Just want to say thanks for all the info you guys gave on the madstad windshield. Mine arrived today and after the install I took it for a test ride. I'm very satisfied with the purchase it has made the f3 so much more comfortable to ride. I'm 5'11 and I got the 20 inch after the ride I kinda wished I had ordered the 18 inch just for visibility over the top of the shield, so when I got back I took it apart and redrilled the base plate and lowered the shield 2 inches now I would say it's perfect.
At 5'7", I had the 20" and loved it. But, I traded it for an 18" - which I also love. The only difference I have noticed ( besides having more adjustment options ) is that the 18" does let more air in from the bottom ( 2 more inches, to be exact ). I am fine with that, but when you get your Canadian Fall, Winter, Spring a little less breeze will probably be appreciated.