I purchased a Freewheeler two months ago (with windshield). I had a 25 mile ride home on the Maine Turnpike (70mph) and could not believe the blast of wind hitting me on both sides of my head. When I got home I removed the windshield and found that at 70mph there was no wind hitting me from the sides. WTF?
I put the trike on cruise control and felt around with my hands to find out where the wind was coming from. It appeared that the wind comes off the tank at about a 45 degree angle up and out. Without the windshield this wind passes right by each shoulder and not into the side of your head. When you add the windshield, the slipstream from each side collides with the air coming off the tank and WHAM! right into your head.
I read how some have had luck with a DK tank lift. I added one (2") and got about a 50% improvement.
As a last resort I added a couple pieces of 1/8" lexan to the windshield and to my surprise no more wind from the side. Now I can ride without needing earplugs.
My hat doesn't even want to fly off anymore. The trike now feels like my previous Super Glide with a BatWing fairing!
There's only one down-side, for the first time I can hear the Harley rocker arm ticking.