Originally Posted by
cyccommute
What sort of situations can ice form that don't met the conditions I laid out? You can get some weird ice forms that freeze at higher than 0°C but you won't find the conditions necessary at ambient pressures. No one has invented
"Ice-nine" yet, thankfully. Ice is going to form at around 0°C (perhaps a little lower) when the roads are wet. If the road is dry and there is no precipitation falling out of the sky, you won't have "black ice".
You are mistaken in thinking that I don't ride in ice. I ride all year long and have crashed many times on ice...see above...I have lots of experience with ice while driving as well. I've never experienced any kind of condition where the ice was "invisible" under any kind of lighting conditions. And, as you said, I can expect ice from November through March, although for Colorado, you have to extend that time frame to May, but if there is low visibility or clear skies and the roads look wet, I expect there to be ice.
Your understanding of how black ice forms is lacking... -18C / 0F is that magical point where de-icers stop working and water vapour from exhaust can condense and freeze.
It might not look wet because of the lighting or lack thereof, and there may even be a little sand to make you think things are okay and then you gently touch the brakes to find that things are smooth as glass.
For the record, my Jeep is all wheel drive with ABS and excellent winter tyres and I have 30 years of accident free driving in extreme weather conditions... this morning was a highly cautious driving experience when I left the packed and icy streets where the AWD works really well to the streets that had been cleared and had built up black ice at every intersection.