Endurance Grid lists 3 duathlons in Illinois, from September 2026 to July 2027 across 2 cities.
The lay of the land
The duathlon race calendar in Illinois is busiest in July, September, and October, with races most often in Rockford.
A duathlon is a triathlon without the swim: you run, transition to the bike, ride, then transition back and finish on foot. Two disciplines, two timed transitions, no open water — which makes it one of the most accessible ways into multisport racing.
Most US duathlons run one of two distances. A sprint is roughly a 5K run, 20K bike, and 2.5K run — short enough to finish on a first attempt. The standard, often called Olympic, doubles the front end to a 10K run, 40K bike, and 5K run. Exact distances vary by organizer.
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