(written from a Production point of view)
Reagan Sieg (born 18 December 1978; age 43) is a professional dirtbiker who worked as one of the PX70 motorcycle stunt doubles for James T. Kirk actor Chris Pine on the 2016 Star Trek feature film Star Trek Beyond along with Antal Kalik and Leif Havdale under Stunt Coordinator Mike Gunther.
He has started his interest in bikes at early age when he rode a Honda 50 around his family apple orchard. He later became a professional in motocross, FMX, Enduro, and snowbiking and became a Canadian motocross champion and professional FMX rider.  He also became a sales rep for Timbersled in British Columbia. 
In 2015, he set a world record when he jumped with his snowbike to a distance of 25 metres at the 2015 World Snowmobile Invasion in Whitecourt, Alberta. 
Sieg was also featured in several documentaries about snow bikes and motorcycles such as Global Addiction (2002), Freestyle Prague (2006), Elements (2010), and Trax: The Evolution of Snow Bikes (2015).