How to Adjust the Bottom Bracket Bearings on a Bicycle

The bottom bracket is the lower center of your bicycle frame, and consequently it receives a lot of abuse. The drive train, centered on the bottom bracket, carries the weight of the rider. As you continue to ride and pedal, force can slowly loosen or wear your bottom bracket components resulting in a loose fit of the parts, which accelerates the wear of parts and can result in destruction of the cranks and bottom bracket. Adjusting the bottom bracket as it loosens or wears will help you avoid any accelerated wear or mechanical failure.

Instructions

Difficulty: Moderate

Things You’ll Need:

Clean cloth
Spanner wrench
Assorted Allen wrenches
Lockring spanner wrench
Grease

Step 1

Place your bicycle in a bike stand. If you do not have a bike stand, roll it over and let it rest on the seat and handlebars. Using an Allen wrench, loosen the bolts holding your crank arms. Hold the bike frame in one hand while applying pressure to the end of the crank arm. Rock the crank arm back and forth until it loosens from the bottom bracket. Repeat the process on the other crank arm, removing it from the bottom bracket completely.

Step 2

Loosen the lockring on the left side of the bottom bracket using a lockring spanner or bottom bracket wrench. Remove the lockring from the bottom bracket exposing the adjusting cup. Remove the adjusting cup using a spanner wrench exposing the bearings and spindle. Loosen the fixed cup on the right side using a spanner wrench. Remove the fixed cup from the bottom bracket leaving the spindle exposed.

Step 3

Remove the bearings from the bottom bracket, gently setting them on a clean cloth. Dipping your finger in grease, apply a layer across the bearings, rubbing it on the stainless steel balls. Continue to work the grease across the ball bearings until it is evenly applied. Repeat the process for the bearing on the other side.

Step 4

Place the bearing cups back into the bottom bracket with the ball bearings facing the cup, which is on the spindle. Place the fixed cup back on the right side of the bottom bracket and gently tighten it against the bearing. Place the adjusting cup on the left side of the bottom bracket and gently tighten it against the bearing. Using your hands, move the spindle from left to right. If there is any play in the spindle, tighten the fixed and adjusting cups evenly until there is no more play in the spindle. If the spindle does not move freely, loosen each side evenly until the spindle moves smoothly without any play.

Step 5

Put the lockring back onto the left side of the bottom bracket and tighten it against the adjusting cup. Place your left crank arm and crank arm bolt back onto the spindle. Tighten the bolt to the manufacturer's recommended torque specifications. Repeat the process for the other crank arm. Remove the bike from the stand or place it back on its wheels and give it a test ride.

Tips & Warnings

Periodically check your spindle as you tighten the cups by rotating the spindle, maintaining a smooth feeling rotation in the spindle

Do not over-tighten fixed or adjustable cups against bearings. They should be just tight enough to alleviate play in the spindle

Article Written By Jeremy Slaughter

Jeremy Slaughter is a tax, accounting and small business expert. After completing his master's degree in accounting at Keller Graduate School of Management, Slaughter co-founded an accounting and tax firm where writing plays a daily role.

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