I hate the stock screen, I 6ft and not sure what size to get. I want to stop the wind from beating on me. So im not sure what to buy.
Most manufacturers have instructions on their website of how to measure for proper height. HD only makes "one size fits all", which is useless unless you happen to be the right height for their product. I would suggest some other brand. Cee Bailey, Clearview, Klockworks, Windvest, etc. There's a bunch of them out there.
Basically, here's how you measure on a RG: Get an assistant. Sit on the bike with it upright (like on a jack with the tires still touching the floor) in your normal riding position (if you slouch, sit straight up, etc), with both feet on the floorboards. Use masking tape to affix a yard stick or straight edge to the CENTER of the windshield with the bottom edge flush with the bottom of the windshield where it attaches to the fairing. Now get another straight edge and hold the end of it between your nose and your upper lip...a string or tape measure will work as well...have your assistant level the straight edge or string from that point over to the windshield where you have the ruler taped. Have your assistant mark the point at which the string or straight edge intersects the windshield centerline when LEVEL and in your NORMAL riding position. An inch makes a lot of difference, so get this right!! This mark will give you a point of reference to figure out what you need. IF you did it right, the mark should be at a place where you can see over the shield to a point about 50 feet or less on the ground in front of the bike. This gives you a measurement, in inches, of how tall the new shield needs to be from the bottom of the centerline to the top of what will be the new shield. It will likely be somewhere between 13" and 16", depending on your torso length. Could be more, could be less, depending on your height. Get off the bike. NOW, take your ruler and put the end on top of the speedometer/tachometer bezel, perpendicular to the ground, with the bars/front tire straight on . Referencing the mark you made on your shield, the 90 degree intersection of that mark and the ruler you're holding perpendicularly will be the height measurement in inches.
Each manufacturer sells their shields using one of these two measurements, or both. Remember that generally, each manufacturer's shields may be slightly different in the ANGLE of the shield. But, if you've got both of these measurement, and discuss it with their sales rep, you'll get it right. Some might measure from the center of the middle hole on the shield for the first measurement, but that is easy to account for by simply subtracting the fraction of an inch from the centerline hole to the bottom of the shield, usually + or - .5", from your first measurement. If you prefer looking through the shield, adjust accordingly (looking through the shield is not recommended by ANY safety standards). Neither do you want the top of the shield in your line of sight when looking 50' or so in front of the bike. Remember that when going up a hill or incline, the relative position of the top of the shield is going to get higher, so it is critical that you can see an object on the ground approximately 50' out when on level ground. If you wear a half helmet, or no helmet on a RG, all bets are off, but this will be really close to perfect. If you wear a FF helmet...no problem. Unless you have a death wish for riding at night, do NOT get a dark tinted windshield if measuring like this...you won't be able to see chit directly in front of you. A light tint is fine though...most make dark, light, and clear. Dark is fine for looking cool, but useless otherwise. If you want the bike to look cool with a dark shield, get one about 8" tall...it will be practically useless for wind protection, but may be OK for tooling around town or bar hopping. Get something the right height for distance riding. If you're going to err, do so on the taller side...you can always cut down plastic if you find it too tall, though it may be a little inconvenient to do so. Disclaimer: I ain't guaranteeing chit, so use this technique as a guide or reference only. Then talk to your sales rep to fine tune your selection.