At the basic level all our Forms are primarily about learning how to move, learning how to control and improve our range of motion and understanding how to use of body efficiently, at the surface level it is no more than a dance, the shape and sequence of any Form is simply a memory aid, learn the dance and we will always remember the individual moves so that we can revisit and rework them at a time of our own choosing, learning individual moves in isolation will foster the ability to come up with new pairings in new directions, help us to understand the why and not the how, help us to see the IDEA.
One aspect of the IDEA in Biu Gee is the addition of forces, this is the powerhouse, and it can be verified by basic high school physics, when two or more forces are acting upon the same body moving in the same direction these forces accumulate.
When I was first introduced to Biu Gee I was told to imagine that I was turning individual vertebrae one at a time rising up my spine, this is a very poor mind image because if we are moving our vertebrae individually we are only creating one vector and so we cannot be adding forces, it is also physically impossible this is not how the spine works so we are pretending to do something that is outside the realm of possibility, this is a slippy slope for Martial Artists.
The first flying elbow rotation in Biu Gee introduces the idea of adding forces, the waist turns independent of the rest of the body and creates force, the torso turns independent of the rest of the body and creates force, the shoulder girdle turns independent of the rest of the body and creates force, the arm rotates in the joint of the shoulder independent of the rest of the body and creates force, the body shifts its axis and creates force, in application all of these actions need to be in motion at the time of contact, but when working on the Form we can isolate them to get a better understanding of how to bring about the forces we hope to add together and a clear idea of where they came from in the previous forms.
Although there is lower body movement in Biu Gee if we look closely we see that this is Chum Kiu movement, Biu Gee sits on top of Chum Kiu, keeping this in focus allows the upper body to work independently of the lower body or to work with a different movement of the lower body, the flying elbows are equally at home with the Chum Kiu shift as they are with the pivot or even if required from a static position, it has to be this way or it will be of zero value in the unpredictable environment of a violent encounter.
To a very large extent Biu Gee is the opposite side of the coin to Chum Kiu, especially when we look at where we place our weight, Chum Kiu receives force and as such the weight is in the rear leg and the awareness sank into the lower Dantien, Biu Gee issues force so the weight is shifted to the front leg and the awareness raised to the middle Dantien, as a generalisation we could say that in Wing Chun we take everything into our tummy but send everything out through our chest.