I use my bike for commuting as much as I can get away with it.
I think everybody pretty much touched all the financial aspects of the ownership, but here are few little items I have not read:
-- I realize you will not be getting rid of your car, but you may get a break on your insurance if you are not driving it as much (I do).
-- When it is all said and done (including depreciation value) bike is cheaper to commute with than it is with a car. I noticed you put the bike commuting values, but you didn’t put down how much you would spend on a car. Yes, since you are not getting rid of your car, you will still spend “some” but “not” all of that money on the car because you are using it less which may ofset your bike costs a little more.
And the biggest reason I use my bike for commute is: TIME
If you are living in a high traffic area like me (my area is ranked second worst in the country, yeah!!!

), having a bike may save you a lot of time from your commuting and “time” is my most expensive line item for commuting. On the average, my one way travel time is 20 minutes from “door” to “door” between my house and work on my bike because I get the take advantage of HOV routes. Same trip is 45 minutes on my car, and 1 hour 15 minutes if I take public transportation. Most people do not consider this, but it is very important to me.