My sister's 5 kids all ride bikes and each one has learned on a great little Schwinn-type of bike with 16inch wheels that I bought for 5 bikes about 12 years ago. The 5 year old really loves it and even though it is too small for him now, he constantly bugs the 3 year old about "getting a turn on it".

I really should take a picture of it one day, that bike has some great history to it now