How many of you ride centuries and other long rides during the winter in sub-freezing temps? Do you have any tips for those considering doing one?

I just rode my January century (I'm attempting a century a month again this year) yesterday and two main tips I could offer are:

1. Ride manageable loops to and from your home. What's manageable at -30C might be different from what's manageable at 0C, so you'll have to work that out.

2. Drink lots when you've arrived at your rest stop (home). When that bottle is frozen solid, you're not going to get anything out of it!