The cruxGrand Col Ferret (2,537 m) and Col du Montets (near mile 65)
Course DNA
The Course
Ultra Trail Du Mont-Blanc (UTMB) runs 100 mi through Chamonix, France. +33,639 ft gain and -33,636 ft loss. Surfaces skew 70% trail / 20% jeep / 10% paved. Grand Col Ferret (2,537 m) and Col du Montets. High point near 8,435 ft. Low near 2,641 ft. August temps run 28°F to 85°F. The course rewards patience early and punishes rushed descents after mile 50.
The Work
Train for 33,639 feet of climbing across 100 mi. Back-to-back long runs on trail. Practice power-hiking grades above 15 percent. 46:30 total means limited margin: rehearse fueling every 45 to 60 minutes and downhill eccentric work weekly. Technicality 6/10. Build a block that simulates the crux near mile 65.
Kit
August in Chamonix, France: plan for 28°F to 85°F. Mandatory shell if rain is in forecast. Headlamp with spare batteries if 46:30 pushes past dark. Poles help on sustained climbs above mile 25. Vest capacity for 2 liters minimum. Shoes matched to 70% trail: lugs for mud, rock plate if the course turns technical after mile 50.
Race Day
Hold effort through mile 25. The field often splits on the first big climb after mile 50. Grand Col Ferret (2,537 m) and Col du Montets near mile 65 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 33 miles of fatigue management. Finish with reserve for the last descent.