He had suffered serious head injuries after being run off the road by a sport utility vehicle in Laguna, N.M., about 50 miles west of Albuquerque, officials said.
Friends riding with him who saw the crash said they were angry at the SUV driver, who they said caused the accident, and want the public to learn from what they called a careless mistake, KOAT-TV, Albuquerque, reported.
The identity of the male driver was not made public Thursday night. Nor did authorities say whether he had been or would be charged with any crime.
Fellow cyclist Ty Bereskie said the driver was an older man who lived on the Laguna reservation. The Laguna are a Native American tribe of the Pueblo people in west-central New Mexico.
Bereskie said the driver did not stop immediately after hitting Anczarski, the Standard Speaker of Hazleton, Pa., reported.
Because the crash occurred on tribal lands, it is being handled by the U.S. Bureau of Indian Affairs.
Friends said Anczarski came up with the idea to ride bikes from Ringtown, Pa., where he lived, to California to raise money for breast cancer research.