Sweep Riders of the Sierra (SOS) is an all-volunteer riding group established to provide on-trail communications for endurance events on the Western States Trail and other Northern California locations. 

SOS Sweep Teams are composed of two to four riders that sweep one section of the trail before being relieved by a fresh team. Trail sections vary from 6 to 23 miles in length. Each team is responsible for following the last few competitors while maintaining radio contact with “net control” at the finish line in Auburn.

SOS Radio Operators are experienced riders and licensed amateur radio operators who use hand-held HAM equipment to remain in contact with net control while their mounted team traverses the remote and otherwise inaccessible trail. In the event of an emergency, they are able to provide information to net control in order to quickly summon emergency rescue units, such as MedEvac helicopters and Large Animal Rescue Service (LARS).

SOS Mounted Members provide crucial support in the event that a competitor is injured. On the rough and rugged terrain of the Western States Trail, it is often impossible for vehicles to rescue an injured or exhausted competitor. In that event, SOS members and their steeds are vital to help the competitor get to the next aid station.

Sound Like Fun?

Please check out our Qualifications Page for more information.

Events We Support:

-Western States Trail Ride (Tevis Cup)

-Gold Country 30/50 Endurance Ride (GCER)