Bottom Bracket Service: BB30

This article will discuss the removal and installation of BB30 cartridge bottom bracket bearings.


Getting Started

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

The BB30 is a threadless bottom bracket shell system using two pressed cartridge bearings. These bearings are replaced when they wear out. However, it is possible to lift the bearing seal while the cartridge bearings are in the shell to clean and grease bearings inside.

Begin by removing cranks, following manufacturer’s direction. Look for a one-key release on one arm. Alternatively, there may a two bolt pinch system.


Bearing Removal

Inspect inside bottom bracket shell and note bearing-stop clip. If the clip uses two ears, orient foot of tool so it does not strike the clip (Figure 1).

Insert BBT-39 through one bearing. Tilt tool and guide the foot into the shell (Figure 2).

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Figure 1. Avoid "ears" of clip with foot of tool

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Figure 2. Guide tool through one bearing and engage foot against opposite bearing

Engage plastic guide bushing into bearing (Figure 3). The guide will keep tool and foot straight as it contacts bearing on opposite side.

Use hammer such as a hammer and tap end of remover (Figure 4). Use care not to strike your hand or the frame. Typically, the bearings are a mild press fit and will remove easily. If necessary, rotate tool handle to strike a different point on the bearings.

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Figure 3. Use guide bushing to keep tool aligned

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Figure 4. Strike end of tool to remove opposite bearing

After one bearing is removed, pull tool back through remaining bearing. Place tool through open side of shell and engage plastic alignment bushing. Strike end of the remover and remove second bearing (Figure 5).

Figure 5. Reverse tool and remove second bearing


Bearing Installation

The BB30 cartridge bearings are a mild interference fit into the shell. The bearing outside diameter is 42mm. The BB30 inside diameter is intended to be 41.96mm. The actual diameter may vary slightly. Bearings are only removed when they are to be replaced.

There is a bearing stop inside bottom bracket shell. These are typically snap rings that fit inside machined groves. It is typically not necessary to remove these rings. If removal is necessary, use a small screwdriver to lift lip of ring (Figure 6). Some designs require the use of snap ring pliers (Figure 7).

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Figure 6. Remove clip only if necessary

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Figure 7. Use snap ring pliers when necessary

The BBT-30.4 tool set includes two bushings for the BB30 standard. Bushing use a headset press. To install, engage cartridge bearing onto bushing. Bushings will center and align bearings during the pressing. Install bearing, bushing and headset press into shell. Place other bushing with bearing on the remainder of the press.

Turn headset press handle until plates contact bushing, bearings, and shell. Stop and double check alignment of bearings into shell and continue to press bearings. Press until both bearings strike stops inside shell. Because bushing will rotate with bearings, it is necessary to hold shaft of headset press (Figure 9).

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Figure 8. Bearings, bushings and headset tool

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Figure 9. Press bearings fully to stops inside shell

Remove headset press and pressing bushings. Check inside shell for bearing contact at stop. Install crank according to manufacturer’s instructions.