How to Adjust a Bike Derailer

Adjust a bike derailer to properly move the chain from sprocket to sprocket. A mountain bike or English style racing bicycle may have 10, 12 or 15 speeds that are geared by a combination of front and rear sprockets. The derailers are chain guides that control shifting. The derailer needs adjustment if the chain cannot reach all the available sprockets by shifting.

Things You'll Need

  • Open end wrench set Pliers
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Instructions

  1. How to Adjust a Bike Derailer

    • 1

      Ride the bike and shift both derailer levers to their full forward position. A mountain bike may shift with grips on the handlebars. Look at the front and rear sprocket assemblies to see which sprockets this shift setting places the chain on. The chain should be on the smallest sprocket of both assemblies.

    • 2

      Release the front derailer cable. Loosen the nut holding the cable on the front derailer with an open end wrench. The cable will either be threaded through a hole in the bolt, or wrapped around the bolt head.

    • 3

      Align the front derailer. Place the chain over the smallest front sprocket, if it's not there already. Set the right side of the derailer, from the rider's perspective, against the chain as it rests on the small sprocket.

    • 4

      Secure the adjustment. Pull the derailer cable wire as tightly as possible with pliers and tighten the nut to hold this tensioned position.

    • 5

      Adjust the rear derailer. Flip the bicycle and rest it on its seat and handlebars to access the rear derailer cable bolt. Loosen the nut holding the cable with an open end wrench. Align the tiny sprockets of the rear derailer with the smallest gear sprocket. Place the chain on that sprocket. Pull the cable tightly with pliers and hold the tension while securing the nut.

    • 6

      Check your adjustments. Ride the bike and shift both gear levers. The shifters should be able to set the chain on any of the front or rear sprockets.