I run a half helmet with a snap-on face shield for the rain. When on the highway I tilt it up somewhat and use it just like a visor on a motorcross helmet. It keeps the rain away and off of my home depot saftey glasses with zero fogging issues.

 

I am sorry, but in my opinion, if u are wearing either of the above shields you are lookin a fool. Just put a helmet on for god's sake.
Take the helmet off when u are out of the weather if u want, but those things belong in a little kid's toybox or hanging off of my welder.

 

This is the one I use without a filter for hard rain. It's great for leaving packed on the bike for those rains without FF helmet.

 

My riding buddy bought one of these when while on the road and is NOT a solution. It may have helped with the pelting rain, but he still had a major fogging issue with his glasses.

 

Shaving cream will stop fogging glasses. Go home and try it on your mirror in your bath room.

 

Full face would work best to keep the rain out. I use three helmets full face, 3/4 and 1/2 depending on the weather.

 

I came accross these HJC's with built-in retractable sun shades, I believe Harley sells their re-branded model of the HJC 3/4 model:

 

Under some conditions a full face will fog up big time if it's real humid.

 

I have no experience with full-face since I'm the claustrophobic type. I ride in a Shoei RJ Air 3/4. I keep a snap on shield in my saddlebag of downpours. I have no trouble with fogging ever. However, I have rain seep between the shield and helmet where it snaps on. Therefore, my glasses can get wet inside the shield, which I find quite annoying.

I think I'm going to try a modular. It has to be better in the rain than my 3/4 with a snap-on shield.

BTW, J&P makes a little wiper blade that fastens to a finger. I find it quite handy to to a manual wipe of a face shield.

 

I use a 3/4 helmet with a shield and it works great in the rain. My glasses stay completely dry and the shield can be tipped up a little bit if it starts to fog up. When the rain stops you can flip up the shield and catch the wind on your face. My windshield blocks most of the rain and the helmet and shield block the rest.