How to Install, Adjust, and Maintain the SM-BB93 Bottom Bracket

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The Shimano SM-BB93 [paid link] is a lightweight, high-performance bottom bracket designed for Hollowtech II cranksets. It is an essential component in Shimano’s road and mountain bike drivetrains, offering smooth rotation and durability. Proper installation, adjustment, and maintenance are crucial for optimal performance and longevity.

This guide covers everything you need to know about the Shimano SM-BB93 [paid link], from installing it correctly to maintaining it for long-term reliability.

Tools Required

To install and maintain the SM-BB93, you will need the following tools:

  • Shimano Hollowtech II bottom bracket tool [paid link] (e.g., TL-FC24 or TL-FC25)
  • 5mm and 8mm Allen wrenches [paid link]
  • Torque wrench [paid link] (with Nm settings)
  • Grease (Shimano anti-seize recommended)
  • Isopropyl alcohol and a clean rag (for cleaning surfaces)

Step-by-Step Installation of the SM-BB93

Proper installation ensures smooth performance and extends the lifespan of your bottom bracket. Follow these steps carefully:

1. Prepare the Bottom Bracket Shell

  • Remove the old bottom bracket (if applicable) using the Hollowtech II tool.
  • Clean the bottom bracket shell with isopropyl alcohol to remove dirt and grease.
  • Inspect the shell for any damage or debris.

2. Grease the Threads

  • Apply a thin layer of Shimano anti-seize grease to the bottom bracket shell threads.
  • This prevents corrosion and makes future removal easier.

3. Install the Bottom Bracket Cups

  • Identify the right and left cups (marked with L and R).
  • Thread the right-side cup (drive side) clockwise into the shell and tighten it using the bottom bracket tool [paid link].
  • Thread the left-side cup counterclockwise and tighten.
  • Use a torque wrench [paid link] to secure both cups to Shimano’s recommended 35-50 Nm torque.

4. Install the Crankset

  • Slide the crank spindle through the bottom bracket.
  • Attach the left crank arm using the pinch bolts and torque it to 12-14 Nm.
  • Secure the preload cap using a preload tool, then tighten the pinch bolts.

5. Final Check

  • Rotate the cranks to ensure smooth movement.
  • Check for any play by wiggling the cranks laterally. If there’s play, readjust the preload cap.

Adjusting the SM-BB93 Bottom Bracket

The SM-BB93 is designed to be self-adjusting through the preload cap on the crank spindle. However, if you notice creaks, play, or stiffness, follow these adjustment steps:

1. Checking for Play

  • Hold the crank arms and move them side to side.
  • If there’s noticeable play, the preload needs to be adjusted.

2. Adjusting Preload

  • Loosen the pinch bolts on the left crank arm.
  • Use a Hollowtech II preload cap tool to turn the preload cap clockwise until there’s no play.
  • Be careful not to overtighten, as this can cause excessive friction.

3. Retighten the Pinch Bolts

  • Secure the pinch bolts in an alternating pattern to 12-14 Nm.

Maintenance Tips for the SM-BB93

Regular maintenance extends the life of the SM-BB93 and keeps your drivetrain running smoothly. Here’s how to take care of it:

1. Cleaning the Bottom Bracket

  • Every 3-6 months, remove the crankset and wipe the bottom bracket area.
  • Use isopropyl alcohol and a clean rag to remove dirt buildup.
  • Avoid using high-pressure water as it can force contaminants into the bearings.

2. Lubrication and Greasing

  • Apply Shimano anti-seize grease to the bottom bracket threads during reassembly.
  • For wet conditions, consider a water-resistant grease for better protection.

3. Checking for Wear

  • Spin the cranks and listen for grinding or resistance.
  • If the bottom bracket feels rough, the bearings may be worn out.
  • Replace the SM-BB93 when you notice excessive play or roughness.

Troubleshooting Common SM-BB93 Issues

Even with proper installation, some issues may arise. Here’s how to fix them:

1. Creaking Bottom Bracket

Possible Causes:

  • Loose bottom bracket cups.
  • Dirty or dry threads.
  • Worn-out bearings.

Solution:

  • Remove the bottom bracket, clean the threads, and reapply grease.
  • Retighten the cups to the proper torque.
  • If the noise persists, the bearings may be worn and require replacement.

2. Bottom Bracket Play

Possible Causes:

  • Loose preload cap.
  • Worn-out bearings.

Solution:

  • Adjust the preload cap and retighten the crank arm pinch bolts.
  • If play remains, inspect for bearing wear.

Conclusion

The Shimano SM-BB93 is a high-performance bottom bracket designed for Hollowtech II cranksets. Proper installation, adjustment, and maintenance will keep it running smoothly and extend its lifespan. By following this guide, you can ensure a hassle-free setup and prevent common issues such as creaking, play, and premature wear.

For more advanced guides on bottom bracket maintenance and compatibility, check out our other articles on Shimano Hollowtech II setups.