The regular season for dirt bikes is over. The first half is Supercross (SX) where they race in stadiums. The second half is Motorcross (MX) where they race on longer tracks outdoors. Both SX and MX have champions but last year they combined points from SX and MX and called it SMX and did a three race playoff for those who qualify. Personally, I'm not a fan of the new system. All three have two champions, one for 450cc and one for 250cc.