Bad Bass - Castro Valley
Castro Valley, United States • 18 Jul 2026
Bad Bass - Castro Valley
Bad Bass is a race day at Lake Chabot Marina in Castro Valley, California, offering three distances: a 5K, a 10K and a half marathon. The event takes place in the San Francisco Bay Area and uses a mix of paved trails and fire roads.
Course surfaces:
- 5K: entirely on paved trails.
- 10K: about 50% paved trails and 50% fire trails.
- Half marathon: approximately 25% paved trails and 75% fire trails.
The 5K and 10K are essentially out-and-back courses, while the half marathon is a loop. All courses include rolling hills that are mostly runnable; the climb up Live Oak on the half marathon and 10K is noted as best power-hiked. Courses are marked with flour, course signs, and colored ribbons: red for the half marathon, blue for the 10K, and yellow for the 5K.
Aid stations and services are provided on course. The 5K has one aid station, the 10K three, and the half marathon three. Stations are stocked with water, sports drink, gels, pretzels, candy and similar items. Organizers recommend carrying a personal water bottle or hydration pack when more frequent access to fluids is needed. The half marathon has a 4.5 hour course time limit and intermediate cutoffs at roughly mile 4.3 and mile 8.7; participants missing cutoffs may be offered a ride back to the finish.
GPX files created with Ride With GPS are available for each course. Visit the organization's website for the most recent information.