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Triathlon Calendar near O'Fallon 2026-2027

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Explore the top triathlons near O'Fallon for 2026-2027! We've gathered 3 exciting races in the area. Check out our detailed list below to find your next local race.

September 2026
Sep
13
Su

Millstadt Parks Biathlon

Duathlon Individual Biathlon 5 22 mi Team Biathlon - Male 5 22 mi Team Biathlon - Female 5 22 mi Team Biathlon - Co-Ed 5 22 mi
A biathlon of a 5 mile run plus a 22 mile bike ride and a separate 5K run in Millstadt on September 13, 2026, with post-race amenities and proceeds to the park fund.
December 2026
Dec
5
Sa

Castlewood Adventure Race

Multisport 8 HOUR ADVENTURE RACE - S... 5 15 5 mi 8 HOUR ADVENTURE RACE - 2... 5 15 5 mi 8 HOUR ADVENTURE RACE - 3... 5 15 5 mi 8 HOUR ADVENTURE RACE - 4... 5 15 5 mi
An 8 hour off road navigation race around St. Louis combining canoeing, mountain biking and trekking with solo and team divisions.
June 2027
Jun
1
Tu

St. Louis Triathlon

Triathlon Duathlon Aquathlon Sprint 750 m 5 km Olympic 1 mi 10 km Sprint 750 m 20 km Sprint 750 m 20 5 km
A USAT sanctioned state championship triathlon at Creve Coeur Park on June 28, 2026 featuring sprint and Olympic formats, relays, a 6K run, pre race expo and post race festival with awards and athlete amenities.
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