I gave my 'usual' commute distance, but I use a number of different routes and methods. My normal day is 10 miles in the car followed by 12.2 miles on the bike, and return. A 'short' bike day is 14 miles in the car and 8 miles on the bike. A long bike day is either skip the car and 20 miles each way on the bike ~ I've only done this a few times~ or alternate route back to the car which is about 17 miles on the bike.

I can also substitute transit for car, which I do in summer time (no need to get daughter to school). Then my short goes down to 1.3 miles on the bike, and ~19 miles on transit, medium goes to 10 miles on bike, 10 miles on transit and long option is aforementioned 20 miles all bike.

I use the 12 mile bike option (with or without the extended route home) about 4 of every 5 bike commutes.

And now you know way more than you wanted to :-)