September 24, 2019 / Bottom Brackets

Bottom Bracket Removal & Installation: Threaded

This article will discuss how to remove and install bottom brackets used in threaded shells, including three-piece cranks, threaded "thru-spindle" external bearing cups, and bottom brackets used in T47 shells. Adjustable cup-and-cone threaded bottom brackets are reviewed in Bottom Bracket Service: Adjustable Cup-and-Cone.

1

Preliminary Info

What do I need to know how to do?
What Tools do I need?

For the two-piece crankset, there is a left and right arm, but the spindle is attached to one of the cranks. The spindle passes through the bearings in the bottom bracket shell.

Drive side crank held next to thru-spindle bottom bracket shell with external cups
Two-piece crankset with a thru-spindle bottom bracket

The common three piece crankset has left and right arms with the bearing and spindle integrated.

Drive side and non-drive side crank arms held next to bottom bracket shell on bicycle with three-piece system
Example of three-piece crankset

The common threading for bottom bracket shells is called “English.” The left-side cup is a right-hand thread direction, which tightens clockwise and removes counterclockwise. The right-side (drive-side) thread is a left-hand thread, which tightens counterclockwise and loosen clockwise.

The less common Italian has both left and right sides with right-hand threading. Both sides tighten clockwise and loosen counterclockwise. Italian threaded cups will have marking stating “36x24.”

2

Removal

Begin by removing both cranks.

Inspect the threaded cups for tool fittings. There are many different designs and tool options. See Bottom Bracket Tool Selection: Threaded and Thread-Together to determine the correct tool.

Insert the tool fully and remove the non-drive (left-side) cup by turning counterclockwise, holding the tool firmly to the cup. Remove any internal sleeve. Take note of any spacers under the cup for reassembly.

Palm of hand applying pressure to back of socket wrench with bottom bracket cup tool fitted to cup
Apply pressure to tool while removing cup

Next remove the drive (right-side) cup, turning clockwise to remove.

Closeup of external bottom bracket cup on bicycle frame with arrow designating direction of threading
Inspect for arrows indicating direction of tightening and loosening
3

Installation

Begin with thread preparation. New cups may come with dry threadlocker already applied. Install these as they come.

Another option is anti-seize such as Park Tool ASC-1. This creates a durable barrier in the threaded joint and prevents corrosion.

Still another option is a threadlocker such as Park Tool TLR-1. The liquid compound will provide lubrication when tightening before drying and hardening to seal and keep the cup in securely.

TLR-1 bottle applying threadlocker onto threads of threaded bottom bracket shell on bicycle frame
Thread retaining compound

Install any spacers as required on the right-side cup. Thread right side counterclockwise into the shell. Fully secure cup to manufacturer’s torque specifications. Typically this is between 25 to 30Nm.

Install and tighten the left-side cup, turning it clockwise to install.

Related articles

Bottom Bracket Standards and Terminology View Article

In this article
1Preliminary Info
2Removal
3Installation
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