Radsportteam
He turned pro in 1995 for the Montgomery Bell Cycling team which later became the U.S. Postal Service cycling team and raced for them in the 1997, 1998, 1999, 2000 and 2001 Tour de France. Hamilton protected Lance Armstrong in the mountains, and was on Armstrong's first three Tour de France winning Postal squads and quickly grew to stardom. Hamilton acted as a scout in individual time trials, riding as hard as possible to provide time-split comparisons for Armstrong. During this time he won the 1999 Danmark Rundt and the 2000 Critérium du Dauphiné Libéré, winning stages 4 and 5.