[MENTION=21724]cyccommute[/MENTION], thanks for that constructive response! : thumb:
To clarify, the rides I refer to were long rides (100+ miles), not touring, so certainly a bit off topic. And they weren't particularly cold, starting in the high twenties, reaching the mid thirties, ending a little below freezing. I had increased my shoe size as you suggest, perhaps not enough. I had adequate insulation on top, obviously not enough below. That was my point.
I don't mean to imply my body heat was getting transmitted to the ground, but rather to the air. Metal transmits heat well, and quickly moving air takes it away.
The heat loss I'm talking about took many hours. I was plenty warm over my whole body, with the exception of thumbs, fingers, and feet. I conclude that my body heat was leaving those areas faster than it was reaching them. And it was leaving them and into the air, both directly and from the bike.
well, I'll be the first to say that 160km + rides in any temp is quite an achievement, let alone in temps below 0c. Like cross country skiing in cold temps, doing a physical activity as long as a 100 miler is always going to be a challenge in those temps dealing with sweating, cool down at pauses, accumulation of sweat over time and how it can chill you.
What you've done I wouldnt be up to, like I said, quite a challenging thing to do.