How to Remove a BMX Cog

As a BMX bike is ridden, the teeth on the cogs or sprockets are slowly dulled through constant contact with the chain. Eventually the teeth become so worn the chain frequently skips off the cogs, making the bike difficult to ride. To remove the worn cog, you must detach the rear wheel from the chain and disassemble the cassette. The process seems complex at first, but it's actually straightforward, requiring only a few standard bike repair tools. Replacing a worn cog yourself will save money and give you an opportunity to get to know your bike better.

Things You'll Need

  • Adjustable wrench
  • Freewheel removal tool
  • Chain whip
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Instructions

    • 1

      Loosen the two wheel tension bolts found on either side of the rear wheel axle, using an adjustable wrench. Detach the rear wheel break cable from the tension bar, if one is present, by pinching the breaks against the wheel rim detaching the cable mounting from the tension bar using your fingers.

    • 2

      Firmly push the wheel down and away from the bike frame. Carefully pull the chain off of the sprockets and separate the wheel from the bike.

    • 3

      Unfasten the two wheel tension bolts using your fingers. Remove the axle bar from the axle.

    • 4

      Fit the freewheel removal tool through the opening found in the center of the cog. Fit the chain portion of the chain whip onto the teeth of the cog with the handle in a 3 o'clock position.

    • 5

      Fit the adjustable wrench onto the end of the freewheel removal tool with the handle pointing at a 10 o'clock position.

    • 6

      Firmly push both handles toward the ground until the cog gives way. Hold the chain whip handle still while spinning the adjustable wrench until the cog is completely unfastened.

    • 7

      Remove the tools and pull the cog off its mounting.