Mongoose wheel replacement

[Bill]

Going to smaller wheel on a mongoose is really not practical at all. The reason is the the frame dropouts (where the front and rear axle bolts connect to the frame) are spaced only for 18" wheels. The smaller you go the shorter the axle. Now granted if a 16" wheel did slide into place and you had to tighten up the nuts on the axle it would bend the frame too far inward. Best bet is to keep your bike until he gets older. Some thoughts in my mind are, put the seat down as far as it goes and there are blocks that go on the pedals so he can reach them.
http://www.amazon.com/Pyramid-pdh4111-Pedal-Blocks/dp/B000MK29H0 .

Others here may have ideas too.