Below 15F what kind of condensation do you get on the inside? I've been wearing the nosepiece from a half-mask respirator, but without the filters, and while it shields me from the windchill and pre-warms the air slightly, there is a huge amount of condensation during my hour long commute.

With the device you mention, from where does it draw air? Does it go all around you neck like a gaiter and you draw the air in via your outer shell or is the back open around the neck and you draw in and exhaust that way? Or is the device perforated somewhere?

By this I assume you mean they succumbed to hypothermia and dropped into a coma and died.

Some people get asthmatic in cold weather (like myself). If this was the case, the OP would probably already know this. You can probably beat this with a drag on an inhaler before heavy exercising. In my case, OTC Primatene Mist does the trick. Sometimes I have to take a second hit along the way so I keep it in my jacket.

Some people have coughing fits afterward in cold weather. I get this early in the season, but I'm conditioned now so I don't experience it anymore.

Your nasal cavity is directly adjacent to your brain. So maybe you want to do a little of both to keep from shocking either system.

I ride in all temps. however don't enjoy the cold weather. I have not herd of a riding temperature that could be harmful. I think it amounts to comfort, experience, gear, etc..

I rode to work today, 5 miles at -15F. I wear a neoprene face mask but cut out the mouth hole or I get way to much moisture build up. I have been riding this way for the last three years and I have had discomfort but not lasting bad effects from the the cold air. As many have said, life goes on year round in the north and we survive. I have never heard of any one dying from breathing the cold air. It is exposure that is the danger.

I'm having good luck with wool bavaclavas. In colder temps (10F down to about 0F) one with a double layer of fabric is good. The wool doesn't stink up the way synthetics do. If you keep it over your nose it creates a nice pocket of warm air right around your face. I had a beard for a while earlier this winter and found that it got too warm in temps from about 15F up. No issues with coughing/chest pain/congestion. I can't speak to the really extreme temps though as I haven't done any riding in them, Southern New England just doesn't see temps much lower than the teens very often at all.

who would even think about riding in sub zero temps w/out a mouth covering?

it was -8 F this morning and i rode 12 miles to work fairly comfortably by layering right and covering my face.

Most people living north of 60 N.

Even with a history of cold induced asthma symtoms I've commuted all winter, coldest day +1F. Thanks meds.

How about, ride slower? I use a face mask which restricts breathing, especially when wet. Which basically means I need to ride slower, also in the winter I tend to ride slow enough to barley sweat. I try not to sweat.

All I use on top of a t-shirt is a wind breaker, and I still get sweaty.

Drawing in cold air through your nose sends the exact same kind of shock to your brain as exposing any other body parts to cold. The fact it happens in an area "directly adjacent" to your brain has no added thrill to it. It's a matter of getting used to.

Somehow people manage to breath in -50C regularly, even without sophisticated air-preheating systems.

--J