The Shimano SM-BB6700 [paid link] is a Hollowtech II road bottom bracket designed specifically for press-fit applications with threaded BSA bottom bracket shells. It belongs to Shimano’s Ultegra 6700 series, known for high performance and durability. This bottom bracket supports outboard bearing cups and is optimized for 24mm Hollowtech II crank spindles. Installing and maintaining the SM-BB6700 [paid link] requires precision and an understanding of proper torque settings, bearing alignment, and compatibility requirements.
This guide provides a detailed walk-through of everything from initial installation to long-term maintenance of the Shimano SM-BB6700 [paid link], ensuring maximum performance and minimal wear.
Tools Required
- Shimano Hollowtech II bottom bracket tool [paid link] (TL-FC32 [paid link] or TL-FC33)
- 5mm Allen key
- Torque wrench [paid link]
- Anti-seize compound or grease (Shimano recommended)
- Clean rag or degreaser
- Thread locker (optional, for non-cartridge cups)
Preparation Before Installation
Before starting the installation process, ensure the frame’s bottom bracket shell is BSA threaded (68mm or 70mm width) and properly faced and cleaned. Any dirt, paint overspray, or debris must be removed to ensure optimal bearing alignment.
The SM-BB6700 is compatible only with Hollowtech II cranks and a 24mm spindle. Using it with non-Shimano or incompatible cranks can lead to misalignment and premature bearing wear.
Installing the Shimano SM-BB6700
The installation process involves precise application of torque and correct orientation of the cups:
Right Side (Drive Side) Cup Installation
Start with the right (drive-side) bearing cup. This cup contains the inner plastic sleeve and pre-greased cartridge bearings. Apply a thin layer of anti-seize compound or grease to the cup’s threads. Thread it into the bottom bracket shell clockwise (as it is a left-hand thread). Hand-tighten first to prevent cross-threading.
Use the Hollowtech II tool to tighten the cup to a torque specification of 35–50 Nm. Do not over-torque, as it may damage the shell threads or deform the bearing housing.
Left Side (Non-Drive Side) Cup Installation
Apply grease to the threads of the left cup as well. Thread it counterclockwise into the frame (standard right-hand thread). Use the same torque setting to secure it in place. Ensure the plastic sleeve is correctly seated between both cups to prevent water ingress.
Crankset Installation and Bearing Preload
Once both cups are installed:
- Insert the crank spindle through the right side and ensure it slides smoothly through the bottom bracket bearings.
- Use a 5mm Allen key to secure the left crank arm. Tighten the preload cap with the appropriate Hollowtech II preload tool until resistance is felt, then back off slightly.
- Finally, tighten the crank arm pinch bolts to 12–14 Nm, ensuring each bolt is tightened incrementally and evenly.
Improper crank arm bolt torque is a common source of play or bearing wear.
Adjustment After Installation
After installation, spin the crankset to check for resistance or grinding. If resistance is felt, inspect for misalignment or over-torquing. Remove and reinstall if needed. Bearings should rotate smoothly without play. Test ride and recheck torque settings after 20–30 km of riding.
Routine Maintenance
The SM-BB6700 is semi-sealed and requires periodic cleaning:
- Every 2,000–3,000 km, remove the crankset and inspect the bearings.
- Clean the external cups with a rag and degreaser.
- Apply fresh grease to the crank spindle and bearing contact surfaces.
- Check for bearing roughness by spinning them with your finger. If rough or gritty, replace the cups.
This maintenance interval may need shortening in wet or gritty conditions.
Common Installation Issues
Cup Cross-Threading
This typically results from starting the thread with the tool instead of by hand. Always start threads manually to avoid irreversible damage.
Bearing Misalignment
Improper shell facing or installation of cups at different angles causes premature bearing failure. Use a bottom bracket facing tool if the frame is new or previously damaged.
Water Ingress
If the frame sees regular wet rides or cleaning, consider using a light thread locker or marine grease to seal the threads better. Replace the plastic sleeve if it becomes deformed.
Customization and Performance Tuning
While the SM-BB6700 is a high-performance component out of the box, you can improve longevity by:
- Upgrading to hybrid ceramic bearings (compatible models only).
- Adding lightweight grease specifically formulated for high-speed applications.
- Installing crank boots to protect the interface from contaminants.
These changes do not increase peak wattage transfer significantly but do improve durability and feel.
Compatibility Insights
The SM-BB6700 is compatible with:
- Hollowtech II cranksets (Shimano Ultegra 6700, 6600, 105 5700, and Dura-Ace 7900)
- 24mm spindle road cranks from other Shimano lines
It is not compatible with:
- Press-fit BB86/BB90 frames
- 30mm spindle cranksets (e.g., SRAM BB30, Race Face Cinch)
Always verify your frame’s threading and spindle type before installation.
Comparison with Similar Models
Compared to the SM-BB6800 [paid link] (Ultegra 6800), the SM-BB6700:
- Uses steel rather than stainless steel bearing races
- Has slightly higher drag but longer wear in dry conditions
- Lacks the improved water sealing of newer Hollowtech II bottom brackets
Cyclists looking for wet-weather performance may prefer newer models, but for dry, road-based riding, the SM-BB6700 remains highly efficient and durable.
Conclusion
Installing and maintaining the Shimano SM-BB6700 bottom bracket requires attention to detail and the correct tools. When done properly, it provides a stiff, efficient interface for Hollowtech II cranksets and will deliver thousands of kilometers of smooth operation. Regular inspection, cleaning, and adherence to torque specs are key to extending its lifespan.