How to Install, Adjust, and Maintain the SM-BB6800 Bottom Bracket

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The Shimano SM-BB6800 [paid link] bottom bracket is a key component in the Ultegra 6800 groupset, designed to provide a low-friction, durable interface between the crankset and the bike frame. Proper installation and maintenance of the SM-BB6800 [paid link] ensure smooth pedaling efficiency and prevent premature wear.

This guide will walk you through the correct installation, adjustment techniques, and maintenance procedures for the SM-BB6800 [paid link]. Additionally, we will cover common issues and troubleshooting steps to keep your bottom bracket running smoothly.

Tools Required

  • Bottom bracket tool [paid link] (e.g., Shimano TL-FC24 or TL-FC25)
  • Torque wrench [paid link]
  • 5mm and 10mm hex keys [paid link]
  • Grease (Shimano-approved)
  • Anti-seize compound
  • Clean rag
  • Thread locker (if necessary for metal-threaded shells)

Installation of the SM-BB6800 Bottom Bracket

1. Frame Preparation

Before installing the SM-BB6800, it is crucial to prepare the frame’s bottom bracket shell:

  • Clean the shell thoroughly with a rag to remove any dirt, old grease, or debris.
  • Inspect the shell for wear, damage, or burrs that may prevent proper installation.
  • Apply grease to the shell threads (for threaded frames) or anti-seize compound if the frame material requires it.

2. Installing the Bottom Bracket Cups

The SM-BB6800 uses a threaded BSA interface. Follow these steps for installation:

  1. Identify the left (non-drive side) and right (drive side) cups. The right-side cup is marked with an “R” and the left with an “L.”
  2. Thread the right cup (drive side) clockwise into the frame and tighten it by hand.
  3. Thread the left cup (non-drive side) counterclockwise into the frame.
  4. Use a bottom bracket tool [paid link] (Shimano TL-FC24 or TL-FC25) to tighten both cups to the manufacturer’s torque specification (typically 35–50Nm).
  5. Wipe off excess grease.

3. Installing the Crankset

  1. Slide the crankset’s spindle through the installed bottom bracket cups.
  2. Ensure the crank arms are aligned properly before tightening.
  3. Tighten the left crank arm using the preload cap and a 5mm hex key [paid link].
  4. Secure the crank arm bolts to the manufacturer’s torque settings (12–14Nm).

Adjusting the SM-BB6800 for Optimal Performance

Once installed, the bottom bracket should be checked for proper alignment and smooth operation:

  • Rotate the crankset to ensure smooth movement without resistance.
  • Check for side play or lateral movement in the crank arms; there should be none.
  • If necessary, adjust the crank preload cap to remove excess play.

Maintenance and Longevity of the SM-BB6800

1. Cleaning the Bottom Bracket

Regular maintenance ensures long life and consistent performance:

  • Remove the crankset every 3,000–5,000 km (or sooner in wet conditions).
  • Wipe down the bottom bracket area with a dry cloth.
  • Use a degreaser if necessary, but avoid high-pressure washing, which can force contaminants into the bearings.

2. Checking for Wear and Replacing the SM-BB6800

  • If you notice gritty or rough rotation, the bearings may need replacement.
  • Unusual creaking noises indicate either dirt contamination or a loose fit.
  • The SM-BB6800 is a sealed unit, so individual bearings cannot be replaced—replace the entire bottom bracket when worn.

Troubleshooting Common Issues

1. Creaking Noises While Pedaling

  • Cause: Dirt, lack of lubrication, or loose bottom bracket cups.
  • Solution: Remove, clean, and reinstall the bottom bracket with fresh grease.

2. Crankset Play or Loose Feel

  • Cause: Incorrect preload adjustment or worn bearings.
  • Solution: Adjust the crank preload cap and check the crank arm bolts.

Comparison: SM-BB6800 vs. Other Bottom Brackets

When considering an upgrade or replacement, it’s useful to compare the SM-BB6800 to other bottom brackets:

  • SM-BB6800 vs. SM-BBR60 [paid link] (Ultegra vs. 105): The SM-BB6800 features higher-quality seals and smoother bearings.
  • SM-BB6800 vs. Dura-Ace BB-R9100: The Dura-Ace bottom bracket is lighter but has similar durability.
  • SM-BB6800 vs. Press-Fit Options: Threaded bottom brackets like the SM-BB6800 are generally less prone to creaking than press-fit alternatives.

Frequently Asked Questions

1. How often should I grease my SM-BB6800?

It’s recommended to regrease the bottom bracket threads and check for wear every 3,000–5,000 km, depending on riding conditions.

2. Can I replace the bearings inside the SM-BB6800?

No, the SM-BB6800 is a sealed unit, so if the bearings are worn out, the entire bottom bracket must be replaced.

3. What torque should I use when installing the SM-BB6800?

The bottom bracket cups should be tightened to 35–50Nm, while crank arm bolts should be 12–14Nm.

4. Why is my bottom bracket creaking?

Creaking can be caused by dirt contamination, loose cups, or worn bearings. Try cleaning and regreasing the threads, then reinstalling with proper torque.

5. Is the SM-BB6800 compatible with all Shimano cranksets?

It is compatible with Hollowtech II cranksets, but not with square taper or press-fit cranksets.

6. How do I know when my bottom bracket needs replacing?

Signs include rough rotation, excessive play, or creaking noises that persist even after maintenance.

Conclusion

Proper installation, adjustment, and maintenance of the Shimano SM-BB6800 bottom bracket will ensure smooth performance and longevity. Regular cleaning and timely replacements will keep your drivetrain in optimal condition. By following the steps outlined in this guide, you can avoid common problems and maximize efficiency on your rides.