Bull of the Woods Trail Races Course Guide

The Full Marathon is the hardest option by a wide margin: over 7,000 feet of climbing starting from around 10,000 feet of elevation, up a hands-on-knees pitch to 12,481-foot Kachina Peak, back down the Highline and West Basin Ridges, then a second climb up Fraser Peak on the Northside Trail System before a long descending finish. Add in the thin air at that altitude and this is a genuine high-alpine test even before you account for the technical single-track. The TSV Half Marathon shares the Kachina Peak climb and descent, so it delivers a similarly punishing first half without the second peak.

The race’s own course description puts the Full Marathon at over 7,000 feet of total climbing, split across two named summits: Kachina Peak at 12,481 feet and Fraser Peak at roughly 12,163 feet. The TSV Half Marathon and Northside Half Marathon each cover one of those two peaks rather than both, so their individual gain totals land well under the marathon’s, though the race does not publish an exact figure for either half separately.

The TSV Half Marathon follows the Marathon’s first half: a climb from the ski resort up to 12,481-foot Kachina Peak, taking in the entire Wheeler Peak Wilderness Cirque (seven peaks over 12,000 feet) before a rowdy descent down the Highline and West Basin Ridges to the finish. The Northside Half Marathon instead runs the Marathon’s second half on its own, primarily tight single-track through the Northside Trail System up to 12,163-foot Fraser Peak, with fast, winding, secluded single-track on the way back down. Pick TSV Half for the bigger, more exposed alpine climb, or Northside Half for the more sheltered single-track experience.

The 10K is brand new for 2026, and it is not a warm-up. The course starts with about 1.2K on mountain roads up to the base of Lift 8, then switches to single-track for the rest of the way, packing close to 2,000 feet of elevation gain into 10 kilometers. The race organizers are explicit that this is a completely different course from their earlier-summer Up and Over 10K, so treat it as its own standalone climb rather than a repeat.

Starting around 10,000 feet and climbing past 12,000 feet on both peaks means altitude, not just distance, is working against you all day. Dehydration hits faster at elevation even in cool mountain air, so drink on a schedule rather than waiting for thirst, and keep sodium in a normal 300 to 700 mg per liter range unless the day runs unusually hot. Aim for roughly 60 to 90 grams of carbohydrate per hour on the Marathon and TSV Half, scaling down for the shorter Northside Half and 10K. Build your specific numbers with the free ultra fueling calculator before race day.

The 10K and Northside Half Marathon are reasonable entry points if you have some trail experience and want a taste of true high-alpine terrain without committing to the full Marathon’s two-summit day. The TSV Half and Full Marathon are a bigger ask: sustained climbing above 12,000 feet, hands-on-knees pitches, and real exposure to altitude effects even for fit runners coming from lower elevation. If this is your first time racing above 10,000 feet, arrive a few days early to acclimate if you can, and respect that altitude alone will slow you more than the terrain suggests on paper.