Mostly tight time windows, such as an early morning meeting that starts just a short time after I can get my kids delivered to school or on the bus. Dinner dates with my wife can also be an issue since I don't want to show up at home all sweaty at the same time the babysitter arrives.

Other days I have errand appointments that would be difficult or very time consuming to accomplish without the car, such as taking a kid to the dentist and then to school.

I'll admit that rainy mornings deter me from cycling, but they don't happen as often as other issues.