Grindstone Trail Running Festival
Grindstone Trail Running Festival – 100K
Natural Chimneys Park, VA
Race guide
Updated 18 July 2026
The Grindstone 100K is the mid-distance flagship of the Grindstone Trail Running Festival, a rugged mountain race that starts and finishes at Natural Chimneys Park in Virginia. Covering 100 km with 2929 m of positive climbing and a high point of 1319 m, it delivers the relentless, rocky, root-strewn climbing that has given the Grindstone name its reputation, on an out-and-back-flavoured course through the George Washington National Forest ridges. This is a race defined by repeated big climbs rather than a single summit, with the mountains stacking up steadily across the day and night. Runners who target Grindstone are usually looking for a genuine test on technical Appalachian terrain, and the 100K distance packs nearly 3000 m of vertical into its route while remaining a step down from the festival's longer offerings. It is a demanding but rewarding day for anyone comfortable on steep, sustained mountain trail.
The Course: An Out-and-Back Through the Ridges
Grindstone 100K starts and finishes at Natural Chimneys Park at 409 m, and the aid-station names make the out-and-back rhythm clear: Lick Run 1 at 9.2 km, Wolf Ridge at 18.6 km, Sand Spring at 34.2 km, North River Gap 1 at 41.1 km, Lookout Mountain at 50.3 km, Magic Moss at 61.9 km, Camp Todd at 70 km, North River Gap 2 at 86.1 km, Lick Run 2 at 98.5 km, and the finish at 100 km. North River Gap appears twice, at 41.1 km and again at 86.1 km, confirming that the course returns through the same key valley, and Lick Run bookends the route near the start and finish. The elevation profile is a sequence of climbs and drops between roughly 409 m and the 1319 m high point. Notable high points along the way include Lookout Mountain at 794 m (50.3 km), Camp Todd at 772 m (70 km), and Magic Moss at 683 m (61.9 km), while the low collars come at North River Gap (490 m and 512 m). Rather than one dominant ascent, the 2929 m of climbing is distributed across a whole series of ridge climbs and gap descents, which is exactly what makes Grindstone terrain feel relentless.
Where the Race Is Decided: The Middle Mountains
The heart of the race is the block from North River Gap 1 at 41.1 km (490 m) up to Lookout Mountain at 50.3 km (794 m) and on through the high country to Magic Moss at 61.9 km and Camp Todd at 70 km. This central stretch contains the biggest sustained climbing on the course, including the push toward the 1319 m high point, and it lands squarely in the middle of the effort when fatigue is building. Runners who arrive at North River Gap 1 already frayed tend to unravel across these climbs. The return leg is the second crux. From Camp Todd at 70 km the course heads back toward North River Gap 2 at 86.1 km (512 m), meaning another significant descent into the gap followed by the climbing needed to close out the final 14 km through Lick Run 2 (98.5 km) to the finish. The repeated gap-to-ridge pattern means there is no genuinely easy closing section; the last quarter still demands climbing on tired legs. Managing effort through the middle mountains so you can still move on the return is what separates a strong finish from a survival march.
Pacing and Fuelling: Working the Cut-offs and Crew Points
The cut-offs give a clear structure for the day. Wolf Ridge (18.6 km) closes Sat 09:00, Sand Spring (34.2 km) Sat 11:45, North River Gap 1 (41.1 km) Sat 13:00, Magic Moss (61.9 km) Sat 16:30, Camp Todd (70 km) Sat 18:00, North River Gap 2 (86.1 km) Sat 21:00, and the finish at 100 km closes at midnight. The three crew points are North River Gap 1 (41.1 km), Camp Todd (70 km), and North River Gap 2 (86.1 km), and because North River Gap is a crew stop on both the outbound and return passes it is the logistical anchor of the race. For fuelling, treat the two North River Gap visits as your major resupply and reset points, and plan for the long climbing blocks between them. The 21 km from North River Gap 1 (41.1 km) to Magic Moss (61.9 km) crosses the highest and most sustained terrain, so leave the gap carrying enough calories and fluid for a slow, climb-heavy section. From Camp Todd at 70 km you face 16 km back to North River Gap 2, another stretch to fuel deliberately. Use the generous but firm cut-offs as checkpoints: staying comfortably ahead of the Sand Spring and Magic Moss times is the best early signal that your pacing is sustainable.
Conditions to Expect on Appalachian Mountain Trail
Grindstone runs on classic George Washington National Forest terrain: rocky, technical mountain trail with sustained climbs and descents between the valley floor at around 409 m and the ridgelines up to 1319 m. The repeated climbing over 100 km means footing and technical descending are ongoing challenges, and the rugged surface underfoot is as much a part of the difficulty as the total vertical gain. Sturdy footing skills and durable quads for the many descents into the gaps are essential. With the finish cut-off running to midnight, expect a large portion of the field to be moving into darkness, so a reliable lighting setup and night-running readiness are important for the later climbs and technical descents. Temperature swings between the exposed ridges and the sheltered valley gaps are typical of Appalachian mountain racing, so plan layering that works from a warm daytime start through cooler night sections. The combination of technical terrain, nearly 3000 m of cumulative climb, and a long day-into-night effort is what defines the Grindstone experience.
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Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-17) · official source
0 km · 409 m · —
9.2 km · 535 m · —
18.6 km · 553 m · Sat 09:00
34.2 km · 594 m · Sat 11:45
41.1 km · 490 m · Sat 13:00
50.3 km · 794 m · —
61.9 km · 683 m · Sat 16:30
70 km · 772 m · Sat 18:00
86.1 km · 512 m · Sat 21:00
98.5 km · 447 m · —
100 km · 409 m · Sat 00:00
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