Any one of your bikes is worth more than your car.
You choose an apartment solely on the basis of whether or not it is flat enough to ride into and how close the good roads/trails are.
Your bike rack is worth more than your car.
Your legs are tan only to mid-thigh.
The first thing you ask when you regain consciousness is "How's my bike".
You actually move farther form work so your bike commute will be longer.
You mentally log every meal as "good fuel" or "bad fuel".
Your learn you have X money left over after paying bills and the first thing you do is reach for the nearest bicycling catalog.
75% of the tools you own are from Park or Campagnolo.
You dream of winning the lottery, and the first thing you think of is "how many/which bikes can that money buy?"
You can tell your significant other with a straight face that its too hot to mow the lawn then take off and ride a century.
Someone in a car asks for directions and you accidentally give them a route that includes motor vehicle barriers, or a route that bypasses all freeways/busy roads (or is very scenic etc.)
You buy a car based on whether or not a bike will fit in the trunk/back
You pull up hard on the steering wheel trying to jump your car over a pot-hole.
You know the distance of every point of interest within 20 miles of your house as well as the location of every pot-hole along the way.
You refuse to buy a couch because that patch of wall space is taken up by your bikes.
Ring a bell?