The Shimano SM-BB5700 [paid link] bottom bracket, part of the trusted 105 series, is designed for road cyclists who value smooth power transfer and durability. However, improper handling during installation or neglect during routine maintenance can lead to expensive repairs and suboptimal performance. This article explores the most common and costly mistakes riders and mechanics make when dealing with the SM-BB5700 [paid link]—and how to avoid them entirely.
Improper Shell Preparation and Facing
One of the most overlooked yet critical steps before installing the SM-BB5700 [paid link] is ensuring the bottom bracket shell on the frame is properly faced and cleaned. The SM-BB5700 is a threaded bottom bracket (BSA) designed to be installed into 68mm or 70mm shells, depending on your frame specification.
Failing to face the shell surfaces can cause misalignment between the bearings. When bearing cups are not flush with the shell, it results in uneven loading and premature bearing wear. It also introduces creaking under torque loads, often misdiagnosed as crank issues.
Before installing, ensure both sides of the shell are parallel and devoid of paint overspray or debris. This ensures even torque across the bearing cup and optimizes bearing life.
Incorrect Torque During Installation
The SM-BB5700 requires precise torque during installation to ensure it is seated correctly. Shimano recommends a torque of 35–50 Nm for each cup. Over-torquing can lead to thread damage or distortion of the bearing cups. On the other hand, under-torquing can cause the bottom bracket to work loose over time, especially under high pedaling forces.
Using a quality torque wrench [paid link] is not optional—it’s essential. Always use Shimano’s TL-FC32 [paid link] or TL-FC33 bottom bracket tool [paid link] for a secure and accurate fit. Avoid improvising with generic tools that can slip and damage the external notches of the bearing cups.
Mixing Incompatible Grease or Thread Compounds
Thread preparation is another area where mistakes can compromise the longevity of the SM-BB5700. Many riders apply anti-seize, which is not suitable for bottom brackets in alloy frames. It can allow the cups to loosen under load. Conversely, using overly adhesive compounds like Loctite without manufacturer guidance risks making the cups impossible to remove without damage.
Shimano recommends using a waterproof grease for steel and aluminum frames, while carbon frames often require manufacturer-specific compound or bonding agents. Misapplication in this step leads to corrosion, creaking, or a seized bottom bracket.
Neglecting Bearing Seal Orientation
The SM-BB5700 bottom bracket comes with factory-installed seals designed to protect against water ingress. However, incorrect orientation during crank installation can compromise this sealing function. Specifically, pressing the crank spindle through the bearings without aligning the inner seals properly can dislodge or pinch them.
This small oversight often leads to water and dirt intrusion, especially in wet riding conditions, which causes accelerated wear and bearing play. Always ensure the crank spindle slides in smoothly, and verify seal position before final torque.
Skipping Periodic Maintenance
Despite being marketed as “maintenance-free,” the SM-BB5700 benefits from occasional inspection, especially if ridden in wet or dusty conditions. Riders often assume sealed cartridges are immune to contamination, but seal degradation over time is inevitable.
Failure to inspect for play, noise, or tight spots in rotation will result in unnoticed wear. By the time symptoms appear, it’s often too late to salvage the bottom bracket, and replacement is the only option.
Check for side-to-side play and smooth bearing rotation every few months. A simple spin and wobble test while the crank is unloaded can save you from expensive drivetrain wear.
Improper Chainline or Crank Compatibility
The SM-BB5700 is compatible with Shimano Hollowtech II road cranks. Installing cranks with non-standard spindle lengths or mismatched spacers causes chainline deviation, poor shifting, and stress on the bearings. Riders frequently attempt to use non-Shimano or MTB cranks with this unit, assuming Hollowtech compatibility means universal fit—it does not.
Always verify spindle length, crank arm offset, and intended use. Improper crank pairing results in uneven load distribution across the bearings, leading to premature failure.
Overlooking Spacer Requirements
Spacer misconfiguration is another frequent issue. Depending on your frame’s bottom bracket shell width, you may need specific spacers on one or both sides of the bottom bracket. Shimano provides clear instructions for this, but they’re often ignored.
Without correct spacing, the bottom bracket cups won’t preload the bearings properly. This leads to internal play and noise during sprints or climbs. Double-check spacer orientation and count based on your shell width and crankset compatibility.
Using Damaged or Worn Components During Reinstallation
Many riders reuse old cranksets, preload caps, or even worn dust seals during reinstallation after cleaning. However, installing worn parts into a new bottom bracket can introduce contamination and increase the risk of misalignment.
If you’re installing a new SM-BB5700, make sure all interfacing parts—particularly the spindle and preload cap—are clean and undamaged. Even slight wear can compromise the bearing interface, causing unwanted movement and eventual failure.
Forgetting to Retorque After First Rides
Shimano components, including the SM-BB5700, can settle slightly during their first few rides. Failing to retorque the crank preload bolt and crank arm fixing bolts after initial use leads to play that damages both crank and bottom bracket bearings over time.
After the first 50–100 kilometers, re-check and re-torque all fixing bolts to ensure nothing has loosened. This quick step preserves your set-up’s integrity and prolongs the life of the entire system.
Conclusion
Avoiding these common SM-BB5700 bottom bracket mistakes is essential for long-term performance, safety, and cost savings. From installation errors and compatibility misjudgments to overlooked maintenance steps, each oversight has the potential to undermine your entire drivetrain. By following Shimano’s specifications, using the correct tools, and maintaining attention to detail, you can ensure your SM-BB5700 operates smoothly and reliably for thousands of kilometers.