Roody shared an article in another thread about adults in NYC learning how to ride a bike for the first time, and this got me to thinking about the current generation of young people. I teach in a middle school in Seattle, a very bike-friendly city. Thousands of people commute to their jobs by bike pretty much every day. However, most of these people are over 30. Some college-aged or high school-aged people I know will enthusiastically ride bikes around town, but most in this age range avoid bikes like the plague (or any other form of mild hardship, for that matter), and generally view bicycles and the people who ride them with disdain.
At the middle school level, it's even less bicycle-friendly. The vast majority of the students that I teach are driven virtually everywhere by an adult. I have actually seen students who live 10 blocks from school wait for 45 minutes to get picked up by a parent in their SUV. Most of these students actually know how to ride a bike, but they, and their parents, view them as too dangerous to use as actual transport. At the end of this school year, we actually gave an award to a set of three brothers because they were the only students in the whole school who actually rode their bikes to school every day. Some students are aware enough to recognize that cars are not automatically a part of their future, and they'd rather have an iPhone than a car if push came to shove, but, in all honesty, most of my students see bicyclists as eccentric at best.
I think it's based on a lack of education about bicycling. When I was a child, way back in the 1970's, schools actually trained kids how to ride bikes in traffic. When I rode a bike in college, and again after I decided to go mostly car free, I drew on this training, and naturally took to the roads on my bike as if I were in a car. Young people now don't have that training to draw on, nor do most of their parents, so the whole bike thing just seems too dangerous or inconvenient to bother with.