Newbie question. Today was my first ride in heavy fog/drizzle. My face plate quickly became impossible to see through between the mist and fogging. When I opened it up, my glasses quickly suffered the same fate. I kept wiping them off every few blocks. It was pretty scary. What's there to do other than not ride in these conditions?
Don't ride like this....
BTW-next time the shield starts to fog up .... just give it a little spit and wipe

like a scuba diver does to his mask before diving
best anti-fog ... best part , is free
other tips:
don't open the shield all the way , only crack if need
shake head at high speed for rain drops to disperse
open rear helmet vent , close front
keep your body in a tuck position (unless you're a anti-tucker)
keep a zip-lock bag handy for cellphones , wallet , ect..
keep your route in mind , try not to make too many unnecessary stops
be extra alert , and give yourself extra space
try have fun , is like a land jet-ski
