...other than one's face freezing off, little details like that!
Well, Jim...that's a pretty important detail! During the few times when it is
really cold here, I ride with a balaclava like yours, but where my cheeks are exposed --
ouch! Years ago (27), I commuted regularly in 2.5°-5°F/-16° to -15°C...and then it rained (freezing rain on-contact...made little hard hobnails of frozen rain that reminded me of Ice-Nine in the Kurt Vonnegut story (
http://en.wikipedia.org/wiki/Ice-nine ). I was wearing my fingerless cycling gloves, and then went into my work-study position at Uni, where I processed parking tickets to raw keypunch cards (showing my age, aren't I?
). I...found I couldn't write anymore, and then my fingers began to hurt -- the ends looked as if someone had inserted white pearls under the skin. I went to the Uni health service for an opinion and was told I had frostbite in 8 of my 10 fingers. They're been cold-intolerant since, though I find if I wear something to break the wind -- even nitrile solvent-safe gloves -- they do pretty well.
But back to derailleurs vs. Rohloffs in the cold...I never had much trouble in cold and ice with derailleurs and made and rode my own studded tires (they made pretty yellow sparks at night if I applied the rear brake too hard and skidded on pavement -- which I did a lot, after discovering the pretty yellow sparks). The derailleur held up very well and I had no problem save the times the bike had to be parked out all day in near-zero temps and we had the freezing rains. The crust that formed looked a lot like that shown in the photo referenced above, but it also peeled off after a short time.
I think I avoided many problems by not riding in deep snow. Deep snow (whether powder or wet) tended to pack up in the mudguards and froze the tires to the mudguards and that was the end of forward progress. I finally concluded with my road bikes at the time (700C wheels), fairly tight mudguard clearances, and the sort of snow we get around here, the only way it would be very successful would be if I went without 'guards. I never did, mostly because that kind of snow and those temperatures never lasted in combination much beyond three days, and it was easier to find other solutions or ride on plowed roads and forego the unplowed bike path (especially after one sort of desperate can't-be-late pre-exam commute when the wheels packed up and I ended up carrying the bike through 6 inches of snow for 5.5mi/9km. Then home again in similar fashion. It was a long day but I did well on the exam, so it was a good one in the end.
Good to hear the Rohloff never gave you any trouble, Jim. Looking at that photo of yours, the room just chilled about 20 degrees, and I backed my chair away from the computer screen so I could rub my hands! What a terrific shot! You look very intrepid and extremely capable!
All the best,
Dan.