Choosing a Windshield
All Fast Aire Windshields are measured as follows
From the Top of the Fairing edge, right above the center screw ... To the Top of Windshield, in the center. That is the measurement. The material that is below the Fairing and not seen, is not included in this measurement. So if you buy a 8 inch windshield, it will be 8 inches above the Fairing.
What size should you buy ? This is important because " One Size Does Not Fit All "
Many things can affect what windshield size is best for the rider .. Rider height, seating position, low seat, riding two up, etc...
In general, most riders want to look over the windshield by about 2 inches but your choice may differ.
It's OK to look thru the shield or to look over it.
But, you must decide for yourself what is the right size for you. It's YOUR choice
Here are a few suggestions to help you decide
If you have the stock 12 inch clear shield:
Place a small piece of masking tape inside the windshield near the center.
Go for a ride and while riding, adjust the tape up or down to where you want the top of the windshield.
When you get home, get a ruler and measure the distance from the top Fairing edge to the tape.
This can also be done while sitting on the bike in the garage.
If your bike already has a short windshield, like the FLHX StreetGlide
Tape a ruler to the windshield or have a friend hold it ... sit on the bike and look forward.
Try sighting to a point about 30 feet ahead and find a number that looks right.
If inside a garage, most are about 20 ft long. Place your front wheel at the opening.
Mark the far wall 5 ft above the floor and use that mark as a sighting point.
That number will be close to where your new windshield should be.
Remember the number on the ruler and purchase the size that fits.
Airflow from the Fairing and Windshield
Rule #1 ... It is a motorcycle. No matter how big the windshield, some air will escape and find you !
Aerodynamics is the key word to controlling airflow.
HD's Fairing design has poor aerodynamics, the design is basically unchanged in 20 yrs.
In addition, the front wheel acts like a rudder and splits the lower airflow to each side of the bike.
There is alot of air that flows under the Fairing then upward towards the tank. This airflow is what cools the motor. Some of the air from under the Fairing will flow upwards and hit the rider in the chest or sneak up under your glasses. The smaller Fairing Wings help some here.
The majority of the upper airflow from a HD Fairing is controlled by the Fairing shape...the windshield just continues it upward. This is why a Glide series with a 4 inch shield will make you feel like you're getting more air than a RoadKing with no windshield.
The shorter the windshield, the more air will "spill over" the top and hit the rider.
The taller the windshield, the less amount of wind will hit the rider.
Motorcycle speed will change the airflow dynamics ... the slower or faster you go, the airflow changes accordingly.
If you want as little airflow as possible, then pick the tallest windshield you can live with.
If you want NO wind at all and prefer an airless enviroment... buy a full faced helmet and a Goldwing with a BIG shield !
It's Ok to laugh