Why Your SM-BB6700 Might Not Be Set Up Correctly and How to Fix It

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The Shimano SM-BB6700 [paid link] bottom bracket is engineered for precision and longevity, designed to pair seamlessly with Hollowtech II road cranksets. However, improper setup—whether during installation, torqueing, or component alignment—can lead to noise, premature wear, and poor drivetrain efficiency. This article provides a comprehensive guide to identifying setup issues with the SM-BB6700 [paid link] and practical steps to fix them, ensuring your ride remains smooth and reliable.

Understanding the SM-BB6700 Bottom Bracket Design

The SM-BB6700 [paid link] is part of Shimano’s Ultegra 6700 series, built around the Hollowtech II interface. It features external bearing cups with integrated seals and is intended for use with English-threaded (BSA) bottom bracket shells.

It is important to note the SM-BB6700’s precise bearing preload and cup alignment requirements. Deviating from these can compromise performance. Recognizing the system’s design helps pinpoint whether a problem stems from installation error or wear-related misalignment.

Signs Your SM-BB6700 Isn’t Set Up Correctly

Several indicators point to incorrect installation or component mismatch:

  • Creaking or ticking noises while pedaling under load
  • Unusual bearing drag or resistance during crank rotation
  • Visible misalignment of crank arms or bottom bracket cups
  • Water ingress or contamination in the bearing cups
  • Premature bearing wear despite low mileage

Identifying these symptoms early can prevent costly damage to both the bottom bracket and crankset.

Common Installation Errors with the SM-BB6700

Incorrect setup usually falls into one of the following categories:

1. Thread Preparation and Frame Interface Issues

Improper cleaning or prep of the bottom bracket shell can result in poor threading engagement and misalignment.

  • Always chase and face the shell using appropriate tools before installation.
  • Inspect for paint overspray or burrs that could affect bearing alignment.

2. Over-Torquing or Under-Torquing the Cups

Shimano specifies 35–50 Nm of torque for bottom bracket cup installation. Exceeding this can damage threads; under-tightening risks cup movement.

  • Use a torque wrench [paid link] with the correct Hollowtech II tool to achieve precise torque.

3. Missing or Misplaced Spacers

Although the SM-BB6700 typically requires no spacers for 68mm shells, misinterpretation of shell width or adding incompatible spacers can alter bearing load.

  • Confirm shell width before installation and consult Shimano’s chart for your specific frame type.

4. Incorrect Crank Arm Preload

Improper crank arm preload is a frequent cause of bearing wear and lateral crank movement.

  • The preload cap on the non-drive side should be snug but not over-tightened. Use Shimano’s TL-FC16 [paid link] tool and follow with pinch bolt torqueing to 12–14 Nm.

Diagnosing Performance Issues Step by Step

To fix an SM-BB6700 setup that feels off, follow a structured diagnostic path:

Shell Preparation Check

  • Remove the cups and clean the bottom bracket shell thoroughly.
  • Inspect for thread damage, corrosion, or contaminants.
  • Re-face the shell if needed to ensure parallel alignment.

Cup Reinstallation and Torque Verification

  • Apply Shimano-compatible anti-seize or grease to the threads.
  • Reinstall cups using a torque wrench [paid link]; verify even engagement.

Crank Installation and Bearing Load

  • Insert the crankset, ensuring smooth passage through both bearings.
  • Adjust the preload cap by hand until snug—no bearing compression.
  • Tighten the non-drive pinch bolts incrementally and to the specified torque.

Testing and Fine-Tuning

After reassembly, assess the setup:

  • Spin the cranks: resistance should be minimal, and no axial movement should be present.
  • Listen for noise under load: ride test at moderate cadence and torque.
  • Check for water ingress or weeping: if present, re-examine seal contact and frame tolerances.

Minor bearing drag is normal in a freshly greased unit but should smooth out after several rides. If issues persist, recheck for frame misalignment or consider bearing replacement if wear is suspected.

Component Compatibility Pitfalls

The SM-BB6700 is compatible only with Hollowtech II cranksets. Using crankarms from different spindle diameters (e.g., 24mm vs. 30mm) or different bottom bracket standards (e.g., BB86 or PF30 [paid link]) introduces stress and alignment problems.

  • Always verify crank-to-bottom bracket compatibility before installation.
  • Avoid mixing components from different series without checking Shimano’s compatibility charts.

Preventive Measures for Long-Term Reliability

To maintain proper function:

  • Re-lubricate threads annually, especially in wet climates.
  • Monitor crank preload torque at regular service intervals.
  • Replace seals or bearing units when rotational resistance increases or contamination is observed.

Conclusion

Improper setup of the Shimano SM-BB6700 bottom bracket can severely impact drivetrain efficiency, rider comfort, and component longevity. By following the correct installation torque, crank preload steps, and frame prep procedures, most issues can be resolved or avoided altogether. Attention to detail during setup and routine inspection ensures your SM-BB6700 operates quietly and smoothly for thousands of miles.

FAQs About SM-BB6700 Setup Issues

1. What torque should I use to install SM-BB6700 cups?
Use 35–50 Nm with a calibrated torque wrench [paid link] and Hollowtech II-compatible bottom bracket tool [paid link].

2. Can I use SM-BB6700 with a BB86 press-fit frame?
No. The SM-BB6700 is designed for BSA-threaded (English) frames only.

3. Why is my crankset rubbing the frame after installation?
This often results from incorrect spacer placement or frame shell width mismeasurement. Reassess the shell specs and spacer chart.

4. Is bearing drag normal on a new SM-BB6700 install?
Some drag is normal due to new grease and seals. It should lessen with use. Excessive drag may indicate over-tight preload or misalignment.

5. How often should I service or re-grease the SM-BB6700?
Inspect every 3,000–5,000 km or sooner in wet or gritty conditions. Re-grease the threads and check for seal wear during inspection.

6. What causes creaking sounds from the SM-BB6700 area?
Common causes include insufficient torque, dry threads, or contamination in the cup/frame interface.