Sean O'Brien 100K

JAN

31

2026

A multi-distance trail running event on January 31, 2026 in Calabasas, California, offering 100K, 50 mile, 50K, marathon, and 30K options; the 100K is a Western States 100 qualifier.

Sat 31 Jan 2026

Calabasas, California

Website Registration

100 kilometers 50 miles 50 kilometers 26 miles 30 kilometers

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Sean O'Brien 100K/50M/50K/26.2/30K : Calabasas, CA

The event takes place on Saturday, January 31, 2026, in Calabasas, California, with a listed venue address of 1925 Las Virgenes Road. It is organized as a multi-distance trail running event offering several race lengths on the same day.

The distances offered are:

100K
50 Miler
50K
Marathon (26.2)
30K

The 100K distance is designated as a 2026 Western States 100 qualification race. Registration for the event closed on Wednesday, December 31, 2025 at 7:00 PM local time.

Information presented for the event indicates trail views and specific mile-view locations are part of the course presentation. The event page lists related resources such as directions and entrant information. Details about start times, aid stations, course profile, and participant requirements are not provided here. Visit the organization's website for the most recent information.

100 km

100k

50 mi

50 Miler

50 km

50k

26 mi

Marathon

30 km

30k