By Brad Quartuccio
When it comes to rear derailleur performance, alignment is key. Cassette cogs are barely more than half the width of a chain apart from one another—preventing chain jumps across cogs under power and maintaining proper indexed shifting requires that the derailleur pulleys remain in perfect alignment with the cogs. No amount of barrel adjustment and limit screw fiddling will correct for a misaligned derailleur hanger—any shop worth their service tag knows that the first step in most any derailleur adjustment is checking the derailleur hanger alignment.
Derailleur hangers are commonly bent inward from laying the bike down on the driveside, or twisted from a horribly missed shift or debris caught in the drivetrain. Modern replaceable hangers common on aluminum and carbon frame can be “soft” and easily bent and in some cases hard to align properly given the flex between them and the frame. Some,