Bottom Bracket Service: Cartridge Type
This article will discuss the removal and installation of the common cartridge bottom brackets of the three-piece cranksets.
Most cartridge bottom brackets are held by retaining rings or cups on either side. The description below is based on the Shimano® brand of bottom bracket, but most other cartridge type bottom bracket bearing units install in a similar fashion. NOTE: Shimano® XTR BB950 bottom bracket and Dura-Ace BB-7700 bottom brackets are adjustable type bottom brackets. See Adjustable-Type Bottom Brackets.
For the External Bearing System Cranksets, such as Shimano® Hollow Tech II, or Campagnolo® Ulta-Torque bottom bracket-crankset systems, see External Bearing Crank System Service.
There are two different styles of Shimano® cartridge bottom brackets. One type has a fixed flange on the right side (drive side). The other type has a fixed flange on the left side (non-drive side). Each one uses a removable ring opposite the fixed flange. See the figure below.
There is a fairly simple test to determine if the bottom bracket bearing is worn out. Shift the chain to the inner most rear sprockets front and rear. Drop the chain off the smallest front ring, and arrange it so it will not strike the chainrings. Spin the crank while holding the bike with one hand. If you feel an obvious rumbling or grinding feeling, the bearing are wore out and the unit should be replaced. Very worn bottom brackets will actually make a grinding noise.
Bottom Bracket Removal
Begin bearing service by first removing both cranks. See Three Piece Crank Removal and Installation.
Some bottom bracket models use a steel or aluminum ring on one side and a plastic ring opposite. On these models, remove the metal side first regardless of left or right side. Otherwise, insert BBT-22 or other tool fully into splines on left side. Some brands use an eight notched ring, which will accept the BBT-18. Use care to hold either tool firmly in place. Remove the non-drive side by turning counter-clockwise. For some models, this removes the ring; in some models, this pulls the cartridge body out.
Insert the tool fully into the splines on the opposite side. For non-drive side, remove by turning counter-clockwise. For drive side, turn clockwise to remove.
The spline system used on many cartridge bottom bracket is very shallow. If the spindle is hollow, use the rear hub skewer to hold the tool firmly in place. When using this technique to remove the spindle, break the threads free, then loosen the skewer as the cup comes out.
THREADING NOTE: Most modern bikes use an ISO thread standard for the bottom bracket. The left side thread is a right-hand direction thread, which tightens clockwise and removes counter-clockwise. This standard is also called English or BSC. The right side (drive side) thread is a left-hand thread, which tightens counter-clockwise and remove clockwise. There are some exceptions to the ISO. Bikes made in Italy may use “Italian” threading, with both drive and non-drive sides right hand thread. There may be markings such as “36 x 24” on the cups. Older bikes from France may have right hand threads on both sides (35mm x 1mm). It is especially recommended for bikes with a right-hand thread for the drive side to use a thread locker in addition to full torque. See more on thread preparation and thread lockers in Basic Thread Concepts.
Below is an image of the common ISO threaded cups. Note the threads of the left-threaded (drive side) cup slope upward to the left. Threads of the right-threaded (non-drive) cup slope upward to the right.
Cup direction for non-drive (left side of bike) and drive side (right side of bike) are shown below for the common ISO/English bottom brackets.
It can occur that the cup becomes seized in the frame. Be sure to double check thread direction when in doubt. The common 20-tooth internal spline cup has shallow splines for tool engagement. Use a long bolt to secure the BBT-22 to the cup. A skewer can be used if the spindle is hollow. Use a bench vise to hold the tool. The frame become the lever. Again, double check thread direction before turning. Soak threads with a penetrating fluid before attempting removal.
Cup and Lockring Type
There are several variations on the cartridge bottom bracket system. One type uses cups and separate lockrings on both side. The bearings are typically common industrial types. The cups are removed and then the bearings replaced. In the image below, the cup looks similar to the adjustable bearing types. A lockring spanner is used on the lockring, and then a spanner such as the SPA-4 is used in the cup. The cup is run up to the bearings and then the lockring is secured. There is no bearing adjustment in this system.
Bottom Bracket Installation
Begin by preparing the threads of the bottom bracket. A thread locker may be used when the frame shell is steel and the cups are either aluminum or steel lockrings. A mild thread locking compound such as Loctite® #242 that is considered “service removable” is preferred. This means that the parts are removable with normal tools, without taking extreme measures. If no thread locking compound is available, grease threads heavily or ASC-1 Anti Seize Compound. For more on thread preparation see Basic Thread Concepts.
If the bottom bracket frame shell is aluminum or titanium, use Park Tool ASC-1 Anti Seize Compound. Even if lockrings are steel, use anti-seize. Anti-seize is available at some bicycle stores, hardware stores, or automotive parts stores. Grease can be used in place of anti-seize, but anti-seize is more durable and provides better lubrication during tightening. Apply this only to the threads.
Plastic lockrings or cups need only grease on the threads. Do not use thread lockers on plastic as the chemical may cause the plastic to become brittle.
It can sometimes happen a bottom bracket can creak where the lockring or cups meet the bearing body. To prevent this, apply a thread locking compound such as Loctite #242 to the inside area of removable ring, where it meets the body. This will help prevent any creaking in the future. With plastic rings, do not apply any thread locking compound.
Look on body of cartridge for “L” and “R”. “L” goes to the left side of bike, and “R” goes to the right side of bike. For most bikes, the right side (“R”), has left-hand direction threads, thread this side by turning counter-clockwise. The left side (“L”) has right-hand direction thread, so thread this side by turning clockwise. (See THREAD NOTE on thread direction above.) Thread the cartridge body into bottom bracket by hand, being careful not to cross thread.
Snug to snug fixed flange against face of bottom bracket.
Thread in removable ring to appropriate side.
Secure removable ring to at least 360 inch pounds using torque wrench. If you are using hand wrench, and are holding the wrench 6 inches from axle, apply 60 pounds of pressure… which is tight. By securing removable ring, you are securing the other side at the same time. Removable ring pushes against fixed flange.