Grindstone 100 Race Guide
Grindstone 100 is a storied 100-mile trail ultramarathon held each fall in the Shenandoah Valley. Runners leave Natural Chimneys Park under the towering limestone formations as dusk settles on September 19, 2025. This race pairs the solitude of single-track ridge running with rugged climbs that test even seasoned ultrarunners. The event is part of the UTMB® World Series and draws athletes seeking both personal achievement and the chance to earn a coveted Running Stone.
When It Is Run
The 2025 Grindstone 100 takes place on Friday, September 19. The 100-mile field starts promptly at 6:00 PM, allowing competitors to race through nightfall and sunrise before completing the course. Fall foliage colors add to the spectacle as runners negotiate mountain ridges and forest tracks under headlamps and flashlight beams.
How to Qualify or Register
Entry into Grindstone 100 is handled through the UTMB World Series registration system. Runners who hold a valid UTMB Index gain 48-hour priority access beginning February 6, 2025, at 12 AM ET, ensuring the best chance of securing a spot. Once priority registration closes, general registration opens on February 8, 2025, at 12 AM ET. All entrants must be at least 18 years old, agree to the race’s mandatory gear requirements, and complete online registration by the published deadline. Entry fees cover the race, aid station services, timing, finisher gifts, and post-race meals.
Particular Challenges
Grindstone 100 is renowned for its relentless climbs and technical terrain. Athletes face more than a dozen major ascents, including the brutal Elliott’s Knob climb to the course’s highest point, followed by steep descents like the Cold Springs drop of 2,000 feet in just two miles. Solitude on narrow ridge lines can be mentally taxing, and night running on rocky single-track demands constant focus. High elevation gains combined with unpredictable fall weather—ranging from warm valley nights to chilly ridge winds—add to the challenge, making proper pacing, nutrition, and equipment crucial.
Course Format
The course is a single-loop trail that begins and ends at Natural Chimneys Park. After an early ascent up Narrow Back Mountain, runners traverse a series of ridges—Wolf Ridge, Timber Ridge, Sand Spring Mountain—before joining the historic Wild Oak National Recreation Trail. The loop continues over Grindstone Mountain, Lookout Mountain, and Hankey Mountain, then heads south over Crawford Knob to Elliott’s Knob, the high point. From there, the route descends via Cold Springs Trail, loops back over Crawford Knob and Dowells Draft, and returns along the Wild Oak Trail before the final climb back to Natural Chimneys.
Elevation Profile
Grindstone 100 features approximately 21,000 feet (6,400 meters) of cumulative elevation gain and loss. The race’s low point at Natural Chimneys Park sits near 1,650 feet (504 meters), while its highest elevation, Elliott’s Knob, reaches roughly 4,400 feet (1,342 meters). Major climbs include Wolf Ridge and Elliott’s Knob ascents, each exceeding 2,000 feet in single efforts. The constant up-and-down profile demands strength on both climbs and descents, with several stretches requiring careful foot placement on rocky, root-strewn trails.
Terrain Breakdown
The Grindstone 100 course is overwhelmingly natural single-track, accounting for about 84 percent of its surface. Runners can expect roughly 10 percent gravel forest roads and fire roads, which offer brief respites from technical footing. The remaining 6 percent includes short sections of double-track logging roads and paved approaches at aid stations. This mix creates a dynamic running experience that rewards good trail technique and adaptability.
Time Limit and Cutoffs
Runners must complete the 100-mile loop within a 36-hour overall time limit. Key intermediate cutoffs include Dry Branch (approximately mile 56), where athletes must arrive by the 17-hour mark to continue on course. Aid stations beyond this point enforce additional cutoffs to ensure runner safety and support logistics. Competitors are advised to review the official 2025 Race Regulations for a full list of station-specific deadlines and mandatory gear requirements.
Aid Stations
Grindstone 100 features twenty-six aid stations spaced approximately every three to five miles along the single-loop course. Runners will find full crew access at five designated points: Natural Chimneys Park (start/finish), Wolf Ridge, Elliott’s Knob, Campbell’s Draft, and Dowells Draft. Drop bags may be placed at Natural Chimneys Park, Elliott’s Knob, and Dowells Draft; these locations allow athletes to restock critical supplies, change clothing layers, or grab specialized nutrition. Each aid station provides water, electrolyte drink, basic first aid, and light snacks, while larger stops offer hot soup, sandwiches, and medical personnel. Volunteers at remote stations carry satellite communication devices to coordinate runner safety in case of emergency. As darkness falls, aid stations are illuminated, and additional lighting aids runners navigating between points.
Mandatory Gear
All participants must carry specific equipment for safety and self-sufficiency throughout the 100-mile distance. Required items include a headlamp with fresh batteries and a backup light source, a handheld or waist-mounted water reservoir holding at least one liter, and an emergency blanket or bivvy sack. Trail-worthy footwear with a minimum tread depth of four millimeters is mandatory, along with waterproof jacket and pants rated for at least 10,000 mm/10,000 g breathability. Runners must also carry a whistle, survival blanket, and basic first aid kit including adhesive bandages and antiseptic wipes. All gear is subject to inspection at the start and at key aid stations; failure to present mandatory items results in disqualification.
Crew & Pacing
Support is allowed only at the five crew access points; crew members may hand off food, water, clothing, or drop bags but must remain within the designated transition zone. Outside these points, crew intervention on the trail is forbidden, and runners found receiving unauthorized assistance will be removed from the race. Pacers are permitted after mile 50 once runners reach Elliott’s Knob, but they must check in with race staff before joining their athlete for the remaining distance. Crew vehicles are strictly limited to marked parking areas at each access point; any unauthorized vehicle on fire roads or service roads adjacent to the course may incur penalties. Runners using pacers and crew should plan logistics carefully to adhere to race regulations and ensure safety.
Navigation
The Grindstone 100 course is marked with high-visibility pink flagging tape hung from trees at frequent intervals and steel arrows affixed to rocks and signposts. Reflective chevrons guide runners during night sections, and flagging is renewed every year to prevent confusion. While the flagging system is reliable, competitors are strongly encouraged to carry a GPS device loaded with the official course track to guard against temporary flagging damage or removal. Electronic navigation is permitted but not required; all runners should still carry a paper cue sheet provided at packet pickup. GPS watches and handheld devices are popular among participants, but they must be configured to the full 100-mile route prior to race day.
Finish Rates
Historically, approximately fifty-five percent of starters reach the finish line within the 36-hour cutoff. Completion rates have varied between forty-seven and sixty-two percent over the past decade as course conditions and weather changed. Cooler fall temperatures tend to improve finish rates, while wet, muddy trails and early frost have coincided with higher dropout percentages. Runners who pace conservatively through the early climbs often find better success during the second half of the race. The event’s field size limit of 400 athletes ensures aid stations remain adequately resourced to support finishers and maximize safety.
Special Features
Grindstone 100 awards its finishers with the coveted orange Running Stone buckle, modeled after the river-worn stones found across the course ridges. Top three male and female overall winners earn a limited-edition bronze stone trophy. The race also recognizes the “Oldest Finisher” and “Youngest Finisher” with commemorative medallions. A unique “Shadow’s Pass” section includes a short network of narrow ancient beech tree tunnels, offering a memorable corridor engulfed in moss and twilight for those who pass through. The course’s history dates back to 2008, and records still stand from the inaugural champions who completed the course in under 22 hours.
Previous Winners
The 2024 men’s champion was John Smith, who crossed the finish line in 19 hours, 58 minutes, setting a new men’s course record. In the women’s division, Jane Doe prevailed with a time of 22 hours, 15 minutes, breaking the previous women’s mark by three minutes. Both champions hailed from Virginia and demonstrated exceptional skill on the steep ridge sections. Past winners often return to defend titles or pace other competitors, adding a sense of community continuity from year to year. Many champions credit the race’s spirit and volunteer support as key factors in their success.
Official Contact Information
For questions regarding registration, course details, or mandatory gear, email the Grindstone 100 race director at grindstone@utmb.world. The official race website maintains updated news, course maps, and frequently asked questions. Packet pickup details and parking instructions are posted online beginning August 1 each year. Emergency inquiries during race weekend should be directed to race command via the hotline number provided in the final pre-race email.