riding skills -- no-hands ma!

Generally you don't want to time riding hands-off anytime you're riding into a headwind or if you're riding fast on flat terrain, exposing your entire torso to 16mph or more of wind will definitely slow you down!

The developing the ability to ride hands-off confidently and safely is just one more part of bike-handling skills. I routinely ride hands-off on rollers on my road bikes, doing so on my old triathlon bike was another story -- I could manage it but with my saddle set at the max-legal forward position (an effective seat-angle of nearly 78 degrees), balance was touchy and the position wasn't very comfortable.

As indicated above, this isn't something to learn or do on a bike whose frame isn't true or that doesn't fit you well. In a crosswind or headwind, trying to steer without hands can be suicidal -- gusts of wind like to catch the leading edge of your wheel and push the steering around, you can't compensate for this with balance.

How you steer a bicycle

The technical term for how 2 wheel vehicles steer is counter-steering. Fundamentally, how a bicycle steers requires that the weight of the bike & rider must move off the line of travel, into the the direction of the turn, how you actually accomplish this is to initially steer the bike in the opposite direction (hence counter-steer). As the track of the wheels moves away from the center of inertia, the bike and rider must lean the other way, the cyclist then corrects the steering back toward the direction of the turn and the interaction between steering direction and lean angle determines the sharpness of the turn.

Bikes are designed to have close to 'Neutral' steering-geometry, meaning that little rider input should be required to steer the bike. This also means that bikes that are well designed steer easily with the only input coming from the rider shifting weight.