Introduction

Bottom bracket broken and can't ride your bike? This guide will walk you through how to remove the bottom bracket, how to grease the threads of the new bottom bracket, and then how to reinstall the bottom bracket. This instruction manual is specific to square taper bottom brackets.

Flip the bike so that it is resting on the handle bars and seat.
  • Flip the bike so that it is resting on the handle bars and seat.

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Take out the bolts on the base of the crank using an allen wrench that fits the bolt. Do this to both sides. Set the bolts aside. Do this to both sides. Set the bolts aside.
  • Take out the bolts on the base of the crank using an allen wrench that fits the bolt.

  • Do this to both sides. Set the bolts aside.

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Screw the crank puller into the place where the bolts used to be. Tighten the crank puller until it pulls the crank off the bike. Repeat for the other side.
  • Screw the crank puller into the place where the bolts used to be.

  • Tighten the crank puller until it pulls the crank off the bike.

  • Repeat for the other side.

  • Set aside the cranks, keeping track of which side each one goes on.

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Go to the side that does not have the drive train. This side must be completed first! Insert the bottom bracket tool into the bottom bracket. Use the tool to turn the bottom bracket counter clock wise. It will be difficult to turn, but enough force will get it to turn.
  • Go to the side that does not have the drive train. This side must be completed first!

  • Insert the bottom bracket tool into the bottom bracket. Use the tool to turn the bottom bracket counter clock wise. It will be difficult to turn, but enough force will get it to turn.

  • Completely remove the small side of the bottom bracket.

  • Repeat for the side with the drive train, except turn the bottom bracket tool clockwise this time.

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Pull out the damaged bottom bracket from the drive train side.
  • Pull out the damaged bottom bracket from the drive train side.

  • Discard the broken bottom bracket.

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Get the new bottom bracket. Notice the left (L) and right (R) markers on the part. This will help guide you when inserting the part.
  • Get the new bottom bracket.

    • Notice the left (L) and right (R) markers on the part. This will help guide you when inserting the part.

  • Grease both parts of the threads using the paint brush. Apply enough grease so that the threads are evenly coated.

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Insert the bottom bracket from the drive side of the bike with the larger side facing your hand. Gently screw in the second set of threads on  the other side with your fingers. Gently screw in the second set of threads on  the other side with your fingers.
  • Insert the bottom bracket from the drive side of the bike with the larger side facing your hand.

  • Gently screw in the second set of threads on the other side with your fingers.

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Use the bottom bracket tool to screw in the larger side (drive side) of the bottom bracket. Make sure to screw it in counter clock wise. Screw the bottom bracket in all the way, but make sure not to tighten it down.
  • Use the bottom bracket tool to screw in the larger side (drive side) of the bottom bracket. Make sure to screw it in counter clock wise.

  • Screw the bottom bracket in all the way, but make sure not to tighten it down.

  • Repeat for the smaller side, except screw the bottom bracket in clock wise.

  • Tighten both sides down with the bottom bracket tool.

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Put the cranks back on their corresponding sides. Make sure the chain goes back around the chain ring.
  • Put the cranks back on their corresponding sides.

    • Make sure the chain goes back around the chain ring.

  • Put the bolts back through and tighten them into place with the allen wrench used earlier.

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Rotate the pedals with your hands to check that the bottom bracket is rotating smoothly and not catching.
  • Rotate the pedals with your hands to check that the bottom bracket is rotating smoothly and not catching.

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Conclusion

Congratulations! You are finished and can ride your bike again!

One other person completed this guide.

Kaitlin Brenneman

Member since: 09/29/2015

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1 Guide authored

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Cal Poly, Team 10-6, Green Fall 2015 Member of Cal Poly, Team 10-6, Green Fall 2015

CPSU-GREEN-F15S10G6

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