Looking at getting a windshield for a 2009 sportster. I can get a pretty good deal on a 17 inch one. I'm 6 foot 1 so i don't know if a 17 inch one is big enough

 

I'm 6'2". A 17 was not tall enough for me. I had to take the attachment hardware to a plexiglass co and have one made to fit me. Top of windshield comes to just below my nose and is just perfect

 

Top of windshield should be lined up between your upper lip and nose. Here is a video of how to measure.