Bicycle Derailleur Shifting Issues Due to Bent Hanger

To verify if a bent derailleur hanger is the cause of poor shifting, stand directly behind the rear wheel and observe the derailleur cage. The cage should hang perfectly vertical and parallel to the cassette cogs. If the cage appears angled inward toward the spokes or outward away from the wheel, the hanger is likely bent, leading to inconsistent shifting performance across the entire gear range.