UTMB World Series (Grindstone Trail Running Festival)
Grindstone Running Festival by UTMB - 100M
Mount Solon, VA (Natural Chimneys Park)
Race guide
Updated 29 June 2026
The Grindstone Running Festival 100M is one of the most demanding century races on the UTMB World Series calendar, covering 167 km with 5,771 m of climbing through the Appalachian ridgelines of Virginia's Shenandoah Valley region, starting and finishing at Natural Chimneys Park in Mount Solon, VA. The race is an out-and-back structure, meaning every climb you ascend on the way out becomes a descent — and eventually another climb — on the way home, with a high point of 1,321 m reached near North River Gap on the return leg. What makes Grindstone so ruthless is not any single climb but the relentless accumulation of vertical across nearly every kilometer of the course, combined with the psychological weight of knowing you must retrace your steps from Elliott's Knob all the way back to the finish. This is a race that rewards restraint, patience, and precise energy management over raw speed.
Course & Terrain Overview
The course rolls out of Natural Chimneys Park (409 m) and immediately begins working up toward Wolf Ridge at 15 km (655 m), signaling what the next 152 km will ask of you. Runners climb steadily to North River Gap at 30 km (1,133 m), continue across Little Bald Knob at 43 km (1,127 m), and descend to Lookout Mountain at 56 km (653 m) before pushing back up through Dowells Draft (68 km, 996 m) and Dry Branch Gap (79 km, 837 m) to reach the turnaround at Elliott's Knob area at 88 km (1,086 m). The terrain is classic Virginia Blue Ridge: rocky singletrack, rooty forest trail, and exposed ridgeline with minimal runnable stretches on the climbs. Footing demands constant attention, particularly on the descents where loose rock and embedded roots make aggressive downhill running a fast way to a rolled ankle. The trails are genuinely technical in places, not just steep.
Decisive Climbs and Where the Race Is Won or Lost
The out-and-back format creates a deceptive symmetry — the hardest section of the entire race is not at the turnaround but on the return, when fatigued legs must re-climb ground already surrendered. The stretch from Dry Branch Gap (return, 97 km, 670 m) back up to Dowells Draft (return, 108 km, 1,106 m) is a gut-check that eliminates runners who spent themselves in the first half. More critical still is the climb to North River Gap on the return leg (137 km, 1,318 m) — this is the highest point of the entire race and arrives at a moment, roughly 30 km from the finish, when glycogen reserves are critically low and the temptation to walk everything is overwhelming. Runners who have paced intelligently through Lookout Mountain and Dowells Draft on the way out arrive at these late climbs with something left; runners who pushed early arrive with nothing. The final descent from Wolf Ridge return (152 km, 540 m) back to Natural Chimneys Park is runnable and can be used to bank time against the Sunday 06:00 cutoff, but only if the legs have been protected.
Pacing Strategy
The cardinal rule at Grindstone is that the early valleys and runnable sections are a trap. The terrain between Natural Chimneys and North River Gap on the outbound leg feels inviting — treat it as a deposit, not a withdrawal. Run the flats easy, power-hike the climbs, and resist any urge to race competitors in the first 50 km. A patient, even social first half is the deposit that funds a strong second half; going out too easy is not a risk here, it is the strategy. The proven approach is to treat the turnaround at Elliott's Knob not as a midpoint celebration but as the moment the real race begins. From 88 km onward, shift your mental frame: break the remaining distance into manageable blocks rather than confronting the full 79 km back to the finish. Thinking 'two more aid stations and I reassess' converts an overwhelming return journey into a series of achievable targets. Runners who internalize this structure consistently outperform those who try to race the outbound leg.
Fueling & Aid Station Approach
With crew access at Natural Chimneys (start/finish), North River Gap (30 km and 137 km), Dowells Draft (68 km and 108 km), and Lookout Mountain return (120 km), you have reliable windows to replenish drop bags and meet your crew — plan each crew interaction as a pit stop with a specific list, not a social visit. Between crew points the gaps stretch to 10–15 km of demanding terrain, so carry sufficient calories and fluid for the worst-case scenario. Fueling on the climbs is non-negotiable: the repeated 300–400 m elevation gains will drain glycogen faster than the distance alone suggests. Prioritize getting calories in at Dowells Draft both on the way out (68 km) and on the return (108 km), as these bracket the most demanding sequence of the back half. Sodium management matters especially on the return, when muscle cramps from accumulated effort become a real risk; stay ahead of electrolyte needs from the halfway point onward rather than reacting to them.
Conditions to Expect
Grindstone takes place in early October in Virginia's Shenandoah Valley, which means temperatures can swing dramatically across the event window. Daytime temperatures on the ridgelines can be mild to warm, but nights at elevation — particularly along the exposed sections near Little Bald Knob (1,127 m) and approaching North River Gap (1,133 m to 1,321 m) — drop sharply and wind exposure is real. Carry a mid-layer and wind shell regardless of the forecast; hypothermia risk during the night sections is genuine for a runner who is moving slowly or managing a low patch. Rain is common in October and transforms the rocky, rooty singletrack into a significantly more technical and time-consuming surface, adding to both effort and injury risk on descents. Headlamp management is critical: most runners will spend at least one full night, possibly two depending on pace, in darkness on technical terrain, so carry spare batteries or a backup light and know your aid station distances for after dark.
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Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-05) · official source
0 km · 408 m · —
9.2 km · 535 m · —
18.6 km · 553 m · Fri 21:30
32.9 km · 1295 m · Sat 00:30
39.3 km · 1208 m · —
53.2 km · 491 m · Sat 04:00
62.3 km · 794 m · —
74.5 km · 612 m · Sat 09:00
85.5 km · 793 m · Sat 11:00
96.9 km · 725 m · —
105.8 km · 786 m · Sat 15:30
116.8 km · 610 m · Sat 18:00
125.4 km · 706 m · Sat 20:00
133.5 km · 717 m · Sat 21:30
149.7 km · 491 m · Sun 01:45
162.1 km · 535 m · —
169.3 km · 409 m · Sun 06:00
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