Races
Mammoth Trailfest 50K
Mammoth Lakes trail network. Nine thousand foot ridges in July. Four thousand five hundred feet of vert when the Sierra air is thin.
50K+8,865 ft-8,862 ft10 hours8,061 ft to 10,950 fttech 8/10Checkpoints per race bookhigh altitudeSierra east sideGTWS mapJuly
Distance50K
Gain+8,865 ft
Loss-8,862 ft
Altitude8,061 ft to 10,950 ft
Technicality8/10
Air35°F to 75°F
- Start8,061 ft
- High10,950 ft
- Low8,061 ft
- Finish8,064 ft
- Mid course at mile 16, cutoff 6 hours
- Finish Mammoth at mile 31, cutoff 10 hours
Field, 2025 · 4-year sampleresults
Starters672
Finish rate96%
Median8:05
Sub-24642
Geometrycourse math
Steepest drop1,447 ft-13.6% over 2.0 mi
Time over 10k ft9%
Course records
Men3:58:52Chad Hall
Women5:03:55Clara Caspard
The cruxAltitude from the gun at 7,800 feet (near mile 33)
Course DNA
The Course
Mammoth Trailfest 50K runs 50K through Mammoth Lakes, California. +8,865 ft gain and -8,862 ft loss. Surfaces skew 90% singletrack / 10% dirt road. Altitude from the gun at 7,800 feet. High point near 10,950 ft. Low near 8,061 ft. July temps run 35°F to 75°F. The course rewards patience early and punishes rushed descents after mile 25.
The Work
Train for 8,865 feet of climbing across 50K. Back-to-back long runs on similar surfaces. Practice power-hiking grades above 15 percent. 10 hours total means limited margin: rehearse fueling every 45 to 60 minutes and downhill eccentric work weekly. Technicality 8/10. Build a block that simulates the crux near mile 33.
Kit
July in Mammoth Lakes, California: plan for 35°F to 75°F. Mandatory shell if rain is in forecast. Headlamp with spare batteries if 10 hours pushes past dark. Poles help on sustained climbs above mile 13. Vest capacity for 2 liters minimum. Shoes matched to 90% singletrack: lugs for mud, rock plate if the course turns technical after mile 25.
Race Day
Hold effort through mile 13. The field often splits on the first big climb after mile 25. Altitude from the gun at 7,800 feet near mile 33 is where time is won or lost. Walk the steep pinches. Run the flats and gentle downhills. Crew at major aids: socks, calories, ice if hot. Transitions under 5 minutes when possible. Final third is 17 miles of fatigue management. Finish with reserve for the last descent.
Results
Mammoth Trailfest 50K finish lines.
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Sources (2)
- Field stats (2025): https://ultrasignup.com/results_event.aspx?did=120194
- Course record (M): https://ultrasignup.com/results_event.aspx?did=91927