Where to cheer, park or avoid Ironman 70.3 Santa Rosa

Thousands of athletes are expected to swim, bike and run through Sonoma County during Ironman 70.3 Santa Rosa on Saturday.

The full Ironman - a 140.6-mile endeavor - saw 2,500 competitors in May.

As athletes get ready for the hourslong event, residents going about their daily routines also are preparing for increased traffic, road closures and detours.

Whether you're competing, cheering or avoiding it altogether, here's everything you need to know before the event.

Ironman Course

The 70.3-mile race begins at 6:30 a.m. at Lake Sonoma, according to the event's website.

After completing the 1.2-mile swim, competitors will bike 56 miles through the Russian River Valley, Dry Creek Valley and Alexander Valley to downtown Santa Rosa. The 13.1-mile run takes participants on a loop along Santa Rosa Creek Trail to Willowside Road and back.

The finish line is at Old Courthouse Square.

Maps of the course are available here. See the event schedule here.

Spectator guide

The best places to cheer are along Lake Sonoma and near Old Courthouse Square, according to the event's website. Race director

On race day, spectators can track athletes online using their bib number or last name.

Road closures, traffic and detours

The City of Santa Rosa recommends downloading WAZE, a smartphone app that provides traffic updates in real time.

Ironman Village already is under construction near Old Courthouse Square. Street closures include Courthouse Square West Road, Courthouse Square East Road, Third Street and Fourth Street.

On Saturday, portions of First Street, Santa Rosa Avenue, B Street, D Street, Seventh Street and West Ninth Street will be closed. Other parts of Santa Rosa and Windsor, such as Shiloh and Windsor roads, also will experience road closures and delays. Visit for more information.

Specific detour information for each neighborhood is available in the map below.

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