dobro
Supercharged
Your height has little to do with this!
I be 5"11" yet I sit taller than most at 6'2" or more.
Torso height is what counts.
I prefer my shields as low as possible so that they just break airflow above my eyebrows at 50+ mph.
Depending on shield angle and distance from your face, for me this is usually ay 21 -22 inches when measured from the cut above the headlight.
HTH
I mentioned my height to give some perspective for mcotter, not to imply that there is a perfect correlation between overall height and best windshield height. One could say that neck height is what counts: One might only be 5'6" tall but have a neck that is a foot long and he would probably need a higher windshield than a guy 5'11" with a 5" neck.