Is 4 years old too young to ride without training wheels? I don't know if it is or not, but if it isn't then maybe a few weeks without pedals might be enough to get her riding.
We're going to try the no pedals thing this year with my almost 6 year old, the thing is he's so easily distracted, he runs into things because he's looking at a dog or drives into traffic because he saw a bug he wants to pick up