What do you adjust to fine-tune the derailleur system?

• A. High and Low limit screws
• B. The chain tensioner
• C. Barrel adjusters mounted on either the shifter or where the cable passes through to the rear derailleur
• D. The wheel axle alignment

Answer: (C)

Fine-tuning the derailleur system is done with barrel adjusters. These small screws are located where the cable housing ends at the shifter or at the derailleur itself. Turning a barrel adjuster changes the tension in the derailleur cable in tiny increments. That tiny change nudges the derailleur slightly so the chain lines up with the correct cog, helping the shifts index properly and compensating for cable stretch or friction. If shifting is off by a notch, you adjust a little, test, and repeat until the gears line up smoothly. The other adjustments—limit screws set the end travel limits, and wheel alignment or a chain tensioner aren’t used for fine-tuning shifting.