Motorcycle superstore and rocky mnt ATV both have kids sections which I used to buy their riding gear. For helmets, the best luck I have had was going into a shop, because all of them fit differently. Plus you can ask someone who sells helmets all day, how they think they fit. (Reassurance ) My kids all wear Polaris youth helmets. They come with growth inserts. Little peices of foam you can add or take out as their skulls form. They have the best selection, at least in my area. They gave me a discount for buying them all together.