I won't ride my bike if it's going to be colder than......

[shootingstar]

I moved from Vancouver over 2 yrs. ago, where I did cycle year round, except maybe total of 1 month off bike with winters average at freezin' temperatures. Lowest would be -10 degrees C (14 degrees F).

Southern Alberta is drier air year round but much colder. So if I stuck to AZfiddle's rule, one wouldn't start cycling until June and end in Oct....
So if there is dry pavement with no/little ice/snow, in the winter I bike as low as -18 degrees C (-4 F) and I was doing this every day to work, grocery shopping whenever I had these conditions since this past November. (And winter 2012).

Have cycled as low as -24 C (-11 F) which is a short distance to work or shopping.

I am cycling each trip under 8 kms. when colder than -18. Then back home, same distance. I am cycling as much as possible on bike paths. Believe me, there isn't a ton of people walking on the paths. But our city has a winter policy that does keep our major bike-ped. paths ploughed and snow-free.

What makes it colder in our region of Canada...is wind chill and flat prairie only accentuates wind, cold temp.

Calgary is 2,000 metres above sea level. Vancouver of course is right ...at sea level (if you exclude the Coastal Mountains in the photos of Vancouver area). 3 mountain ranges that run north to south, separate between Vancouver and Calgary (yes there's a ton of mountains to explore or to avoid..)...it is over 1,000 km. east of Vancouver.