Friedrich impressed the Rockies with his physical conditioning this winter after a difficult year at Double-A Tulsa in 2011 (6-10, 5.00 ERA). He will get regular work in Minor League games.
LeMahieu, 23, hit .250 in 37 games for the Cubs last season. The Rockies acquired LeMahieu and outfielder Tyler Colvin from the Cubs for third baseman Ian Stewart and pitcher Casey Weathers in December.
The Rockies will keep LeMahieu in Major League camp, however.
The Rockies also reassigned right-handed pitchers Rob Scahill and Josh Sullivan to Minor League camp.
In addition, the Rockies outrighted outfielder Jamie Hoffmann off the 40-man Major League roster. The 27-year-old, who appeared in two games with the Dodgers last year, elected to become a free agent.
The Rockies have 44 players in camp and 38 on their 40-man roster.