My son will be 4 in a month. He currently rides a specialized hotrock 12”. It has the flat bars like a mountain bike and coaster brakes. He isn’t big for his age but the bike looks extremely small for him. I was looking at getting something like a 14” kink. There isn’t a shop within hours of me to actually go check something out. The searching I did showed the specialized 12” to be smaller than most 12” bikes. I’ve been thinking about maybe getting true bmx bars deleting the coaster and adding a handbrake. Just looking for suggestions on what to do.