I had previously been taught by my sensei that in front stance the weight is over the knee in front stance. This is to allow for quickly kicking mae geri (since there is no shifting of weight forward for balance).
However, this makes it difficult and slow to turn 180 degrees in kata that demand it (e.g. Heian Shodan moves 2 -> 3) because the weight has to transfer back through to the centre and then behind.
Should the weight be over the front knee in front stance? If so how much?
Fair disclosure, I do not currently practice Shotokan, but I do practice Tae Kwon Do which has a front stance and requires 180 degree turns. There may be technical differences that I am unaware of.
Drawing Into Center
Typically, when executing a 180 turn there will be a drawing in to center to recover balance. This drawing in will compensate for any forward weight in a front stance. Yes, it is clumsy, but part of forms training is learning how to execute powerful moves in awkward positions. My suggestion is that you may be missing the drawing in to center prior to the turn, or it may be a technical requirement of your teacher or your style that there be no drawing in to center.
At 17 Seconds in this video, the Shotokan practitioner appears to be demonstrating the drawing into center that I am referencing. Notice how his moving foot passes very close to his standing foot as the foot moving to the front stance passes at a straight diagonal from one front stance to the next.
Zenkutsu Dachi
Zenkutsu Dachi as with TKD front stance should be 70% weighted forward. My rule of thumb is that the knee must not go in front of the toes or behind the ankle.
Pivot on the Ball of the Foot
I re-emphasize that I am not fully aware of the weight placement in Shotokan, but in TKD, the weight is mainly in the balls of the feet most of the time. Some of the awkwardness of spins and turns can be overcome by ensuring that you are properly pivoting on the balls of the feet.
However, in the aforementioned video, the practitioner does seem to be pivoting on the ball of the foot.
It's a mistake to think of karate stances as static. They are not.
When fighting you will be in a stance for a fraction of a second. Therefore there is no correct static weight distribution.
Having said that, all stances have a purpose, and it's not always the same purpose. For example shiko/kiba dachi can be used to lower your body, e.g. applying an arm bar, as per Naihanchi/Tekki shodan, or it can be used to attack an opponent's balance.
The application for Heian Shodan movements 2->3 is to lunge forwards and grab the back of the opponent's neck (collar, hair or perhaps shoulder). The zenkutsu-dachi hits the back of his leg and breaks his balance. The following 180° rotation with gedan barai pulls the opponent over backwards.
Here is a video example of the uses of zenkutsu dachi by Eonida and shiko or kiba dachi by Machida. The Machida application is directly out of Pinan Shodan.
https://www.youtube.com/watch?v=jseW5QikD6U
Notice the stance is dynamic and retained for a fraction of a second in both cases.
I am a current student of JKA Shotokan Karate. From my notes from the last Gassuku in Honbu Dojo, we went over front stance in fine detail for most of the week. The JKA teaches more of a 60% / 40% weight distribution, with the front of the knee in line with the end of the metatarsals (specifically from one instructor, a plumb line from the knee will hang at the base of the 'V' between your big toe and second toe).
Foot positions as per the diagram posted by The Wudang Kid, though the common element I've heard in the dojo is 'One shoulder wide, 2 shoulders long'. Front foot turned slightly inwards, to make the outer edge of the foot a straight line.
The feeling of the stance should not be pushing forward at the knee, but a feeling of stability at the knee, and lowering of the hips into the stance. We are also taught to never grip the floor with the toes.
To address the turn movement 2 -> 3 in Heian Shodan, the practitioner shall shift their weight from the forward leg through the center, while keeping their supporting (back) foot flat on the floor. Turning on the heel of the foot, the transitioning foot comes through the center, in more or less a straight line, to the finishing position.
"Should the weight be over the front knee in front stance? If so how much?"
Short answer No. Please consider that the percentage of weight is the product of a few other factors. These factors will vary slightly based on body type. Just saying 70% weight over the knee is not doing the stance justice. - Make "your" front stance the correct length and width. - Be lower first, then longer. - Edges outside of your feet are straight (your lead foot might be turned in slightly) - Your weight sits behind your front heel. <-- - Grab the floor with your feet and sink. - Get your butt under you and keep it there. Activate your ab muscles - Tendons in the feet, ankle, and knee must have light active tension.
For my body type, my butt sits right behind my lead heel if you drew a line. This produces knee over foot when I add in the other factors above. Is it 75% 70% 72%? No idea. It is dynamic and I can step or shift from stance to stance quickly and efficiently.
You should have an active tension to the floor. Beginner karate-ka make "skeletal strength." They have reached a point flexibility wise where they can make certain stance shapes. But they can't move from stance to stance efficiently.
Test your front stance. Can you move in any direction with out "double stepping," or standing up? When in front stance (full hip and half) what happens when you lift your front foot? If your weight is forward, you should go forward. If your weight is in the middle, that's kiba-dachi. Make a spring using your foot, ankle, knee, and hip joints.
Kagawa is something else. Love his teaching style. https://www.youtube.com/watch?v=qKdU7Wm7L80
Moving from move 2 to 3 in Heian Shodan...think step behind with the movement starting in your hips. I turn on the middle of my foot or whole foot. Your hip action will make your feet work.
Sincerely.
