Designed to control the alignment of rear derailleur hanger and solve most
derailleur shifting problems, especially those with index shifting systems.
Directly threads into the derailleur hanger and the gauge bar hold a gauge that marks the distance to the rim.
Rotates the gauge with the wheel to the 3, 6, 9, and 12 o’clock positions to check potential
differences in measurements.
Apply pressure to the tool’s arm to the derailleur hanger to check the results instantly