Marine on St Croix, MN, United States · Saturday, September 26, 2026

Fixed Distance 50K

OBrien 50 km Race

10 days to go

50 km Distance

not publishedn/a Climbing

2.5 est Grit · Entry level

Calculated from 50 km alone — the organiser has not published an elevation profile. Read 2.5 as a floor, not a verdict.

45.1987° N, 92.7697° W© OpenFreeMap © OpenMapTiles Data from OpenStreetMap

What the course asks

Time limit 8 hours 9:36 min/km average. Comfortable. Room to walk the climbs and stop at aid. Climbing is unpublished, so this pace is a ceiling on the effort, not a measure of it. Tighter than 89% of 50K races. Measured against 1007 races of the same distance. Cut-off calculator →

Field size ~37 Small. Long stretches with nobody in sight.

DUV results for the 2025 edition (50km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

Typical conditions, September

Daytime high 22°C

Night low 10°C

Rainfall Showers likely

Daylight 12 h 02 m of light

Regional 2001-2020 average for September — NASA POWER, grid elevation 318 m. Not a forecast.

The Aid Station

Course-specific beta from the community

👟 gear

With trail terrain, choose a shoe with moderate cushioning for optimal performance.

By UltraHub Expert

Gear for this race

Chosen for 50 km of trail.

Trail Running Shoes50 km of trail — cushioning that is still there in the last quarter.
Race Nutrition50 km of self-supported fuelling between aid stations.
Hydration VestsFlask capacity for 50 km, without the bounce.
GPS WatchesBattery life first — a 50 km day outlasts most full-GPS modes.

Adidas

Terrex Agravic Speed Ultra

★★★★★ 4.5

Salomon

Sense Ride 5

RunRepeat found the Salomon Sense Ride 5 to have immaculate lockdown and a smooth and stable ride, making it confident on moderate trails and steep downhills. I…

★★★★★ 4.5

Skratch Labs

Sport Hydration Mix

Clean electrolyte drink mix with real fruit flavor. Low sugar.

$20 ★★★★★ 4.5

Nathan

VaporKrar 12L

12L race vest co-designed with ultra champion Rob Krar, with insulated bladder pocket.

$170 ★★★★★ 4.6

Suunto

Vertical

Titanium GPS watch with solar charging, offline maps, and 140-hour GPS battery.

$630 ★★★★★ 4.5

All gear guides →

Course Notes

50k course will run the 10 mile course 3 times with one mile added at the end. Course is mainly a wide grass trail with rolling hills. The hills will add up over the 3 loops.

Similar races

Other 50K trail ultras, closest in distance first.