How to Adjust the Bottom Bracket Bearings on a Bicycle

The bottom bracket of your bicycle allows the cranks to spin in a circle so that they may turn the chain rings and propel the bicycle forward. If your bottom bracket is not set up, maintained and adjusted correctly, the cranks will not sit flush with the bearing race, causing unnecessary friction in the bottom bracket and a hard-to-turn crank. Keep your bicycle's drive train working correctly by inspecting and adjusting the bottom bracket.

Things You'll Need

  • Bottom bracket race wrench
  • Bottom bracket lock ring wrench
Show More

Instructions

    • 1

      Set the bicycle in a work stand or upside down on its handlebars and seat so that it will not fall over while it is being worked on.

    • 2

      Loosen the bottom bracket lock-nut with an adjustable open-ended wrench. Be careful. Some bottom bracket lock-nuts are reverse-threaded, so if the nut doesn't want to move, try spinning it the other direction.

    • 3

      Loosen the bottom bracket bearing race with the bottom bracket tools until it separates from the bicycle frame. Hold this race in place with one hand while turning the cranks to the left with the other. When the bottom bracket bearing race makes contact with the frame, stop turning the cranks and allow them to spin freely. Be sure there is no play in the bottom bracket.

    • 4

      Hold the bearing race in place while you tighten the bottom bracket lock-nut against it. Be sure that the race doesn't get any tighter against the frame during this process or the cranks may become very hard to turn.

    • 5

      Take the bike for a test ride. Feel for any play or looseness in the cranks and pedals. If all is tight, feels secure and spins smoothly, you are ready to ride.