Most helmets no longer have the chin curtain. With a fullface helmet, this doesn't let your air escape and causes fogging. On MX style of helmets it's not a fogging issue, but does restrict your breathing.
Most people just wear a thin balaclava under their helmet. I recommend the Klim as it is very thin with windstopper gore-tex lower area around your neck and a moisture wicking upper.
Powderbrad, your face will not freeze. As I stated earlier, you will want to put some kind of a breath guard in your helmet. This will cover your nose and cheeks. Your goggles will cover the rest. I've ridden -20 many times with no issues and felt I could go even colder. In fact my hands get cold before anything on my face.
Most people just wear a thin balaclava under their helmet. I recommend the Klim as it is very thin with windstopper gore-tex lower area around your neck and a moisture wicking upper.
Powderbrad, your face will not freeze. As I stated earlier, you will want to put some kind of a breath guard in your helmet. This will cover your nose and cheeks. Your goggles will cover the rest. I've ridden -20 many times with no issues and felt I could go even colder. In fact my hands get cold before anything on my face.