I have two approaches that both work. First is to wear a Full Face helmet with a Fog City or similar (Shoei pin-lok etc) inner shield on your outer shield. I have ridden in the Keys with this in hour long downpour and no fogging and clear vision. Other is what I used before starting to wear Full Face helmet, Oakley or similar SNOW ski goggles, the Snow Grade has twin lens, This works the same as the Fog City on a Full Face. I tried everything and these are the only two remedies I can find that work, Road 480 miles from Atlanta in a constant rain a few years ago with the Snow goggles and had good vision. I do tape the lens off and spray the breathing outer foam with Scotchgard protectant but then I spray everything with Scotchgard. You can get the Oakleys for a normal head or a different model for glasses wearers and also multi-colors of your choice. The Fog City inserts and also the Shoei/Nolan's all come in colors of your choice and are instantly removeable when you don't need them or want only the clear shield. The FOG CITY is permanent when you install it but works the best.