About Thaiwoo 50
Thaiwoo 50 is the 51.0km ultra trail at Nike ACG 2025 Ultra-Trail Chongli 2025 (Chongli, China). The race starts on July 11, 2025.
Race strategy
Hold a steady pace and save energy for every section.
- 315m descent. Go easy, save your quads.
- Steep 25% wall. Control your pace and stay focused.
- Long race. Control your HR and effort. Early mistakes cost the most.
- Ease into the early runnable section, save your quads on the descents until 23.1km, then run your race pace, and go all out on the final descent from 42.4km.
- Start · 0.0km–1.5km · Race-day nerves push your heart rate up: don't follow the crowd, find your own rhythm.
- Settle in · 1.5km–20.7km · Descent of 315m averaging 13%, climb of 460m, high point 2035m. Plus 1 more descent. Ease in: hold back more than feels necessary. The race is still ahead. Climb by heart rate or breathing, not pace. This descent is hard on the legs: short steps, stay in control, poles if you have them. Running pays off here: run wherever you can.
- Work · 20.7km–25.9km · Descent of 334m averaging 14%. Plus 1 more climb. This is where the race is built: steady, solid effort. Climb by heart rate or breathing, not pace. This descent is hard on the legs: short steps, stay in control, poles if you have them.
- Fade · 25.9km–42.4km · Plus 2 more climbs and 2 descents. Your energy fades, and that's normal: hold a steady effort and stop counting the miles. Climb by heart rate or breathing, not pace. Hike the steepest pitches. Your heart rate drifts down on its own: don't chase your early-race numbers, go by feel.
- Home · 42.4km–49.5km · Descent of 402m averaging 6%. No heroics: settle back into your own effort and hold it to the line. Long descent: keep it even and let go only near the end.
Course
The course climbs 2332m+. With 46m/km of climbing, this is a true mountain course with sustained climbs and descents. By gradient, 40% of the distance is uphill, 45% downhill and 15% flat. The longest climb runs 4.3km at an average 10.7% grade (460m of vertical). The longest descent runs 10.9km at an average 7.4% grade (801m of vertical). The steepest climb averages 34.1% over 0.4km. The steepest descent drops at 32.7% over 0.4km. Surface: 28% trail, 25% road, and 19% smooth. Flat-equivalent effort: 73.3 FlatKM.
Poles
Poles bring little benefit here: only about 8.4km of pole-friendly terrain.
Quad damage
Quad damage risk is moderate (index 35 of 100), with 42% of the load in the first half: 2 descents deserve a plan and a couple of downhill sessions before race day.
- Ease into the early runnable section, save your quads on the descents until 23.1km, then run your race pace, and go all out on the final descent from 42.4km.
- #1 · 6.6–9.0 km · 315 m D−, -12.9% · 40.5 km ahead → control
- #2 · 20.7–23.1 km · 334 m D−, -13.8% · 26.4 km ahead → control
- 25.9–28.9 km · 311 m D−, -10.4% · 20.6 km ahead → your pace
- 30.2–41.1 km · 801 m D−, -7.4% · 8.4 km ahead → your pace
- 42.4–49.5 km · 402 m D−, -5.7% · 0.0 km ahead → even, let go at the end
Weather
On race day, start temperatures have historically ranged from 17°C to 25°C, with around 21°C at the highest point; the chance of precipitation is about 49%.
Results
2,115 finishers completed the 2025 edition. Men's winner: Biao Yu (China) in 5:03:04. Women's winner: Linlin Yang (China) in 5:48:24.
This page has the full results and splits, a pacing and nutrition planner, a gradient matrix, an interactive elevation profile and historical weather for Thaiwoo 50.
