirt road in the middle of nowhere and thought I saw the windshield move funny. I stopped and found that all four sets of thumbscrews and washers and mounting bolts were completely missing. The windshield was just resting lightly on the mounting brackets! I duct taped it back on to finish the adventure. Later I used wing nuts and tightened them with vice grips. Not easily adjustable anymore, but who ever needs to adjust it anyway?
It was me the one who broke the plastic receptacle where the ball joint is inserted. Since the windshield moved, I kept tightening the screws until that plastic piece failed. Nothing broke or was bent by the wind but by my own hand...