When it comes to balancing breathability and wind protection in cold weather cycling gear, particularly with face masks and headgear, the key is to find materials that wick moisture away from your skin while also providing a barrier against the wind.
For face masks, a fleece-lined neck gaiter can be a good option as it provides breathability and can be pulled up to cover the nose and mouth when needed. Some neck gaiters also have a built-in windproof layer for added protection.
As for headgear, a thermal cycling cap made of moisture-wicking material can be worn under a helmet to keep your head warm while allowing for breathability. A windproof headband or earmuffs can also be worn over the ears to protect them from the wind.
When it comes to specific materials, polyester and nylon are commonly used for their moisture-wicking properties, while windproof membranes such as Gore-Tex and eVent are often used in outer layers to provide protection against the wind.
When selecting gear for extremely cold conditions, it's important to consider factors such as humidity, wind chill, and individual rider metabolism. Humidity can make cold temperatures feel even colder, so it's important to choose gear that can handle moisture build-up. Wind chill can significantly lower the effective temperature, so windproof layers are essential. And individual rider metabolism can vary, so it's important to experiment with different layering combinations to find what works best for you.
General guidelines for dressing in layers include wearing a base layer made of moisture-wicking material, an insulating layer to trap warmth, and an outer layer that provides wind and water protection. By adjusting the number and thickness of these layers, you can easily regulate your body temperature and stay comfortable on long winter rides.
When it comes to balancing breathability and wind protection, it's like trying to have your cake and eat it too, my friend. You'll often find gear that leans heavily in one direction. 
