Bottom Bracket Installation Guide: BSA, PF30, and BB86 Explained

The bottom bracket (BB) is the bearing system between the crankset and the frame, and it carries every bit of force a rider puts into the pedals. Installing it incorrectly can cause creaking noises, reduced pedaling efficiency, and even damage to an expensive frame. This article systematically covers the various bottom bracket standards and how to install each one correctly.

Overview of Bottom Bracket Standards

The bottom bracket standards on the market today can be dizzying. Here are the most common ones:

Standard	Type	Shell Width	Bore Diameter	Common Brands/Frames
BSA (English)	Threaded	68/73mm	34.8mm	Shimano, most steel and aluminum frames
Italian	Threaded	70mm	34.8mm	Some Italian frames
PF30	Press-fit	68/73mm	46mm	Cannondale, some carbon frames
BB86 (PF86)	Press-fit	86.5mm	41mm	Shimano press-fit standard, most carbon road bikes
BB92	Press-fit	89.5/92mm	41mm	Common on mountain bikes
BB30	Press-fit	68/73mm	42mm	Cannondale (earlier generation)
T47	Threaded	68/86.5mm	47mm	Newer standard combining the benefits of threading

How do you confirm your bottom bracket standard? Checking the frame’s spec sheet is the most reliable method. You can also measure the width and bore diameter of the BB shell to determine it.

Tool Preparation

Threaded Bottom Brackets (BSA/Italian)

• Bottom bracket tool: The correct socket for removal/installation (e.g., Shimano Hollowtech II uses the TL-FC32)
• Torque wrench: Range covering 35-50 Nm
• Threadlock grease or anti-seize compound
• Degreaser and rags
• Thread chaser (not essential, but recommended for cleaning up threads)

Press-Fit Bottom Brackets (PF30/BB86/BB92)

• Bottom bracket press tool (dedicated or a universal press kit)
• Bottom bracket removal tool
• Bearing-specific grease
• Loctite 609 or equivalent bearing retaining compound (used in some cases)
• Degreaser and rags

Installing a BSA Threaded Bottom Bracket

BSA is the most classic and easiest-to-maintain bottom bracket standard. Here’s the process using a Shimano Hollowtech II system as an example:

Removing the Old Bottom Bracket

1. Remove the left crank arm first (loosen the pinch bolt, remove the plastic cap, use a crank puller tool)
2. Pull out the right crank (with the chainrings attached)
3. Use the appropriate tool to remove the bottom bracket cups

BSA Thread Direction (Critically Important):

Side	Removal Direction	Installation Direction	Thread Notation
Right (drive side)	Clockwise to remove	Counterclockwise to install	Left-hand thread
Left (non-drive side)	Counterclockwise to remove	Clockwise to install	Right-hand thread

Memory tip: The drive side uses reverse threading — loosening turns in the direction of pedaling. This design prevents the bottom bracket from working itself loose while riding.

Installing the New Bottom Bracket

1. Clean the threads: Thoroughly clean the threads inside the BB shell with degreaser
2. Chase the threads (recommended): Use a BB thread chaser to clean up the threads and ensure smooth engagement
3. Apply grease: Apply a generous amount of grease to the threads (this prevents creaking and makes future removal easier)
4. Install the right cup: Thread the right cup (drive side) in counterclockwise, hand-tightening first to confirm it turns smoothly
5. Torque it down: Use a torque wrench to tighten to 35-50 Nm
6. Install the left cup: Thread it in clockwise, and torque it to the same spec
7. Install the crankset: Insert the spindle from the right side, then attach the left crank arm

Crank Installation Torque Values

Component	Torque
Bottom bracket cups	35-50 Nm
Left crank pinch bolt	12-14 Nm
Chainring bolts	12-14 Nm
Pedals	35-55 Nm

Installing a Press-Fit Bottom Bracket (BB86 Example)

Installing a press-fit bottom bracket requires more skill and patience:

Removing the Old Bottom Bracket

1. Remove the crankset
2. Insert a press-fit BB removal tool from one side
3. Position the tool against the inner edge of the bearing cup on the other side
4. Tap or turn evenly to drive the bearing cup out
5. Repeat on both sides

Cleaning and Preparation

1. Clean the inner wall of the BB shell with degreaser
2. Inspect the BB shell: For carbon frames, carefully check for cracks, delamination, or wear
3. Confirm the inner wall is smooth with no leftover adhesive residue
4. Let it dry before proceeding

Installing the New Bottom Bracket

1. Apply a suitable amount of grease to the outer surface of the bearing cups (some manufacturers recommend Loctite 609 retaining compound)
2. Confirm bearing cup orientation: they’re usually marked to indicate left and right side
3. Align the bearing cup with the opening of the BB shell
4. Use a bottom bracket press tool to press it in slowly and evenly
5. Press until it’s fully seated at the bottom with no gap
6. Once both sides are installed, confirm the bearing spins smoothly

Common Press-Fit Bottom Bracket Disasters:

• Pressing in crooked: The bearing cup wasn’t aligned before pressing began, causing it to jam or damaging the frame
• Hammering it in: Uneven force can crush the bearing or damage the BB shell
• Forgetting to grease: Removal later becomes extremely difficult, sometimes requiring destructive extraction

The Creaking Problem with Press-Fit Bottom Brackets

The most notorious complaint about press-fit bottom brackets is creaking noise. Here’s how to prevent and resolve it:

Preventive Measures

• Make sure the bearing cups are fully seated during installation, with no micro-gaps
• Use quality bearing cups (Chris King, CeramicSpeed, and Wheels Manufacturing are recommended)
• Consider a threaded conversion kit (such as Wheels Manufacturing’s PressFit to Threaded conversion cups), which converts a press-fit shell to a threaded interface

Steps to Diagnose Creaking

1. Remove the bottom bracket and crankset
2. Clean all contact surfaces
3. Reapply grease
4. Re-press or re-torque
5. If the problem persists, consider switching to a threaded conversion kit

T47: The Answer for the Future?

T47 is a newer standard that combines the large bearing clearance of press-fit designs with the reliability of threaded designs. If your frame supports T47, it’s strongly recommended — installation is similar to BSA but uses a larger thread diameter, and it virtually eliminates the creaking problems associated with press-fit bottom brackets.

Post-Installation Checklist

• [ ] The crank spins smoothly with no resistance or noise
• [ ] No play when rocking the crank side to side
• [ ] All bolts are torqued to spec
• [ ] Recheck everything after a test ride

A correctly installed bottom bracket should run trouble-free for thousands of kilometers. Regular maintenance (checking every 3,000-5,000 km, or after riding in the rain) can significantly extend the bottom bracket’s service life.

Related Reading

• BB (Bottom Bracket) Fully Explained: Standards, Maintenance, and Fixing Creaks
• The Great Bicycle BB Standards Showdown: A Buying Guide to BSA, PF30, BB86, and T47
• Complete Guide to BB Bottom Bracket Removal, Installation, and Bearing Maintenance
• Bottom Bracket Maintenance and Replacement: Press-Fit vs. Threaded Removal Tools