Best way to prevent fogging of your helmet is to devide off your mouth/nose area from your eye area. Some helmet manufactures make inserts that cover your nose/block off the area. Otherwise, taping duct tape to your face and helmet to block off your breath works great.

Like this...

http://gridsport.net/store/catalog/h...FQiHaQodwJkATA

Or this...

Whale snot

Re: Best Helmet Anti-Fog?????
 

Lemon pledge worked for me.

Bounce dryer sheets clean lens with it. Used for years racing MX

Actually spit works, but found the new Bell DSAF(I think) shields are awesome.

Ask Robert ballou after Friday night at east bay I'll bet he now know's😊

Robert knows what doesn't work. In all fairness, when you have a very cool, damp night, nothing is full proof to hot breath on a shield.