Get A Skate style helmet (cool look) and make sure it is CPSC Certified (bike safety). You get the cool looks of  a skate helmet with impact protection of a bike helmet. Google the S-One Kid Helmet. My 2 year old and 8 year old have them and loove them, They fit nice and deep on their heads so they don't wobble around. The fit is great. And there is a CPSC certified sticker on the inside.