Studded bike tires, along with LED lights, have transformed winter biking in Anchorage in the last ten years. But while we think of ourselves as state of the art in these things, I discovered this studded tire in Michael Embacher's Cyclepedia that is listed as 1966!
UPDATE 4:25pm: Sorry, I was in a hurry and didn't get this part up.
Another part of winter biking is being in a community where bike trails are cleared of snow. Some Anchorage bike trails are cleared fairly quickly by small snow plows, though there is the problem of street plows then throwing street snow back into the bike paths.
For another view on this, here's a post from BicyleDutch about bike trail clearing in Holland:
When I mentioned the city of ’s-Hertogenbosch had forgotten to clear one new cycle route of snow in my post two weeks ago, the city quickly responded and the route was gritted right away. For the future the route is now included in the ‘to be cleared main cycle routes’. That was possible because the ‘city’ is of course a number of people working hard. One person read my post and contacted another person who is in charge of planning the actual gritting. A few days later I was contacted, and asked if I’d like to have a look at how ’s-Hertogenbosch works to keep its city streets safe, by clearing the main routes for motorised traffic and those for cyclists of snow and ice. Well, yes of course I was interested!There's pictures and more of the story if you go to the site.