How to Replace a Bike Gear

A mountain bike's front gears, or "chain rings," often suffer damage, where from flying rocks, or impacts with curbs and tree stumps. The gears' teeth can also get bent from too much torque, or worn down from dirt and general usage. The biggest gear is absorbs most of the damage, and often needs replacing the most. By removing only four bolts, you can take the big gear off your bike, put the new one back on and be back riding in about 30 minutes.

Things You'll Need

  • 5-mm hex key
  • Locktight solution
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Instructions

    • 1

      Get on the bike. Pedal forward and shift it into the smallest gear on the front. Lean the bike against the wall.

    • 2

      Locate four bolts on the outside of the biggest gear on the front of the bike. The four bolts will be just outside the bikes pedal axle, or "bottom bracket" on the arms of the gear.

    • 3

      Hold the pedal with your left hand for leverage. Remove the four bolts with the 5-mm hex key. Pull on the gear. It should come loose or fall off by itself. Pass the gear down along the crank arm and off the crank over the pedal. The pedal should pass through the center of the gear.

    • 4

      Place the new gear on. Stick the pedal through the center of the gear. Thread the gear up the crank arm and into place on the middle gear.

    • 5

      Place a small amount of Locktight on the bolt threads. Insert the four bolts through the matching holes in the large gear into the second gear. Tighten securely with the 5-mm hex key.