The Most Common SM-BB93 Problems and How to Solve Them

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The Shimano SM-BB93 [paid link] bottom bracket is a high-performance component designed specifically for road bikes using Hollowtech II cranksets. Renowned for its low weight and reduced friction, this press-fit bottom bracket serves as a crucial link in the power transfer system. However, even precision-engineered parts like the SM-BB93 [paid link] can develop issues over time or due to incorrect installation and usage. Understanding these common problems and how to fix them ensures reliable operation and prolonged component life.

Creaking and Unwanted Noises During Pedaling

One of the most frequent complaints among users of the SM-BB93 [paid link] is creaking sounds during pedaling. While often attributed to the bottom bracket itself, the source may originate from poor installation practices or related components.

Causes:

  • Inadequate press-fit installation leading to poor contact between the bottom bracket shell and the frame.
  • Dry or contaminated interfaces between the bearing cups and frame.
  • Crank arm or chainring bolts not torqued to specification.

Solutions:

  • Reinstall the bottom bracket using a quality press-fit tool. Clean all contact surfaces and use Shimano-recommended grease.
  • Check for signs of wear or scoring on the shell and cups, which may indicate ovalization or contamination.
  • Torque crankset bolts evenly to Shimano’s recommended values (typically 12–14 Nm for Hollowtech II arms).

Bearing Roughness and Resistance

Smooth bearing operation is critical for the SM-BB93’s performance. If pedaling feels gritty or uneven, the bearings may be contaminated or worn.

Causes:

  • Water ingress due to compromised seals or aggressive cleaning methods.
  • Dust or road grime penetrating the bearing seals.
  • Long-term use without appropriate maintenance.

Solutions:

  • Remove the crankset and inspect both sides of the bottom bracket for signs of corrosion or dirt.
  • Clean thoroughly using a degreaser and re-lubricate with waterproof grease.
  • If roughness persists, replace the SM-BB93 bearing cups entirely, as they are not serviceable.

Bottom Bracket Play or Lateral Movement

Any side-to-side movement in the crankset indicates that the bottom bracket is not providing adequate support.

Causes:

  • Improper preload adjustment on the Hollowtech II crankset.
  • Worn-out or deformed frame shell causing misalignment.
  • Missing or improperly installed preload cap or wave washer.

Solutions:

  • Adjust the crank arm preload cap with Shimano’s TL-FC16 [paid link] or TL-FC18 tool until there is no play but rotation remains smooth.
  • Inspect the frame shell width and roundness using calipers to ensure it meets Shimano’s specifications.
  • Confirm that all hardware is present and correctly installed, including spacers if required for your specific frame standard.

Press-Fit Shell Cupping or Ovalization

Because the SM-BB93 uses a press-fit interface, it is particularly susceptible to frame manufacturing tolerances. If the frame shell is not perfectly round, issues such as bearing misalignment and cup migration can occur.

Causes:

  • Frame shell diameter exceeding Shimano’s tolerances (typically 86.5mm width, 41mm ID).
  • Repeated installations wearing down the carbon or aluminum interface.

Solutions:

  • Measure the shell ID and roundness before installation. Use a bore gauge if possible.
  • For out-of-spec shells, consider using a bottom bracket with a threaded or eccentric design for better retention.
  • Apply retaining compound (such as Loctite 641) when installing the SM-BB93 into slightly loose shells to reduce the chance of movement.

Rapid Wear or Short Service Life

While designed for performance, the SM-BB93’s lightweight construction makes it more prone to wear under certain conditions.

Causes:

  • Heavy rider load, poor weather riding, or off-road use despite being a road-specific component.
  • Frequent power washing or use of solvents on the frame area.

Solutions:

  • Replace the bottom bracket every 5,000–8,000 kilometers for optimal performance, depending on riding conditions.
  • Avoid high-pressure water directly on the bottom bracket area during cleaning.
  • Use a frame protector or mudguard if riding in adverse weather to reduce contamination exposure.

Difficult Crank Removal or Installation

Improper handling during crankset installation or removal can damage the SM-BB93 or lead to misalignment issues.

Causes:

  • Inserting the crank arms without aligning the splines properly.
  • Overtightening preload or fixing bolts.

Solutions:

  • Carefully align crank splines with the bottom bracket spindle, ensuring full engagement before applying torque.
  • Follow Shimano’s torque specification guidelines and use only the correct Hollowtech II tools.

Conclusion

The Shimano SM-BB93 is a top-tier bottom bracket when installed and maintained correctly. Many issues arise not from the component itself, but from improper installation or frame compatibility problems. By identifying the source of common complaints—such as creaking, rough bearings, or crank play—and applying the correct fix, cyclists can restore optimal function and prevent premature wear. Regular inspections and attention to detail during setup will ensure that your SM-BB93 remains a reliable part of your drivetrain.