Bicycle Derailleur Shifting Issues Due to Cable Tension

To confirm that incorrect cable tension is the cause of shifting issues, perform a test shift through the gear range while pedaling in a stand. Identify if the chain hesitates to move to larger cogs (indicating loose tension) or hangs when attempting to move to smaller cogs (indicating excessive tension). Inspect the barrel adjuster at the shifter or derailleur to ensure it is not fully threaded in or out, which would prevent further adjustment.