Robert Daniels writes:

Is it better to ride a tricycle or a bike with training wheels until
the child is ready to tackle a two wheeler? When is the best time to
teach a child to balance?

Riding a tricycle is a special skill if the child is assertive and
wants to ride fast. It's a good introduction to vehicle dynamics.
Bicycling has a different control mode because it requires balance,
something only the fast tricyclists notice as they speed around
corners leaning into the turn.

At about three and then some, children are probably ready for a
bicycle if they are tall enough. Super small bicycles are hard to
balance because they have so little tip-over moment. Whatever you do,
don't make an unstable tricycle of a bicycle. When the time is right,
take a couple of ten minute outings with the child on the bicycle.
Hold the bicycle from the saddle to help balance and don't let the
child know when and if you let go.

Jobst Brandt

Palo Alto CA