Back in the 1970's it was just bike motocross because it was for the kids who were racing the events. The NBA and the ABA were the sanctioning bodies and every kid registered and rode with a number plate. It was the wild time of the sport where new stuff came out every week and we spent hours every week getting the kids ready for the next event, I learned how to blow grips on and off with ease and even how to true a wheel using the bleachers at the ABA races in Indy. Smiles, MH