USARunningTrail100K · 100 km / 62.1 mi30K · 30 km / 18.6 mi50K · 50 km / 31.1 mi50mi · 80.5 km / 50.0 mi

Sean O'Brien 100K/50M/50K/26.2/30K

Calabasas, California · USA

When is the next Sean O'Brien 100K/50M/50K/26.2/30K?

Sat, 30 Jan 2027

5 distances · see start times below

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Time limits and cut-offs

Some events have a finishing deadline or intermediate checkpoint cut-offs. These can vary by distance, start wave and edition.

Marathon · 2027-01-30: Not yet verified for this edition. Check the official race instructions.
30K · 2027-01-30: Not yet verified for this edition. Check the official race instructions.
50K · 2027-01-30: Not yet verified for this edition. Check the official race instructions.
50mi · 2027-01-30: Not yet verified for this edition. Check the official race instructions.
100K · 2027-01-30: Not yet verified for this edition. Check the official race instructions.

About Sean O'Brien 100K/50M/50K/26.2/30K

Sean O'Brien 100K/50M/50K/26.2/30K is a running event in Calabasas, California, United States. Recorded disciplines include 100K, 30K, 50K, 50mi. The listed surface is trail. The listed organiser is Keira Henninger Events. The next listed date is Saturday, 30 January 2027. Check the organiser's information for entry and race-day arrangements.

Dates, starts & entry

Times are local to the race. Select the entry route for your distance.

Marathon · 42.2 km / 26.2 mi
Sat, 30 Jan 2027
Start time not yet verified
Entries closed
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Sean O'Brien 100K/50M/50K/26.2/30K · Marathon · 42.2 km / 26.2 mi
2027-01-30 · Date-only reminder
Venue / race area: Calabasas, California, United States
Race website
Date-only reminder: start time to be confirmed.
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Sean O'Brien 100K/50M/50K/26.2/30K · Marathon · 42.2 km / 26.2 mi
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Date and distance list (100K, 50 Miler, 50K, 26.2, 30K) confirmed on the organiser's UltraSignup registration page for the 2027 edition (checked 2026-11-09). Local time America/Los_Angeles.
Edition source
30K · 30 km / 18.6 mi
Sat, 30 Jan 2027
Start time not yet verified
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Sean O'Brien 100K/50M/50K/26.2/30K · 30K · 30 km / 18.6 mi
2027-01-30 · Date-only reminder
Venue / race area: Calabasas, California, United States
Race website
Date-only reminder: start time to be confirmed.
Google Calendar Outlook.com Microsoft 365 Apple Calendar
Google and Outlook open a prepared event for you to save. Apple uses your private AthRecs race subscription. Download a one-off file only if you prefer to import it yourself.
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Sean O'Brien 100K/50M/50K/26.2/30K · 30K · 30 km / 18.6 mi
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Choose where to share, then select who to send it to.
Date and distance list (100K, 50 Miler, 50K, 26.2, 30K) confirmed on the organiser's UltraSignup registration page for the 2027 edition (checked 2026-11-09). Local time America/Los_Angeles.
Edition source
50K · 50 km / 31.1 mi
Sat, 30 Jan 2027
Start time not yet verified
Entries closed
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Sean O'Brien 100K/50M/50K/26.2/30K · 50K · 50 km / 31.1 mi
2027-01-30 · Date-only reminder
Venue / race area: Calabasas, California, United States
Race website
Date-only reminder: start time to be confirmed.
Google Calendar Outlook.com Microsoft 365 Apple Calendar
Google and Outlook open a prepared event for you to save. Apple uses your private AthRecs race subscription. Download a one-off file only if you prefer to import it yourself.
Share
Share this race
Sean O'Brien 100K/50M/50K/26.2/30K · 50K · 50 km / 31.1 mi
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Choose where to share, then select who to send it to.
Date and distance list (100K, 50 Miler, 50K, 26.2, 30K) confirmed on the organiser's UltraSignup registration page for the 2027 edition (checked 2026-11-09). Local time America/Los_Angeles.
Edition source
50mi · 80.5 km / 50.0 mi
Sat, 30 Jan 2027
Start time not yet verified
Entries closed
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Sean O'Brien 100K/50M/50K/26.2/30K · 50mi · 80.5 km / 50.0 mi
2027-01-30 · Date-only reminder
Venue / race area: Calabasas, California, United States
Race website
Date-only reminder: start time to be confirmed.
Google Calendar Outlook.com Microsoft 365 Apple Calendar
Google and Outlook open a prepared event for you to save. Apple uses your private AthRecs race subscription. Download a one-off file only if you prefer to import it yourself.
Share
Share this race
Sean O'Brien 100K/50M/50K/26.2/30K · 50mi · 80.5 km / 50.0 mi
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Choose where to share, then select who to send it to.
Date and distance list (100K, 50 Miler, 50K, 26.2, 30K) confirmed on the organiser's UltraSignup registration page for the 2027 edition (checked 2026-11-09). Local time America/Los_Angeles.
Edition source
100K · 100 km / 62.1 mi
Sat, 30 Jan 2027
Start time not yet verified
Entries closed
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Sean O'Brien 100K/50M/50K/26.2/30K · 100K · 100 km / 62.1 mi
2027-01-30 · Date-only reminder
Venue / race area: Calabasas, California, United States
Race website
Date-only reminder: start time to be confirmed.
Google Calendar Outlook.com Microsoft 365 Apple Calendar
Google and Outlook open a prepared event for you to save. Apple uses your private AthRecs race subscription. Download a one-off file only if you prefer to import it yourself.
Share
Share this race
Sean O'Brien 100K/50M/50K/26.2/30K · 100K · 100 km / 62.1 mi
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Choose where to share, then select who to send it to.
Date and distance list (100K, 50 Miler, 50K, 26.2, 30K) confirmed on the organiser's UltraSignup registration page for the 2027 edition (checked 2026-11-09). Local time America/Los_Angeles.
Edition source

Location & race day

Listed venue / area

Calabasas, CaliforniaUSA

Find this location on a map

Confirm the exact start line, parking and arrival instructions with the organiser. A listed town or postcode may cover a wider area.

About the race

Sean O'Brien 100K/50M/50K/26.2/30K is listed on UltraSignup for 2027 near Calabasas, California, with the following distances or formats: 100K, 50 Miler, 50K, 26.2, 30K. Organised by Keira Henninger Events.

Surface:: Trail
Organiser:: Keira Henninger Events

Race website

Entry options for

Ways to enter

Compare the listed booking routes. Verified links show when they were checked.

Sat, 30 Jan 2027

Official race entry

Official entry

Closed

Recorded Mon, 9 Nov 2026

Check provider

Third-party prices, booking fees, allocations and refund terms can differ. Confirm the final details with the provider before paying.

Race questions

When is the next event?

The next listed date for Sean O'Brien 100K/50M/50K/26.2/30K is 30 January 2027.

Where is it held?

Sean O'Brien 100K/50M/50K/26.2/30K is listed in Calabasas, California, United States. Check the event's race-day instructions for the exact start location.

Which distances are listed?

The programme listed for 30 January 2027 includes Marathon, 30K, 50K, 50mi, 100K.

What time does it start?

Listed starts for 30 January 2027: Marathon: start time not yet verified; 30K: start time not yet verified; 50K: start time not yet verified; 50mi: start time not yet verified; 100K: start time not yet verified. Times are local to the race venue. Follow the start or wave assigned to your entry.