You people are advocating keeping a WEAK leg kick? Are you kidding me?
The first time I sparred i was knocked out by a front leg kick to the face.
In order to get power from the front kick, you have to use it like ive heard a lot of TKDers on this forum suggest, and how i was taught in my Thai gym (Pongsan Ekyotin Thailand and USA champ).
1. This first movement is like a knee. You lift your knee up with your foot and shin relaxed, and thrust your left hip out as far as the distance requires. The harder you thrust, the more forward momentum you will create.
2. This is where sideways momentum comes in. You pivot on the ball of that right foot and WHIP your body (HIPS, CORE, SHOULDERS) to the right, launching your (still rising up) knee to the side, bringing the shin with it for contact.
!: 1 and 2 are done in very smoothe consistents of each other. Practice this with a partner on a large pad or with the thai pads. Prracticing on the bag is hard because your mind doesnt really get the distancing for it yet, nor the angles.
There are exercises that you can do to practice this before actual contact training.
Stand in front of a mirror and do the steps above, pivot on the right foot all the way around (with / without letting your shin come out) and come back to starting position. This will get you used to the motion and logistics.
DO NOT ALLOW WEAKNESS IN YOUR GAME!