Align Rear Derailleur Hanger

A rear derailleur hanger alignment tool is required to adjust it perfectly. However when a tool is not available it can be adjusted by pulling the derailleur with ones hand away from the cassette until the derailleur is perpendicular to the ground. The stock hanger is very soft and can be bent several times. Below we use the Park DAG-1 too to straighten the hangerl. We will remove the derailleur, then use the tool to check if it aligned properly, if it is misaligned we will use the tool to bend it back into placeand repeat until we are finished.

From geometry we know two points define a line, and three points define a plane. Our goal is to place the hanger on a parallel plane with respect to the cassette. We will use the tool to place the hanger on a parallel plane as the rim. We will assume the rim and cassette are on parallel planes. We will use the DAG-1 tool to measure the distance from the rim at 3 diferent points and to bend the hanger until the distance from three points to the rim is the same.

Step #1 Check the rear derailleur hanger. Visually one can see the below hanger is bent inward toward the frame.

 

Step #2 Remove rear deraillur from the hanger with an allen wrench.

 

Step #3 Picture of rear derailleur removed

 

Step #4 View of the hanger with derailleur removed.

 

Step #5 Install the DAG-1 hanger tool onto the hanger as shown

 

 

Step #6 Test the distance from the DAG-1 tool to the rim at three points. If ths distance is the same the hanger is in the proper plane and the job is done.

 

Step #7 If the distances are not the same at all points around the rim.use the tool as a lever bending the hanger to make the distances closer. Repeat this step #6 & #7 as often as needed until the distances are the same.