100K
Offering 11,000’ of vertical gain, adventure awaits as you experience some of the most scenic and challenging sections of the 100-mile course in this 100K version of Grindstone by UTMB.
Race Category
Running Stones
Finals Access
Course Description
Starting at the historic Natural Chimneys, the 100k course gets you warmed up before tackling a short but steep climb in order to run along the single-track spine of Narrow Back Mtn. Once down the other side you face the monster Wolf Ridge climb where you connect to Timber Ridge turning left and staying left as you crest Sand Spring Mtn and descend on Sand Spring Trail. Take the Tillman forest access to North River Gap and jump on the iconic Wild Oak National Recreation Trail to climb Lookout Mtn and Hankey Mtn before descending the old-school flow of Magic Moss. Follow the North River forest access to Camp Todd where you rejoin the Wild Oak Trail climbing the infamous Horse Trough Hollow, up and over Little Bald Knob, across Chestnut Ridge to Grindstone Mtn and back to North River Gap. Retrace the Tillman forest access to pick up the Tillman Trail climbing back over Narrow back Mtn to Lick Run before exiting the forest at Bear Trap and cruising your way back to the finish in front of the Natural Chimneys.
*Courses are subject to change.
GPX File
Download the 100 Mile course GPX file below. Remember to ALWAYS follow course markings on the day of the race, as there might be slight alterations from the Course Maps and GPX File.
Your recorded distance may vary from our reported distance by as much as +/- one mile due to your device recording interval, the terrain, and dense tree canopy cover.
Last updated: 06/30/2025
Revision History
- Added elevation data
