good or useless ? i sure can't seem to tell the differance if it's opened or closed.

 

I consider it awesome... but it depends on what you are riding... and more specifically, which windshield.

If you're behind a stock SG 4" shield, there is no difference, because the air you get is from over the top, and not dirty air.

If you're behind a 10" shield, you should feel the difference, but not at 35mph.

If I close the vent at 70+ there is a huge difference, with either of my 10" shields or my 8" shield.

And FWIW, I have 5 shields, including a stock SG shield, an 8" Ultra Elite LRS in dark tint, a 10" Ultra LRS in dark tint, a 10" Ultra WIDE LRS in dark tint, and the stock clear 10"

 

more or less air with it closed or open ?

 

Stock '14 Ultra Limited. I've opened and closed mine at varying speeds and varying conditions. None produce an OMG reaction from me, though I "think" I feel a tiny difference [but maybe that's even in my head].

 

I've not ridden a Street Glide without a vent - but my SG that has the vent, I can't really tell the difference between open and closed - though I do tend to ride most of the time with it open..

 

As I stated above, you won't notice the vent with a stock SG configuration.



You still get air, but it is clean air, not turbulent.

 

stock windshield on 2014 limited. i never noticed buffeting on 5 older baggers and don't notice it now . i don't find a noticeable different with vent open or closed

 

It might just be me but seems MoCo lowered the batwing. On my 05 with the 10" or the 5" shield i didnt notice any buffeting but on my 16 it has a lot of buffeting. I just got the wings and a lrs 7" shield i will try that as soon as my shield arrives

 

What SafetyMan says is absolutely true. Taller windshield there is a noticable difference.

I wear prescription glasses, at 50 mph and up with vent closed, my glasses shake all over. Vent open, no movement. I keep mine open, unless I'm hiding behind the shield when raining hard

 

I keep mine open most of the time , @ interstate speeds with vent closed I get a little buffeting not bad. When open clears up. I like the vent and imho I believe it's a great addition to the batwing.