Rigby Lake RUMBLE Triathlon 2026

At Jefferson County Lake in Rigby, Idaho, the Rigby Lake RUMBLE in July is a multi-sport race featuring calm lake swimming and very flat bike and run courses. Tri Peaks Epic Events produces the event, offering sprint and Olympic triathlon, sprint and Olympic duathlon, a 5K run, a 10K run, and a two-person sprint team option. This setup accommodates first-time triathletes, runners seeking a 5K or 10K, and athletes wanting a longer, flat challenge. The swim takes place in clean lake water, and the bike and run courses are flat enough that reviewers describe them as fast and approachable. The race was previously known as the Rigby Lake Rumble Triathlon, but its current format includes run-only and duathlon events. A unique feature is the Famous Rumble Slide, where athletes can slide into the swim to receive a bonus swag item. Reviews mention friendly organizers, helpful volunteers, good spectator support, and a relaxed race atmosphere.