Born in Marin County, DeMattei grew up in San Rafael, California.[1][6][7] She first became interested in cycling while attending California State University, Chico, where she was pursuing her nursing degree.[1] She began as a recreational road cyclist before taking up mountain bike racing.[1] DeMattei was a talented climber, and almost immediately after taking up cycling, she was setting local road hillclimb records with times out of reach of most of the male competitors. She tried her hand at mountain bike racing, to even greater success, and was quickly signed to a professional contract by the Diamondback racing team.
From 1990 through 1996, DeMattei finished in the top three in the NORBA Championship Series every year but one.[1] DeMattei won the silver medal in the cross-country class at the 1994 UCI Mountain Bike World Championships in Vail, Colorado.[8]
Later life
DeMattei married former professional mountain bike racer and teammate, Dave Wiens.[1] She currently resides in Gunnison, Colorado where she works in the surgical unit of a local hospital.[2]