Ultra Running Hub Castro Valley, CA, United States · Saturday, April 24, 2027
Fixed Distance 50K
SPASM Lake Chabot 50 km
233 days away
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.
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 Climbing is unpublished, so this pace is a ceiling on the effort, not a measure of it.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 982 races of the same distance. Cut-off calculator →
Field size ~20 Small. Long stretches with nobody in sight.
DUV results for the 2026 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, April
Daytime high 18°C
Night low 6°C
Rainfall Mostly dry
Daylight 13 h 28 m of light
Regional 2001-2020 average for April — NASA POWER, grid elevation 233 m. Not a forecast.
The Aid Station
Course-specific beta from the community
With trail terrain, choose a shoe with moderate cushioning for optimal performance.
Gear for this race
Chosen for 50 km of trail.
- Trail Running Shoes 50 km of trail — cushioning that is still there in the last quarter.
- Race Nutrition 50 km of self-supported fuelling between aid stations.
- Hydration Vests Flask capacity for 50 km, without the bounce.
- GPS Watches Battery life first — a 50 km day outlasts most full-GPS modes.
Course Notes
The course starts at the Marina and travels around the popular Lake Chabot Reservoir and surrounding hills.
Similar races
Other 50K trail ultras, closest in distance first.