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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

ws100KM

Running Stones

3

Finals Access

Distance

100 KM

Elevation Gain

3350 M+

Start Date

Saturday 20th September 2025

Race Start

Natural Chimneys Park, VA - 06:00

Max Allowed Race Time

18 Hours

Price

$380

Course Description

Course Description

*2025 Courses Coming Soon.

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.

Mandatory Gear

  • Running pack for carrying supplies for the duration of the race
    • Pack can be a backpack, vest or waist/belt pack
  • Mobile / Cell phone (smartphone strongly recommended)
    • Mobile / Cell phone with international roaming that works in the United States of America
    • Each runner should save the organization's safety phone numbers
  • Personal collapsible cup (15 cl / 5 oz minimum)
  • Minimum water supply of 1 liter
  • 1 working headlamps (torches) with spare cells/batteries for each headlamp. (Recommendation of 200 lumens or more for main headlamp)
  • Food reserve. (Recommendation of 800 kcal: 2 gels + 2 power bars each of 65 g)
  • Jacket with hood for bad weather in the mountains. The jacket must have an integrated hood or one which attached to the jacket by the original system designed for that purpose by the manufacturer
  • Hat (beanie, cap, bandana, or Buff®)
  • Survival blanket of 1.40 m x 2 m / 55 inches x 80 inches minimum or survival bag
  • Whistle
  • Gloves
  • ID Card / Passport

(including, but not limited to)

  • Spare warm clothing (essential in case of cold and rainy weather or in case of injury)
  • Trekking poles
  • GPS watch
Mandatory Gear
Aid Station Chart

Aid Station Chart

Learn more about each Aid Station, elevation gain and loss, cut-off times, and where drop bags and crew are allowed on course

Crew Access Driving Directions

Please review the 100M Crew Access Driving Directions to prepare for race weekend.

DIRECTIONS
Crew Access Driving Directions
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