Originally Posted by Retro Grouch

Two things:

1. Training wheels are sized to the bicycle they go onto. I'm thinking that training wheels that are designed to fit a 16" or 20" bike aren't going to fit onto a 12" bike very well.

2. What's the point? My experience has been that training wheels just prolong the amount of time it takes a kid to learn to ride. Forget training wheels. Take off the pedals and lower the seat so that the kid can put both feet flat on the ground. Let him scoot along like that until he can lift his feet and coast confidently for 20' or so. Put the pedals back on, gradually inch up the seat, and he'll be good-to-go.