We are giving my daughter a bike for her 4th birthday in a couple of weeks and will have to resort to purchasing online. So withhout seeing a bike in person I am concerned what size I should buy for her. I see that 12" and 16" are the standard sizes but I am not sure which to pick. I don't want her to grow out of it immediately but I don't want it to big that she is intimidated to ride it. Is a 12" ridiculously small? She is of average height for a 4 year old.