Ensure your shifter and derailleur (Gear) are correctly adjusted. When you first assemble your bike, your derailleur may need tuning if you hear any noise while shifting, if it is not shifting smoothly, or if the chain shifts past the largest or smallest cog.

While adjusting your derailleur is best done by a mechanic, it can be accomplished by following a helpful video.

Tools You'll Need:

• Allen wrenches (usually 5mm and possibly others)
• Phillips screwdriver

Step-by-Step Guide:

1. Shift to the Smallest Cog: Ensure your bike is on a bike stand or flipped upside down. Shift the rear derailleur into the smallest cog on the cassette (the hardest gear).

2. Check the Limit Screws: ( The limit screw is unlikely to be affected during shipping. In most cases, step 4 will resolve the issue. ) 

   • "H" Screw (High Gear Limit): Locate the "H" screw on the derailleur body. Turn it until the upper jockey wheel (the one closer to the cassette) aligns directly under the smallest cog. The chain should not be able to shift past this point into the spokes.
   • "L" Screw (Low Gear Limit): Locate the "L" screw. Turn it until the upper jockey wheel aligns directly under the largest cog (the easiest gear). The chain should not be able to shift past this point and fall off the cassette.

3. Adjust Cable Tension: (Usually, you don't need to perform this step. Let the bike technician handle it if necessary)

   • Loosen the Cable Bolt: Find the bolt that secures the derailleur cable to the derailleur body and loosen it.
   • Pull the Cable Taut: Use a cable puller or pliers to pull the cable tight, removing any slack.
   • Tighten the Cable Bolt: While holding the cable taut, retighten the cable bolt.

4. Fine-Tune with the Barrel Adjuster:

   • Shift Up One Gear: Shift the shifter up one gear, and pedal to allow the chain to move.
   • Observe the Shifting: If the chain struggles to move up, turn the barrel adjuster (located where the cable enters the shifter) counterclockwise (outwards) to reduce cable tension. If it shifts too easily and makes a rattling sound, turn the barrel adjuster clockwise (inwards) to increase tension.
   • Repeat: Continue shifting through the gears, making small adjustments to the barrel adjuster until each shift is smooth and precise.

Troubleshooting:

• If the Chain Doesn't Shift Up: Decrease cable tension with the barrel adjuster.
• If the Chain Doesn't Shift Down: Increase cable tension with the barrel adjuster.
• If the Chain Falls Off the Cassette (Either Side): Adjust the corresponding limit screw ("H" or "L").

Important Tips:

• Clean and lubricate the chain regularly to optimize shifting performance.
• If you're having trouble aligning the derailleur or resolving shifting issues, it's always a good idea to consult a professional bike mechanic.

It is normal to need to adjust your derailleur again after logging some miles on the bike as things settle. including the spring and cable tension involved in shifting.