About this event
OC MTB Limestone XC Race is a single-lap, 21-mile cross-country mountain-bike race through protected Limestone Canyon in Orange County. The current course combines fire roads and singletrack with approximately 3,765 feet of climbing, technical sections, switchbacks, and steep climbs and descents. Eight-, 11-, and 18-mile safety checkpoints are identified, and the supplied GPX is based on the 2025 route. Racing leaves Augustine Staging Area in four waves: Male Open at 8:00 AM, Female Open at 8:02, Male First Year at 8:05, and Female First Year at 8:07. The organizer also sells a Single Speed category through BikeReg. A taco lunch follows at 10:15 AM and awards begin at 10:30. The overall male and female competitions each advertise a five-place payout of $500, $300, $200, $150, and $100, for a combined $2,500 purse; class podiums receive trophies. Limestone Canyon is normally controlled-access conservation land, making this a rare sanctioned racing opportunity. Pre-riding is prohibited except during the race-morning partial-lap warmup, official wilderness access days, or docent-led activities.
At a glance
Open mountain-bike race with Open, First Year, and Single Speed entry options. All racers must be able to safely complete a technical 21-mile course with approximately 3,765 feet of climbing. The organizer publishes age-group classes but no license, membership, qualification, residency, or invitation requirement.
open
Limestone Canyon Nature Preserve - Augustine Staging Area
In person
Event links
Official 2026 event details
Live BikeReg registration
OC MTB race rules
Organizer-supplied Limestone GPX
Official Augustine directions and safety guide
OC Parks Irvine Ranch Open Space
OC Parks rules including e-bike restriction
OC MTB Races on Facebook
OutdoorSoCal event listing
Augustine Staging Area map
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