Choose a half marathon or 10k trail run along the trail networks in the north and south of the Greylock Glen. These routes showcase some of the best singletrack in north Berkshire. Runners will find fun and flowy terrain that blends ups and downs and smooth flats along machine and hand built trails. All proceeds of this event support the stewardship provided by the Thunderbolt Ski Runners of the mountain bike and ski trails around the Greylock Glen and Mt. Greylock.