Balance
I like biking no-hands--it reminds me of how mysterious the way a bicycle works is. With my hands on the handlebars, I can succumb to the illusion that steering a bike is as linear and rational as driving a car. Let go of them, and the steering is by magic. I need to go left, and there's a little twitch of my hips, a little shift of my balance, and the bike angles off to my left. I don't understand what just happened. It makes me feel powerful and humbled all at once.
I wonder if toddlers feel this way about walking. By the time they're big enough to express such emotions, though, they're too blase to notice.