2017 THOR Winter Olympics Presented by Pro Circuit is proud to announce we have added the 51cc (4-6) Shaft Drive Ltd class. This class will be a three moto format and will be raced on the SX track only. The Top 3 riders in each moto will receive a gold, silver and bronze medal respectively. The overall champion will be awarded the AMA Number 1 plate. The top 10 riders will be recognized at the SX awards on Wednesday evening.