The fans do help but they are not a cure. If you are huffing and puffing and sweating a lot your goggles will fog. I agree with what the above posters are saying about getting in shape and dressing the absolute minimum. I usually wear a base layer and shell only but keep a micro fleece vest and beanie handy. One of the best things I bought last year was an RSI under hood goggle bag. If my googles get too wet I pull the warm pair out of the RSI bag and put the wet pair in. Nothing like a warm pair of goggles always ready to wear. The other thing I like is those removable goggle strap thingies( can't think of the name) that have a Velcro tab on your helmet so your goggles just hang off your helmet when removed. All of these things made fogging an easy deal even in wet Washington. The fans make an annoying buzz that you can only hear when the engine is stopped too and the battery covers eject themselves until they are lost.