I don't ride at night in the dark and I'm in So Calif so no snow. I ride mostly in the early mornings and I think slowing down is not the way to go. I find that many riders feel they can fix their own problems and will tell me they're ok. So now I come to a complete stop, disengage from my pedals and then ask how's it going. That way they have my complete attention and they know it. I can now dialogue and it makes a big difference.