How to Replace the Cable on Your Shimano BB-RS500 for Better Performance

Posted on
in No category

The Shimano BB-RS500 [paid link] is a popular bottom bracket from Shimano’s Hollowtech II range, known for its reliability, smooth operation, and efficient power transfer. Although bottom brackets don’t directly interact with cables like derailleurs or shifters, many riders confuse internal cable routing or frame cable guides with bottom bracket maintenance—especially when cables pass near or through the bottom bracket shell. In integrated systems, especially on modern carbon frames, routing the front or rear derailleur cables through or around the BB area is common.

This article focuses on how to correctly replace and re-route derailleur or brake cables that pass through or near the BB-RS500 [paid link] bottom bracket area. This ensures optimal shifting performance and prevents internal cable wear or interference with the bottom bracket itself.

Tools Required

  1. 5mm hex wrench
  2. Bottom bracket tool [paid link] compatible with Hollowtech II (e.g., Shimano TL-FC32 [paid link])
  3. Cable cutter
  4. Pick tool or cable routing tool
  5. Grease or anti-seize compound
  6. Torque wrench [paid link]
  7. New shift cables and housing
  8. Internal cable guide or magnet-based routing tool (for internal frames)
  9. Clean rags or shop towels

Understanding the BB-RS500 and Cable Routing Integration

The Shimano BB-RS500 [paid link] is a press-fit or threaded bottom bracket (depending on version) designed for Hollowtech II cranks. It doesn’t have internal cable routing channels but often shares space with frame channels when cables run under or through the BB shell.

In carbon or advanced alloy frames, derailleur cables may be internally routed and exit near the BB shell. A poorly routed cable can rub against the BB cups or create friction that impairs shifting.

When replacing cables, it’s critical to:

  • Remove the BB if necessary to access internal cable tunnels
  • Avoid pinching or misaligning cables during reinstallation
  • Protect cables from contamination and frame abrasion

Removing the Shimano BB-RS500 (If Required)

Before routing new cables, inspect whether the BB-RS500 must be removed. In cases of full internal routing or if cable grommets are blocked:

  1. Remove the crankset using a 5mm hex key [paid link] and a crank arm cap tool.
  2. Use a Hollowtech II bottom bracket tool [paid link] to unscrew the BB cups (standard BSA threads).
  3. Clean and inspect the shell for cable guides or obstructions.
  4. If cable entry points are underneath or behind the BB shell, continue to cable removal.

Note: Press-fit BB-RS500 versions may require special press tools to remove the cups without damage. Proceed only if routing access is impossible otherwise.

Routing and Replacing Derailleur Cables

With or without BB removal, follow these detailed steps to route and replace cables:

1. Remove Old Cables and Housing

Begin by loosening the anchor bolts on the front and rear derailleurs. Pull the old cable through the shifter and remove all housing sections.

Check whether cable guides or internal channels run under the bottom bracket. Clean these thoroughly with a rag.

2. Inspect and Clean Cable Paths

Look for any signs of wear, corrosion, or deformation where cables pass near the BB. Pay attention to grommets, stops, and housing end caps.

If cables previously ran through tight passages, apply light grease or a plastic sleeve for future protection.

3. Install New Cables Using a Routing Tool

Use a magnet-based internal routing kit or a feed tool to draw the new cable through the frame’s internal channels. Ensure the path doesn’t pinch against the BB-RS500 shell.

For external cable routing, feed the cable under the bottom bracket shell, using any built-in guides.

Make sure the cable has a clean, smooth arc into and out of the BB area, reducing friction and avoiding sharp bends.

4. Replace Cable Housing and Trim to Fit

Use new cable housing that matches the frame’s previous lengths, or custom trim for smoother routing.

Apply ferrules and rubber boots if applicable, and check that each housing segment ends cleanly at the frame stops.

Use a cable cutter to ensure a clean cut, free of fraying or crushing.

5. Reassemble BB and Crankset

If you removed the BB-RS500:

  • Clean the shell threads or press-fit surfaces.
  • Apply grease (for threaded) or retaining compound (for press-fit) as recommended.
  • Reinstall the bottom bracket using a torque wrench [paid link] set to 35–50 Nm (for threaded BB).
  • Reinstall the crankset, ensuring correct alignment and torque on preload caps and crank bolts.

Ensure cables are not trapped or rubbing during crank rotation.

6. Tension and Fine-Tune the Cables

With the crankset back in place, pull the cables tight and anchor them to the derailleurs.

Shift through all gears, ensuring smooth operation and no cable drag or stuttering around the BB shell.

Adjust barrel adjusters as needed to fine-tune indexing.

Maintenance and Inspection Tips Post-Replacement

To keep the Shimano BB-RS500 and associated cables running smoothly:

  • Regularly inspect the BB area for signs of cable rub or housing wear.
  • Use frame-protective tape or cable liners to reduce friction near the BB shell.
  • Lubricate cables periodically, especially in high-friction zones.
  • Replace cable housing every 6–12 months if shifting starts to degrade.

FAQs

Q1. Does the Shimano BB-RS500 have built-in cable routing?
No. The BB-RS500 itself doesn’t route cables internally but often shares space with internally routed frames where cables pass beneath or through the BB shell.

Q2. Can I route cables without removing the bottom bracket?
Yes, if your frame design allows access to internal guides or external cable stops. However, removal may be required for full internal frames.

Q3. What happens if a cable rubs on the BB shell?
Over time, this can wear through the frame or the BB cup, increase friction, and impair shifting. Proper routing prevents this issue.

Q4. Do I need special tools to replace cables on a BB-RS500-equipped bike?
Only if internal routing goes through the BB shell. A routing tool or magnet guide simplifies the process significantly.

Q5. How often should I replace the derailleur cables around the BB area?
Every 6 to 12 months, depending on usage, weather exposure, and shifting quality.

Q6. What torque should I use when reinstalling the BB-RS500?
Shimano recommends 35–50 Nm for the threaded BB-RS500. Always use a torque wrench [paid link] for accuracy.

Conclusion

Replacing derailleur cables around the Shimano BB-RS500 is a straightforward task if approached methodically. While the BB itself doesn’t interact directly with cables, its position within many modern frames means poor routing can affect overall drivetrain performance. With proper inspection, clean cable paths, and reinstallation procedures, riders can expect crisp, reliable shifting and a longer-lasting drivetrain.