Learn the diagnostic sequence behind indexing and derailleur adjustment before turning limit screws at random.
Diagnose before adjusting
Poor shifting can come from cable tension, contamination, worn drivetrain parts, a bent hanger, incompatible components, or setup errors. Do not treat every shifting problem as an indexing problem.
Work from observation rather than assumption: identify the exact component or symptom, consult the relevant specification when one exists, and verify the result before returning the bicycle to normal use.
Indexing vs limits
Indexing controls how the derailleur lines up across gears during normal shifting. Limit screws constrain travel at the ends of the range. Randomly turning limit screws can create a worse—and potentially damaging—problem.
Work from observation rather than assumption: identify the exact component or symptom, consult the relevant specification when one exists, and verify the result before returning the bicycle to normal use.
Use a sequence
Check wheel seating and obvious damage, inspect the drivetrain, confirm cable or electronic system condition, then make small controlled adjustments according to the component maker's procedure.
Work from observation rather than assumption: identify the exact component or symptom, consult the relevant specification when one exists, and verify the result before returning the bicycle to normal use.
Escalate when alignment is suspect
A bent derailleur hanger or damaged derailleur often requires measurement, replacement, or specialist tools. If the derailleur can move toward the spokes, stop and resolve the cause before riding.
Work from observation rather than assumption: identify the exact component or symptom, consult the relevant specification when one exists, and verify the result before returning the bicycle to normal use.