Windshield extension | GTAMotorcycle.com

Windshield extension

J

jeff96

Well-known member
I've mocked up a windshield extension for my 2008 CBR125. I've noticed tucking dramatically increases speed / reduces need for throttle, and I was hoping a bigger windshield might give me some of that benefit. I know it's possible that this might increase buffeting (or reduce it) and it's difficult to tell without trial and error.

Can anyone see from the mockup any potential pitfalls? I was thinking 1/8" acrylic. the approximate size is 13" x 14"
 

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How much taller is it than stock? Is there any openings at the bottom to counter the vacuum created behind a large shield?
 
If I was making one I would prefer using mylar covered polycarbonate as it is shatterproof.
 
jeff96 said:
I've noticed tucking dramatically increases speed / reduces need for throttle, and I was hoping a bigger windshield might give me some of that benefit.

Can anyone see from the mockup any potential pitfalls?
Click to expand...

I could be wrong, but I think you'll be reducing one drag (air across your helmet and body) with another one - air hitting the windshield.

The latter is likely 'cleaner' and will still help (not to mention the perhaps more comfortable ride) but you are in effect replacing one drag with another so I would keep that in mind.

Is your line of sight (when sitting on the bike in riding position) still over the windshield, or through it?
 
The extension will only be about 6 inches above the existing wind shield. It's much smaller than a touring bike screen so I wasn't too worried about a vacuum behind it.

I can always laminate it with a film later once I confirm it works (or not)

Good point about creating a new drag. I'm 6'2" and my chest and shoulders are not very aerodynamic. My hope is that the drag from the extension is offset by acting as a fairing for my shoulders. Sitting upright, the screen is below my field of vision but I would be able to tuck behind it which I can't really do with the stock set up
 
Worth trying if you are just making an extension. You could also make an angled lip to deflect the airflow higher without adding as much height. The touring guys use similar attachments.
 
+1 on the Laminar Lip.

It's basically an airfoil which directs the air flow directly up without adding considerable height to the screen. If you wanted to build one yourself, try to copy the design:

flo2.gif
 
I like the laminar lip idea though it doesn't list my 125; the closest would be the 250r. I'll give the extensiona try and see what happens
 
Double check the material you're going to use, and make sure that it won't splinter into sharp edges upon an impact.
 
I took the bike out for a few hours today to try out the new extension and a sprocket swap from a 42t rear to a 44t.

It feels like I can get up to highway speed faster and the engine isn't working as hard; cruising at 100 kph with a bit of throttle to spare. (I know this sounds lame compared to most motorbike performance standards but for an engine in the small lawnmower displacement range, I think it's pretty good)

I can't say if my wind shield extension has a role in this improvement, but I suspect that it does. It feels like I'm getting some of the benefit of tucking without having to tuck. I can't tuck down as far anymore because my helmet hits the wind shield if I try to lie on the tank, but that's not something I was fond of doing anyway. When we get warmer weather, I'll try some comparisons with and without the extension.

https://drive.google.com/open?id=0B21JiKNBlYbeQjlPSzlzT090YWM
https://drive.google.com/open?id=0B21JiKNBlYbebUI0NW9iNUpzVmc
 
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