Mount Solon, Virginia · Trail
Official site ↗Grindstone
A September trail weekend at Natural Chimneys Park in Virginia's Shenandoah Valley: a night-start 100M and a 100K, both UTMB World Series races and Western States qualifiers.
Distances
100M
- Distance
- 167.4 km (104 mi)
- Vert gain
- 6,400 m (21,000 ft)
- Cutoff
- 36 hr
6:00 PM Friday start · WSER 2027 qualifier (sub-36:00)
100K
- Distance
- 100 km (62 mi)
- Vert gain
- 3,350 m (11,000 ft)
Saturday start · WSER 2027 qualifier (sub-18:00)
| Distance | Vert gain | Cutoff | Notes |
|---|---|---|---|
| 167.4 km (104 mi) | 6,400 m (21,000 ft) | 36 hr | 6:00 PM Friday start · WSER 2027 qualifier (sub-36:00) |
| 100 km (62 mi) | 3,350 m (11,000 ft) | — | Saturday start · WSER 2027 qualifier (sub-18:00) |
About
Grindstone fills a September weekend at Natural Chimneys Park in Mount Solon, Virginia, west of the Shenandoah Valley. The 100M is the anchor: 167.4 km with 6,400 meters of climbing through the national forest, out to Reddish Knob and back, starting at 6:00 p.m. Friday so every runner takes on the first night in the dark. The cutoff is 36 hours, and a 100K, 50K, and 21K share the weekend.
As a UTMB World Series event, top finishers earn Running Stones for the World Series Finals lottery, and the top three men and women in the 100M, 100K, and 50K qualify directly for the Finals. The 100M and 100K both count as Western States 100 qualifiers.
Course
From Natural Chimneys Park in Mount Solon, the 100M runs an out-and-back over the ridges to Reddish Knob: 167.4 km with 6,400 meters of climbing, a 6:00 p.m. Friday start, and a 36-hour limit. The 100K (100 km, 3,350 meters of gain) starts Saturday.
How to register
Registration runs on the UTMB platform. The 2026 races are September 17 to 20; registration for the following year opens September 18, 2026. Finishers earn Running Stones for the UTMB World Series Finals lottery.