UTMB Grindstone 100 Mile (Grindstone Trail Running Festival by UTMB)
Mount Solon, Virginia · September · 100 mi
- Distance
- 104 mi (167 km)
- Out and back
- Climbing
- 6,400 m (21,000 ft)
- Mountain: 38 m per km (202 ft per mi)
- Overall cutoff
- 36 hours
- 20:48 per mi (12:55 per km) average
- Finish rate
- 79%
- of starters in 2019
Why runners love it
- Starts and finishes beside the Natural Chimneys limestone towers, with 104 mi (167 km) of ridges between.
- Eleven published cutoffs at a steady 18 to 21 min per mile (11 to 13 min per km).
- Pacers allowed from mile 45.6 (73 km), so about 58 mi (93 km) of company.
- Ridge running over Reddish Knob and Elliott's Knob with 6,400 m (21,000 ft) of gain in 36 h.
- Open online entry, a Western States qualifier, and 4 UTMB Running Stones.
Watch out for
- Crew allowed at only 3 named places (5 stops); meeting your runner elsewhere risks disqualification.
- 6 pm start means two nights for most; the first cutoff at mile 11.4 (18 km) allows only 3:30.
- Rocky, slick descents such as Elliott's Knob drop about 610 m (2,000 ft) in 3.2 km (2 mi).
- Mandatory 8 hours of trail work in the event year, or a $225 buyout.
- Weather swings: tropical-storm rain in 2023, hot and humid in 2025, near freezing wind on ridges.
Race
How runners feel about it, how well it is run, and the community around it. Counts for 25% of the overall score.
Toughness for its distance: Very tough
- Runner satisfactionLoved4.4
Reports from 2012 to 2025 are almost all positive about the course and finish; even the brutal 2023 storm year drew praise. · Medium confidence
- OrganizationWell run4.1
Detailed runner guide, 11 published cutoffs, chip timing and clear crew rules; permit limits add some friction. · Medium confidence
- Community and vibeWarm3.8
Expo, live music and a finish beside the Natural Chimneys, but now a large UTMB series event with about 300 starters in 2023. · Medium confidence
Support
Aid stations, crew access, drop bags and pacer rules. Counts for 25% of the overall score.
- Aid stationsStandard3.4
15 stations over 104 mi (167 km), about 7 mi (11 km) apart, longest gap 9.7 mi (15.6 km); real food reported. · Medium confidence
- Crew accessSome points2.9
Crew allowed only at North River Gap, Dowells Draft and Camp Todd (5 stops in 104 mi / 167 km (104 mi)); elsewhere risks disqualification. · High confidence
- Drop bagsSome stations3.2
Drop bags at only 5 stations plus the finish, out of 15 on the 2026 chart. · High confidence
- PacersMuch of the race3.9
One pacer at a time from mile 45.6 (73 km), so for the last 58 mi (93 km), joining at set stations. · High confidence
Course
Course marking, scenery, and how runners rate the trail itself. Counts for 15% of the overall score.
- Course markingClear3.9
Flags, reflective ribbons and glow sticks per the runner guide; one 2025 report found overgrown trail, but no lost runners are reported. · Medium confidence
- SceneryBeautiful4.3
Ridge running over Reddish Knob and Elliott's Knob with long views when clear; several reports describe fog-covered summits instead. · Medium confidence
- Trail experienceGreat4.2
Runners praise flowing singletrack and Magic Moss; deductions for steep, slick descents in rain and overgrown sections. · Medium confidence
Course traits, not part of the score
- FootingTechnical1.7
Rocky, narrow singletrack with steep slick descents such as Elliott's Knob, about 610 m (2,000 ft) down in 3.2 km (2 mi). · High confidence
- RunnabilityLots of hiking2.1
Six or more long climbs and descents; mostly power hiking up and careful descending, with runnable stretches near the end. · Medium confidence
- ClimbingHilly1.9
Climbs 202 ft per mi (38 m per km), from the official elevation gain. · High confidence
Conditions
Race-day temperature and how predictable the weather is. Counts for 14% of the overall score.
- Race-day temperatureWarm or cold3.3
Late September ranges from hot and humid to near freezing on the ridges at night. · Medium confidence
- Weather reliabilityVariable2.6
Rain in several years, tropical-storm wind and rain in 2023, then heat in 2025; the guide warns of everything from heat to snow. · Medium confidence
Course traits, not part of the score
- AltitudeModerate3.2
Elliott's Knob is about 1,360 m (4,460 ft), a figure from a photo caption; the race gives no high point. · Low confidence
Cutoffs
How generous the overall and intermediate cutoffs are for the terrain. Counts for 13% of the overall score.
- Overall cutoffNormal3.3
36 h for 104 mi (167 km) and 6,400 m (21,000 ft) is about 21 min per mile; cut from 38 h. · Medium confidence
- Intermediate cutoffsReasonable3.0
11 cutoffs at a steady 18 to 21 min per mile; the first, at mile 11.4 (18 km), gives only 3:30. · Medium confidence
Intermediate cutoffs (2026 (aid station chart, runner guide, regulations) and the 2027 race listing)
| Where | Distance | Cutoff |
|---|---|---|
| Wolf Ridge (mile 11.4) | 18 km (11 mi) | Fri 21:30 (3:30 elapsed) |
| Reddish Knob (mile 20.4) | 33 km (20 mi) | Sat 00:30 (6:30 elapsed) |
| North River Gap 1 (mile 32.4) | 52 km (32 mi) | Sat 04:00 (10:00 elapsed) |
| Dowells Draft 1 (mile 45.6) | 73 km (46 mi) | Sat 09:00 (15:00 elapsed) |
| Dry Branch Gap 1 (mile 52.6) | 85 km (53 mi) | Sat 11:00 (17:00 elapsed) |
| Dry Branch Gap 2 (mile 64.9) | 104 km (65 mi) | Sat 15:30 (21:30 elapsed) |
| Dowells Draft 2 (mile 71.9) | 116 km (72 mi) | Sat 18:00 (24:00 elapsed) |
| Magic Moss (mile 77.1) | 124 km (77 mi) | Sat 20:00 (26:00 elapsed) |
| Camp Todd (mile 82.1) | 132 km (82 mi) | Sat 21:30 (27:30 elapsed) |
| North River Gap 2 (mile 91.8) | 148 km (92 mi) | Sun 01:45 (31:45 elapsed) |
| Finish (mile 104.0) | 167 km (104 mi) | Sun 06:00 (36:00 elapsed) |
Not part of the score
- First timer friendlyDoable2.7
Several first-time 100 finishers are reported, but 6,400 m (21,000 ft), two nights and technical descents make it a hard first hundred. · Medium confidence
- Getting inUsually open3.8
Open online entry with no lottery, though 8 hours of trail work is required and a sell-out is possible. · Medium confidence
Stay and travel
Getting there, places to stay, race-day logistics and value. Counts for 8% of the overall score.
- Travel easeAwkward2.4
Rural Mount Solon in the Shenandoah Valley; the race pages give no airport distances, so expect a rental car and a long drive. · Low confidence
- Places to stayBook early3.0
Rental houses and Airbnbs are what crews report using; the race lists accommodation but few runners describe it. · Low confidence
- LogisticsSimple3.7
One start and finish with a single drop bag drop-off, but crew parking at three remote stations is tightly controlled. · Medium confidence
- ValueFair3.0
Entry fee is not published on the race page; 8 hours of trail work (or a $225 buyout) is required. · Low confidence
Key facts
Checked against the 2026 (aid station chart, runner guide, regulations) and the 2027 race listing edition on the official race site. Rules change, so confirm before you enter. Blank means the race does not publish it.
- Location
- Mount Solon, Virginia, United States
- Region
- Mid-Atlantic US
- Typical month
- September
- Latest or next date
- 24 September 2027
- Start time
- 18:00
- Distance
- 104 mi (167 km)
- Course shape
- Out and back
- Surface
- Trail: Mostly Appalachian singletrack on ridges in the George Washington National Forest, with short gravel and forest road sections (for example the gravel stretch before Horse Trough and the Cold Springs forest access).
- Footing
- High point is Elliott's Knob, which the race site names as the course's highest elevation but does not give a height for; 1,360 m (4,463 ft) is the summit elevation from the Wikimedia Commons caption. Runner reports describe rocky, narrow singletrack, a 2,000 ft (610 m) drop in 2 mi (3.2 km) down Cold Springs Trail, slick mud in wet years and overgrown sections in 2025. Climbing is spread across at least six long climbs and descents; the biggest single stretches are Wolf Ridge to Reddish Knob (3,012 ft / 918 m (3,010 ft) gain over 9.0 mi / 14.5 km (9 mi)) and Camp Todd (2,704 ft / 824 m (2,700 ft) over 9.7 mi / 15.6 km (9.7 mi)). Gain figures from the 2026 aid station chart.
- Elevation gain
- 6,400 m (21,000 ft)
- Climbing rate
- 38 m per km (202 ft per mi)
- High point
- 1,360 m (4,460 ft)
- Overall cutoff
- 36 hours
- Pace to make the cutoff
- 20:48 per mi (12:55 per km)
- Cutoff notes
- Eleven timed cut-offs from the 2026 runner guide and aid station chart (start Friday 18:00; elapsed times are our arithmetic). Implied pace is about 18 to 21 min per mile (11 to 13 min per km) throughout. Leaving an aid station after the cut-off ends your race, and the organiser may adjust times. The 38 h limit of earlier years was cut to 36 h.
- Aid stations
- 15
- Longest gap between aid
- 16 km (9.7 mi)
- Drop bags
- Some stations
- Crew access
- Some points
- Pacers
- Allowed after mile 45.6 (Dowells Draft 1); one pacer at a time, 100M only
- Support notes
- 15 aid stations (AS1 to AS15) listed on the 2026 chart; longest gap is Camp Todd to North River Gap 2, 9.7 mi (15.6 km). Drop bags and crew at North River Gap 1 (mile 32.4), Dowells Draft 1 (45.6), Dowells Draft 2 (71.9), Camp Todd (82.1), North River Gap 2 (91.8) and the finish. Crew and spectators are only allowed at North River Gap, Dowells Draft and Camp Todd; being met anywhere else risks disqualification. Pacers may join at Dowells Draft 1 or 2, Camp Todd or North River Gap 2, must be registered at the expo and wear a pacer bib. Drop bags go in at the start by 16:00 Friday.
- Water crossings
- A few
- Water notes
- Not described on the official pages. Runner reports mention damp creek-bottom sections late in the race (around mile 96 / 154 km (95.7 mi)) and wet, muddy trails in rainy years.
- Night running
- Two or more nights
- Mandatory gear
- 1 L water capacity, reusable cup, running pack, cell phone, hooded jacket, 2 headlamps with spare batteries, 800 kcal extra food (2 gels and 2 bars), hat, whistle, survival blanket (2026 and 2027 UTMB North America list; weather kits may be added)
- Entry
- Open
- Qualifier needed
- None stated on the registration page. Online registration, no race-day registration, closes the Sunday before the race or when sold out. At least 8 hours of trail work in the calendar year is mandatory (or a $225 buyout).
- Qualifies for
- Western States, UTMB Running Stones (4 stones)
- Finish rate
- 79% of starters in 2019
- Weather notes
- Late September in the Shenandoah Mountains. Reports range from hot, humid conditions (2025) to tropical-storm wind and rain (2023) to 40s and 30s F (about 4 to 0 C) on exposed ridges at night. The runner guide warns of weather from heat to snow on mountain tops.
- Nearest airport
- Not stated on the pages we read (Shenandoah Valley, Charlottesville and Dulles are the usual choices); a rental car is needed
- Stay notes
- Start and finish at Natural Chimneys Park, Mount Solon. Crews in 2023 used a rental house and an Airbnb nearby. The official site has an accommodations page we could not read in full.
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What runners and reviewers say
- TeamRunRunRaced 2025 · blog · Positive
Burrer finished 8th in 25:43:33 and rates it 5 of 5. He found mostly singletrack with some overgrown sections that slowed him, a rough stretch around miles 53 to 66 (85 to 106 km (65.9 mi)), and smooth, runnable final miles. 15 aid stations about 6 to 8 mi (10 to 13 km (8.1 mi)) apart, crew at 5; it was hot and humid so he suggests crews bring ice, and poles are worth carrying.
“Above all, take the climbs easy!”
- Scott's Running (Substack)Raced 2023 · blog · Mixed
Perry crewed and paced a friend through Tropical Storm Ophelia: sideways rain, fog and gusts around 40 mph (65 km/h). The descent off Elliott's Knob was wet, slick and rocky, and later climbs were muddy. He praises the expo and volunteers and describes renting an Airbnb and driving between house and course; the race had about 300 starters and a 6 pm start.
- GoBroncoBillyRaced 2014 · blog · Positive
Browning won his 12th hundred here in a rainy, humid year. He describes narrow, rocky Appalachian singletrack that is technical in the dark, fog on the summits, a punch tool to prove the Reddish Knob summit, and medical weigh-ins at North River Gap. David Horton handed out hot chocolate at Dowells Draft; the camp setting with a lodge and tents suited him.
- MassUltraRaced 2016 · article · Positive
Roundup of New England runners at the rainy 2016 race: singletrack across the Blue Ridge with about 23,200 ft (7,070 m) of climbing, a 38 h limit then, and 179 finishers of whom 21 broke 24 h.
“East Coast 100-milers don't come much tougher than Grindstone”
- VHTRCRaced 2014 · article · Positive
Report on the 2014 edition after a one-year hiatus: rain for a few hours after the 6 pm start, a mild Saturday, then wind and low 30s F (about 0 C) on the ridges Saturday night. Robin Watkins broke the women's record in 22:53:13.
Show 4 more
- VHTRCRaced 2012 · blog · Positive
A revenge finish in 28:24:24 for a masters runner after a prior DNF. Aid stations sat roughly 5 to 10 mi (8 to 16 km (9.9 mi)) apart with crew access from mile 22 (35 km), the course had about 23,700 ft (7,200 m) of gain over shale and rocky singletrack, and his family crew and pacer got him through the second night.
- iRunFarRaced 2014 · article · Positive
AJW calls the course very technical, with three major climbs on the return leg and punishing creek-bottom sections near mile 96 (154 km), in rain and humidity. Aid stations such as Jonathan Basham's (mile 57 / 92 km (57.2 mi)) served egg burritos; family members paced the second half. He was pleased with the race.
“In the end I was pretty pleased with my race.”
- iRunFarRaced 2019 · article · Positive
AJW notes the unusual 6 pm start tests sleep deprivation, at least six extended climbs and descents, and a 38 h limit that is generous next to Wasatch (36 h for 26,000 ft / 7,900 m (25,920 ft)) and Angeles Crest. The 2019 race set a record 79 percent finish rate in mild weather.
- The Sean Stack (Substack)Raced 2022 · blog · Positive
Cate finished 5th in 21:28:18 in his first 100 mi (161 km). Course was steep climbs, long descents and some runnable sections such as Hankey to North River Gap; a dam bottleneck at the start is avoided by lining up near the front. Aid stations were well stocked (soup, sweet potato, quesadillas) and weather was good for September; he was proud but called the last miles very painful.
Ran UTMB Grindstone 100 Mile (Grindstone Trail Running Festival by UTMB)? Your notes on the footing, cutoffs and aid stations help the next runner decide.
Sources
Pages we used for facts and ratings.
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