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Grindstone Trail Running Festival by UTMB
167.4km167.4100km10050km5021km21

Grindstone 50K

UTMB World Series
50.0km·1550m+
September 25, 07:00 AM
Natural Chimneys Park,
United States
utmb·source

Race Pace Calculator · GPX Analyzer · Trail Finder

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Read

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Full calendar: United States
50K trail race calendar

Grindstone 50K · Race profile

Distance
50.0km
Gain
1550m+
Max
1144m
Min
405m

About Grindstone 50K

Grindstone 50K is the 50.0km trail race at Grindstone Trail Running Festival by UTMB 2027 (Natural Chimneys Park, United States). The race starts on September 25, 2027 at 07:00 AM. It starts in Natural Chimneys Park. The time limit is 9 h.

Race strategy

Run easy on the first mountain, then go all out on the second.

  • Start easy and control your HR up to 19.7km.
  • Hold your race pace up to 27.8km, but stay in control.
  • The finish is runnable. Save your legs to run it all the way.
  • Ease into the early runnable section, then run your race pace.
  • Start · 0.0km–2.0km · Race-day nerves push your heart rate up: don't follow the crowd, find your own rhythm.
  • Settle in · 2.0km–19.7km · Plus 1 more climb. Ease in: hold back more than feels necessary. The race is still ahead. Climb by heart rate or breathing, not pace. Running pays off here: run wherever you can.
  • Work · 19.7km–27.8km · Climb of 588m, high point 1146m. This is where the race is built: steady, solid effort. Climb by heart rate or breathing, not pace.
  • Fade · 27.8km–42.5km · Plus 1 more descent. Your energy fades, and that's normal: hold a steady effort and stop counting the miles. Your heart rate drifts down on its own: don't chase your early-race numbers, go by feel.
  • Home · 42.5km–51.9km · 9.4km of runnable trail. No heroics: settle back into your own effort and hold it to the line. Running pays off here: run wherever you can.

Course

The course climbs 1550m+. With 31m/km of climbing, this is a rolling, mostly runnable course. By gradient, 32% of the distance is uphill, 29% downhill and 39% flat. The longest climb runs 8.1km at an average 7.3% grade (588m of vertical). The longest descent runs 14.8km at an average 6.1% grade (899m of vertical). The steepest climb averages 29.7% over 0.3km. The steepest descent drops at 20.8% over 0.5km. Surface: 57% trail, 20% road, 13% smooth, and 10% extreme.

Summits

The course also passes close to Sand Spring Mountain (1137m).

Poles

Poles bring little benefit here: only about 3.0km of pole-friendly terrain.

Quad damage

Quad damage risk is low (index 15 of 100): a few descents worth noting, none of them decisive.

  • 27.8–42.5 km · 899 m D−, -6.1% · 9.4 km ahead → your pace
  • This page has a pacing and nutrition planner, a gradient matrix, an interactive elevation profile and historical weather for Grindstone 50K.

    Other distances of Grindstone Trail Running Festival by UTMB 2027Grindstone 100M (167km)·Grindstone 100K (100km)·Grindstone 21K (21.0km)

    Other editions of Grindstone 50K2026·2025

    Official websitegrindstone.utmb.world