[CeeBeeArr]

I decided to try raising the quiet spot behind the windscreen with a piece of plastic sheet and it is working nicely.

I drilled 4 1/8" holes in the ears of the stock windscreen. I then used snips to shape the plastic so that, when it was arched to be flat on the ears, it reached the ends of the screen.

I then held it in place while I drilled and attached one top corner of the plastic. I then arched, drilled and attached the other top corner. Finally, I adjusted the angle, drilled and attached the remaining straps. I used tie wraps which seem to work fine and don't put stress into the stock windscreen. It needs some cleanup but I was excited to try it out. This all took about 15 minutes. I think the next one will be an 1" taller and I will cleanup the edges better.

http://www.cbr250.net/forum/attachment.php?attachmentid=430&stc=1&d=1312667851

http://www.cbr250.net/forum/attachment.php?attachmentid=431&stc=1&d=1312667851

http://www.cbr250.net/forum/attachment.php?attachmentid=432&stc=1&d=1312667851

http://www.cbr250.net/forum/attachment.php?attachmentid=433&stc=1&d=1312667851

This will do me until something 'official' comes along. Maybe longer...

 

[CeeBeeArr]

Thanks for the feedback Sendler. One of the reasons I want to improve things is that I would like to get closer to your mileage achievements but cannot stay that scrunched up. So I am hoping there is a solution that lets me ride more aerodynamically and be comfortable too.

I will be making a taller one to see how that helps but this simple thing has moved the quiet zone up about 3". Very easy to hear the engine and I can actually open my visor in the bubble with little increase in noise so I am very hopeful.

It is very easy to take off and the only changes to the bike are the small holes which are pretty discrete.

 

[CeeBeeArr]

I made a taller version (Prototype 2) and made a greater effort at quality; used a template instead of free hand and better cutters. I then went on a 200+km ride managing to actually hit 150km/h at one point (whee...). The results were:

1 - It didn't fly off the bike (I was impressed!).
2 - It made a big difference (I was pleased).
3 - There is a limit to how tall it can be at that angle (I had heard that bigger wasn't necessarily better. Maybe there's something to that...).
4 - The air gap doesn't seem to make a difference at all IMO (maybe something about laminar flow).

As far as I can tell, the quiet spot starts when my eyes are about 2" below the windscreen. On the stock windscreen that is pretty darn low and I would have to get my eyes moved and a new helmet. Adding 3" to the windscreen adds 3" to the quiet spot. But if it gets too tall at that windscreen angle, you start hitting the top edge with your helmet.

Prototype 1 never saw the highway. Prototype 2 measures 6 1/2" extension at the center of the stock screen with a mild tilt up (5 degrees at a guess) to help clear my helmet.

So, the next test is to duplicate the curve of upper lip of the stock windscreen so the helmet can fit into it better. I would expect the extension at the center to be about 4 1/2' - 5". A bit of cleverness can make the lower edge of the extension match the stock screen if it is angled.

That said though, I was doing 110+kph and was able to open my visor 1/2 way behind that thing and there was minimal turbulence and the clear sound of the engine sounding as perfect as an engine can sound.

Today, I took it off to run an errand and felt the exposure to the air again so I think the thing is worthwhile. I agree that the fastening system needs to be better. I'm not too keen on nuts and bolts as they could crack the plastic. I can live with the extension cracking but not the stock screen. I am imagining some sort of plastic rivet like thing but don't know if they exist.

As to the air gap, I am not convinced it is a problem but plan to test with some sort of foam gasket first. Using silicone is a way to go but I would prefer a solution that is removable as much as possible.

But there is a lot of fun in trying to solve a problem nicely and I expect to enjoy it whatever happens; including abandoning it for something better. It's just an idea after all.

 

[CeeBeeArr]

I am taking the next version out for a day of highway riding tomorrow. This is prototype 2 with the center lowered about 1 1/2" to match the stock shape. There will be the opportunity to try it with the gap open and blocked so I will report back.

If that seems good, I will do the final and if there is interest, I can put the shape up as a pdf file for others to play with.

 

[CeeBeeArr]

I forgot, they attached with adhesive backed velcro buttons. You set them so when you put the lip on your windshield you flex it to more of an arc. the velcro worked good.

This sounds like a better idea than holes and (wait for it.....) tie wraps.

Only slightly concerned about the potential for velcro to block vision. Might be a bit annoying but unlikely to be dangerous. Certainly more adjustable.

Thanks for the info.

 

[CeeBeeArr]

Hello, I am new to this forum and as we are planning a long distance trip in the near future we are very interested by the windshield ;-) as the beginning of our trip will be on motorway for a few hundred kms/miles....
What height would you recommend as best?
Thanks and regards to all from rainy Belgium!!

I think the limit is about 11.5cm to 13.5cm (4 1/2" to 5") extension of the stock screen at the middle. Longer than this and the extension can bump the helmet due to the angle. There is a limit to how much you can change the angle of the extension in relation to the stock screen.

 

[CeeBeeArr]

OMG ... you using cable ties ...

It is a work in progress. I am spending the effort on the design shape. Cable ties are cheap, adequate, adjustable and require no special tools to use. Everything you need in a temporary restraining device.

 

[CeeBeeArr]

That looks very nicely done. I noticed in tests that my design didn't work as well in cross winds so I am curious how the wider one does. What devices are you using to fasten it to the stock screen?