The woman's weight must be on the ball of the foot so that she can pivot as if on a fixed pin. But she does not pivot her whole body. She only pivots her lower body from the waist down. The waist is like the swivel that joins the upper body and the lower body. Because her upper body is connected to the man who is in front of her, she has to rotate her lower body, letting it face a different direction to enable her movement around him. This is known as “dissociation”.
An experienced woman knows that a small twist of her torso by the man indicates, and must result in a big rotation of her lower body. The man leads her by turning her torso slightly to the direction that he wants her to go. On receiving the signal, she needs to swivel her hips until they are perpendicular to her upper body. In this twisted position she is able to walk on the side of the man while her torso is connected to his. The technique suits the flexible body of the woman and highlights her femininity, as she alternately turns her hips side to side while her chest is constantly facing the man.
A typical figure using dissociation is the ocho, in which the man leads her to draw an S on the floor with one foot, and then draw another S on the floor with the other foot. The two S’s are overlapped in the opposite directions so they look like the figure 8. To dance the ocho, she has to swivel her hips to one side and make a forward step with one leg, then swivel her hips to the other side and make a forward step with the other leg, and then swivel her hips back to face the man. A similar figure using this technique is the back ocho, in which she dances the ocho backwards. She first swivels her hips and steps backwards to one side of him with one leg, then swivels her hips and steps backwards to the other side of him with the other leg. A third example using this technique is the molinete, which is a combination of a front ocho, a side step, a back ocho, a side step in a circular motion. In all three examples the woman keeps her chest connected to the man and rotates her hips from one side to the other side alternately.
The rolling of the torso is caused by the rotation of the hips. To create the gear effect, the woman has to swivel her hips fully until her torso rolls along. She needs to make the rolling void of abruptness and bumpiness so it feels smooth, musical and comfortable, which is not easy to do and needs a lot of practice to master. A beginner who can't do dissociation often crosses her leg instead. Consequently, her torso remains square and does not trundle. Tango is a dance in which both partners pleasure each other with their bodies. An experienced woman knows how to use her body to seduce the man, just like an experienced man knows how to display the feminine beauty of the woman. (See Revealing her Beauty in Tango.) Gear effect increases the sensual pleasure of the dance - a feature of close-embrace tango that is missing in the open-embrace style. It is one of the things that make the two styles fundamentally different.