Small Bikes For Boys Buy Help! Need To Know What Size Bike To Buy!?

Help! need to know what size bike to buy!? - small bikes for boys buy

I have to give just two letters from the Angel Tree (Christmas Hello Army program) and the kids want bikes. There is a 12-year-old wears a size, the 16-18l. I think 20 "wheels is too small? 20" is the standard size for children. Should I a 24? "Does anyone know the size of a child is wearing that size? The 2nd child is a girl of 7 years and use size 12 .... I think the 20 is" good for them. I do not want something that is buying too small! Thank you.