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UltraFranceVal-d'Oise

Les 40 Bosses2026

05.12 – 06.12.2026Montmorency (France)
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Pacing, fueling and crew sheet for the course you pick

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5 courses · 10–120 km · up to 4’900 m D+

5 courses

  1. 10km

    400 m D+

    avg 4%

    Trail

    06.12.

    No index

  2. 20km

    850 m D+

    avg 4%

    LES 40 BOSSES

    06.12.

    UTMB Index 20K

  3. 45km

    2’000 m D+

    avg 4%

    Les 40 bosses

    06.12.

    UTMB Index 50K

  4. 75km

    3’000 m D+

    avg 4%

    Trail

    05.12.

    No index

  5. 120km

    4’900 m D+

    avg 4%

    Trail

    05.12. · 2 aid stations

    No index

GPX trace not yet published.

Race plan

Plan your race from start to finish.

Pacing, aid stations and fueling timed to your effort on Les 40 Bosses, in one roadbook.

Includes this race's official aid stations and cutoff times.

Build your race plan →

The race

A trail race in the Montmorency forest, featuring the hardest trail in the Ile de France region and a UTMB 100M Qualifier.

Where to stay

Find a place to stay near Montmorency for the race.

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