Body steering is a skill less well-understood and definitely not as easily grasped, but it is also something we have instinctively learned and can be just as valuable a technique. As I mentioned in my blog from last week, body steering may not be as effective as countersteering, but using both together gives the best result.
How do you use your body to steer? To have any effect at all, you must move your body in relation to the motorcycle. Tony Foale, in his book "Motorcycle Handling and Chassis Design: The Art and Science," outlines the physics and complex interactions involved; essentially, you must move your body in relation to the motorcycle and use that inertia to move the motorcycle and initiate a turn. The actions are just as non-intuitive as countersteering, but in the same manner that we learned to use countersteering by riding a bicycle, we know instinctively how to body steer.
There are many ways we use our bodies to move objects in ways at least somewhat analogous to body steering: rocking chairs and swings are good examples, and there is the example I used last week of the wagon. If you were to sit in a wagon and not touch the ground, you can push and pull on parts of the wagon all you want, but if your body doesn't move neither will the wagon - just as you can push on your bike's footpegs or tank for all you are worth and nothing will happen if your body doesn't move. Try it for yourself, in a rocking chair, a wagon, or on your bike; if you don't move, there is always a part of your body pushing in the opposite direction to balance the forces, so no motion can happen.
We can shuffle the wagon along, make rocking chairs rock and swings swing by moving our bodies back and forth at different speeds and accelerations, so that the resultant inertia starts the motion. The same movements must happen on your bike to move it from side to side; once you have started the motion using the inertia of your body, gyroscopic, tire and gravitational (from the changed centre of gravity) forces continue the action, much as they do when you countersteer.
While this analogy does show that body steering works, it also shows just how much less effective it is than countersteering. Your body has a significant mass compared to a swing or chair, but much less compared to a motorcycle, with correspondingly less relative inertia.
We know that body steering works; you can steer your motorcycle or bicycle with no hands. One aspect to consider when comparing the relative effectiveness of body steering and countersteering is that countersteering is limited by how much front traction is available. You can literally steer the front tire out from under the motorcycle. In a low-traction situation, such as rain, dirt or ice, body steering is proportionately more effective.
Almost every racer and riding school instructor that I have spoken to on the subject says that body steering is an important and useful tool. Even if using your body lets you steer just five percent quicker, or even one percent quicker, than by using countersteering alone, it's a skill worth learning and using if you are trying to turn your motorcycle as quickly as you can.