This article is from the Outdoor Activities for Young Children FAQ, by Gloria Logan glogan@atk.com with numerous contributions by others.
> Jeffrey is normal height. I
> saw a few kids zooming around on them at the park this weekend -
> without the training wheels. They looked like they were about 5 y.o,
> or close to it.
Kids don't last very long on 12" bikes, if you get your son started at
age 3, by age 5 (maybe even before that) he will be ready for a 16"
bike. The best bet for a 12" bike is to look at yard sales and pick one
up for $10-20. If you have other smaller children that might justify a
new bike for future hand me downs, or aren't big on used stuff, a toy
store 12" bike for under $70 will last as long as your 3 year old will
want to ride it. It depends more on his arm length than his leg length
- you can adjust the seat downwards, but you can't make it get closer
to the handlebars.
 
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