The Dirty Dozen is a one-day road cycling race in Pittsburgh, Pennsylvania, held annually on the Saturday before the Halloween holiday in October.

[3][4] The Dirty Dozen was founded in 1983 by brothers Tom and Danny Chew and their friend Bob Gottlieb,[5] in an attempt to find and ride the steepest hills in Pittsburgh.

[10][11] For most of its history the race took place the Saturday after the Thanksgiving holiday in November, often under cold, wet, and especially “dirty” conditions.

In order to qualify as a finisher, riders must complete each hill in the event without losing forward progress or dismounting from the bicycle.

The course begins at the Rhododendron Shelter in Highland Park[14] and finishes at the top of Tesla Street in Hazelwood,[15] crossing approximately 87 intersections in the city and nearby suburbs.