How to Replace the Cable on Your SM-BB9000 for Better Performance

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The Shimano SM-BB9000 [paid link] is a premium bottom bracket designed specifically for the Dura-Ace series. As a component directly involved in the efficient transfer of pedaling force, it is essential to ensure every related system functions optimally. While the SM-BB9000 [paid link] itself doesn’t directly house a cable, many users refer to cable replacement in the context of the drivetrain system it’s part of—particularly for front and rear derailleurs that rely on properly routed and tensioned shift cables. If these cables aren’t operating smoothly through the bottom bracket shell or under-frame cable guides, drivetrain performance can be compromised.

This guide walks you through replacing the derailleur cable system that interacts with the SM-BB9000 [paid link] installation area to ensure peak performance of the entire drivetrain setup.

Understanding the SM-BB9000 and Its Role in Cable Routing

The SM-BB9000 uses Shimano’s Hollowtech II design, which integrates the bottom bracket with external bearings for better stiffness and lighter weight. It’s typically paired with Dura-Ace 9000 series cranksets and is housed within a standard threaded 68 mm or 70 mm bottom bracket shell.

In many road bike designs, the shift cables (especially for the front derailleur) pass underneath or through the frame near the bottom bracket shell. Over time, cables can degrade, fray, or become contaminated at these junctions, affecting shifting precision. Thus, periodic replacement of cables that route in the proximity of the SM-BB9000 is critical for maintaining drivetrain integrity.

Tools Required

  • 5 mm Allen key
  • Torque wrench [paid link]
  • Shimano cable cutter or equivalent
  • Inner and outer gear cables (Shimano or high-quality alternative)
  • Cable end caps and ferrules
  • Frame-specific internal routing tools (if applicable)
  • Grease and/or frame protector paste
  • Optional: Replacement under-bottom-bracket cable guide (if worn)

Step-by-Step: Cable Replacement Around SM-BB9000

Accessing the Cable Routing Area

Start by removing the crankset to expose the cable guide underneath the bottom bracket shell. With the SM-BB9000 system, the non-drive side crank arm is secured with a pinch bolt system, and removal allows for complete access to the underside of the bottom bracket where cables typically run.

  • Loosen and remove the two 5 mm Allen bolts on the non-drive crank arm.
  • Remove the safety cap and pull the crank arm off the spindle.
  • Gently slide the crankset spindle out from the drive side.

With the crankset removed, inspect the cable guide located beneath the SM-BB9000 shell. If it shows excessive wear or grooves, consider replacing it. Clean the area of dirt and lubricate the guide channel lightly with silicone-based grease.

Removing the Old Cables

Shift the derailleurs to their smallest gears to release maximum cable slack. Cut the cable ends, then use the derailleur barrel adjusters to relieve additional tension.

  • Unfasten the cable fixing bolts on both front and rear derailleurs.
  • Carefully pull the cables out from the frame, starting from the derailleur side and working backward toward the shifters.
  • If your frame has internal routing, use a cable guide tool or string to trace the cable path during removal. This ensures easier reinstallation.

Installing the New Cables

Feed the new cable into the shifter lever first. Ensure smooth, resistance-free entry. For bikes with under-BB cable routing, direct the cable through the cable guide beneath the SM-BB9000.

  • Insert the cable into the housing or liner and feed it along the path previously traced.
  • Re-lubricate the cable guide if needed before the cable enters and exits this section.
  • Confirm that the cable sits securely and doesn’t rub unnecessarily against the bottom bracket or frame.

Attach the cables to the derailleurs and pull taut. Use the correct torque when tightening the cable anchor bolts—typically around 5–7 Nm for Shimano derailleurs.

Cable Tension and Indexing

Once the cables are attached, shift through each gear to ensure crisp, accurate movement.

  • Use barrel adjusters to fine-tune indexing.
  • For front derailleurs, set the high and low limit screws before dialing in the tension.
  • Make sure there’s no excessive friction at the cable guide beneath the SM-BB9000. A sticky guide here can severely affect front shifting performance.

Finishing Touches

  • Crimp cable ends to prevent fraying.
  • Reinstall the crankset into the SM-BB9000 bottom bracket. Apply light grease to the spindle and ensure correct torque when tightening the crank bolts (12–14 Nm typically).
  • Test ride and listen for clicking or dragging, especially near the bottom bracket area. These may indicate poor cable alignment or tension near the SM-BB9000 guide.

Optimizing Cable Performance with SM-BB9000

To enhance shifting performance and prolong the lifespan of your drivetrain:

  • Use low-friction inner cables (e.g., Shimano Optislick or polymer-coated options).
  • Routinely inspect the under-bottom-bracket guide for dirt and replace it annually if heavily used.
  • Consider cable liners inside the guide for extra protection against contamination.
  • Avoid overtightening the crankset, as this can deform the cable path slightly if components are misaligned.

Common Issues and Troubleshooting Tips

Issue: Stiff front shifting after cable replacement
Cause: Cable housing compressed under the BB shell or improper guide seating
Solution: Reroute the cable ensuring proper housing length and smooth flow through the guide

Issue: Clicking sound during pedaling
Cause: Misrouted cable under BB shell rubbing against crank spindle
Solution: Inspect routing and verify cable doesn’t interfere with crank movement

Issue: Inconsistent shifting across rear cogs
Cause: Cable tension imbalance, often stemming from the under-BB cable section
Solution: Readjust tension and inspect for cable kinks or housing deformation

Final Thoughts

While the SM-BB9000 bottom bracket itself doesn’t require direct cable servicing, its role in supporting cable routing cannot be underestimated. Proper replacement of derailleur cables around the BB area, especially through or under the cable guide beneath the shell, is critical for drivetrain efficiency. With correct technique, quality components, and attention to detail, you can restore and even enhance your bike’s performance to match the standards of Shimano’s Dura-Ace system.