August 2, 2026 · Boulder, Colorado, USA
140.6 mi (226 km)TriathlonFull Iron
Ironman Boulder
Altitude. Heat. Grit.
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Altitude. Heat. Grit.Course intelligence
Know the course before you race it.
Terrain
Boulder Reservoir swim, rolling to hilly bike through Hygiene and Lyons, two-loop run on the Boulder Creek Path.
Conditions
Race at 5,300 ft elevation. August temperatures reach 85–95°F by midday. Altitude reduces carb oxidation efficiency slightly for non-acclimatized athletes.
Aid Stations
Bike aid every 10 miles; run aid every mile. Gatorade Endurance on course.
Key Challenge
Altitude accelerates dehydration and suppresses appetite — two things that combine to push athletes into a caloric hole by mile 80 on the bike.
Nutrition answers for Ironman Boulder.
Does altitude change my carb targets at Boulder?
How do I handle the heat at Boulder?
Should I arrive early to acclimatize for Boulder?
What's the key nutrition mistake at Boulder?
Are there any nutrition-specific tips for the Boulder run?
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