Mammoth TUFF is an annual gravel cycling event held in Mammoth Lakes, California, produced by Tuff Ventures (Sheek Group LLC), co-founded by David and Amanda Sheek. The event offers multiple course distances — approximately 40, 70, and 90 miles — traversing the volcanic terrain of the Long Valley Caldera and Eastern Sierra high country at elevations starting around 8,000 feet. It is an official UCI Gravel World Series qualifier. The weekend includes pre-rides, the Mammoth BUFF beer run, music, and a post-ride celebration in The Village at Mammoth. Ten percent of entry fees are donated to public land stewardship organizations.