Well there's your problem, you're supposed to lift up the training wheels over time. At the beginning they may be used all the time but by the end they should only be there to catch a bike that's falling over.

If the kid would alternate which training wheel is touching, then that would work. But once a side is picked they seem to center their balance between the back wheel and the one training wheel. I started off just barely raising it, and every couple weeks would adjust it another quarter inch or less. eventually they picked a side to lean and stayed with it.

That is where I was hoping to find spring loaded training wheels so that it forces the kid to constantly try to balance. Start off with really stiff springs and then weaken them over time.