Scotty,
Wilson made a good point. I personally think that there’s a distinction to be made between weight and momentum. Certain types of sidekick will propel your momentum forward (skipping sidekick, for example) but don’t require that you lean forward.
As far as weight distribution, personally I put it on the back leg so that if I miss, I don’t fall into a counter from the other person. (In that sense, I agree with Unstoppable, despite his decidedly arsehead delivery.)
That said, if you develop a tactic for dealing with it when you miss the target and then ‘fall in’ to punching range (e.g., covering up or weaving straight into your own punching combination), then it’s no harm, no foul I suppose.
My personal thought on getting pushed and unbalanced, particularly by someone heavier than you, relates more to recoil than weight distribution. I’ve noticed that a lot of people are taught to ‘stick’ their sidekick. (Perhaps for aesthetics, but I’ve heard it argued that it’s stronger that way; personally, I disagree.) My feeling is that sticking your sidekick (locking it out, even momentarily) allows the opponent to unbalance you. It gives the opponent a solid entity to manipulate, even if that manipulation is as simple as continuing to move forward into the kick. That solid bridge between him and you could allow him to push you off balance (and it needn’t even be deliberate on his part).
My advice would be not to stick the sidekick. Recoil it immediately. I think it results in a more jarring impact. But more importantly to this discussion, it doesn’t provide anything that can be used against you. Either your foot hammers in to his ribs and then back out or you miss and recoil immediately to retrieve your balance, get your feet back under you, and continue sparring.
Give it a go on the heavy bag or kicking shield. Actually, get someone to hold a kicking shield and walk toward you. Once you get the timing down, you’ll be able to stop them in their tracks without sticking it. And even when you get the timing wrong, I think it’ll leave you in a more defensible (or offensible, if you prefer) position.
I read a book once that suggested a way to practice the sidekick recoil. I did it, and I think it worked. The book suggested that you practice recoiling from an extended position. In other words, practice just the last half of the kick (fully extended to fully recoiled all the way back to sparring stance). Once you get used to that, try putting the whole kick together.
So that’s my advice (for whatever it’s worth). Weight distribution’s not forward. Emphasize the recoil. ‘Piston’ your kick rather than ‘sticking’ it.
I hope that helps.
Stuart B.