When I commuted to work by bicycle regularly back in Winnipeg, the coldest temp I rode in was -40C/F. I'm not sure what the windchill factor was. My commute was only 13.4 km round trip (so about 30 minutes each way in the winter), and as long as the roads were in decent shape, I rode.

I've walked in even colder temps both in Winnipeg and when I lived in northern Alberta.

And my coldest century is described here: http://www.machka.net/brevet/Coldest_Century.htm