I think the real reason is that a lot of people don't like to be outside. Outside is uncomfortable, and we Americans place a very high value on comfort.

We live in climate controlled homes, work in climate controlled offices. Our cars have dual climate control systems. It's more comfortable, more convenient.Why even put in windows that open or go up and down anymore? Why?

We don't have to even leave our houses. We can work from home, play at home, worship at home, order food, movies, games, talk to friends, and have sex (so I'm told), over the internet.

When your outside you're exposed to nasty things like wind, and sunlight, and dust and dirt and bugs, and germs (quick, get out your hand sanitizer). Or snow and rain... what's that stuff called? Oh, right. Weather.

And Nature? What for? I've got all the nature I can stand on TV. If I can't mow it or spread weed killer/fertilizer on it, I'm not interested.

Cycling? No thanks. I'll sit in a gym... or at home in my home gym... and pedal a machine that imitates a bike in every way except that IT DOESN'T FRIGGIN' GO ANYWHERE 'cause I think the treadmill is too... uh... 'high impact.' I'll sit and listen to my ipod, 'exercise', and watch TV.

I've seen people in the gym riding a stationary bike eating potato chips! You can't friggin' do that!

Even camping... I see more people with pop-up trailers and RVs than tents. Sure... I love 'roughing it' as long as I can bring my kitchen, bathroom, and living room with me.

The reason more people don't bike is that biking happens outside. And there are fewer and fewer people left who love the outdoors.

$.02