The San Francisco Triathlon at Alcatraz will bring athletes to the city’s northern and western edges Sunday to swim, bike and run in an hours-long race. It also will close roads and disrupt Muni service in the Richmond and Sunset districts, the Presidio and the Marina.

Racers will start at 7 a.m., swimming 1.2 miles from a boat in San Francisco Bay to the Marina Green. From there, they will mount bicycles for a 25-mile course through the Presidio and Lincoln Park, west on Clement Street and down Point Lobos Avenue past the Cliff House to the Great Highway.

Racers will bike along the entire Great Highway to its intersection with Skyline Boulevard at Lake Merced, where they will loop back along the Great Highway to Golden Gate Park for an out-and-back spur. In the park they will pedal along Martin Luther King Jr. Drive, Transverse Drive and a portion of John F. Kennedy Drive near Stow Lake, before returning through the park, heading back north and completing the bicycle leg of the race at the Marina Green. From there, racers will run through the Presidio including Baker Beach and up the beach’s 400-step sand ladder, looping back to the finish line at the Marina Green.

Streets along the triathlon course will be closed from 7 a.m. to 11 a.m. Sunday. Muni lines 18, 23, 29 and 38 will be affected.

For more information about traffic and Muni effects, visit the San Francisco Municipal Transportation Agency website.