How to Install, Adjust, and Maintain the Shimano SM-BB70 Bottom Bracket

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The Shimano SM-BB70 [paid link] is a high-quality bottom bracket designed for Hollowtech II cranksets. Known for its durability and smooth operation, the SM-BB70 [paid link] is a key component in many road and mountain bike drivetrains. However, improper installation, lack of maintenance, or misalignment can lead to premature wear, creaking noises, and power loss.

In this guide, you’ll learn how to correctly install, adjust, and maintain your Shimano SM-BB70 [paid link] bottom bracket to keep your bike performing at its best.

Tools Required

Before beginning, gather the following tools:

  • Shimano Hollowtech II bottom bracket tool [paid link] (e.g., TL-FC32 [paid link] or TL-FC33)
  • Torque wrench [paid link] with a range of 10-40 Nm
  • Grease (lithium or assembly grease)
  • Bottom bracket spacer (if needed, based on frame type)
  • Thread locker (if required for metal-threaded bottom brackets)
  • Clean rag or paper towels
  • Isopropyl alcohol (for cleaning threads and surfaces)

Step-by-Step Installation of Shimano SM-BB70

Proper installation ensures smooth operation and prevents premature wear. Follow these steps carefully.

1. Prepare the Bottom Bracket Shell

Before installing the SM-BB70, ensure your bike frame is ready:

  • Clean the bottom bracket shell thoroughly using isopropyl alcohol and a rag.
  • Check for any dirt, grease, or old thread locker that could affect installation.
  • Inspect the shell for damage, such as cross-threading or burrs.

2. Apply Grease or Thread Locker

Depending on your frame material:

  • For metal-threaded frames (BSA standard): Apply a light layer of grease to the threads.
  • For carbon frames with threaded inserts: Use a mild thread locker to prevent movement without overtightening.

3. Install the Bottom Bracket Cups

The SM-BB70 consists of two separate bearing cups:

  • Thread the right-side cup (marked with “R”) into the drive-side of the frame clockwise.
  • Thread the left-side cup (marked with “L”) into the non-drive side counterclockwise.
  • Tighten both cups using the Shimano bottom bracket tool [paid link]. Torque to 35-50 Nm.

4. Install Spacers (if needed)

If using the SM-BB70 on a 68mm bottom bracket shell, you may need spacers:

  • For road bikes (68mm shell): Use one 2.5mm spacer on the right side only.
  • For MTB (73mm shell): No spacers are needed.

5. Insert the Crankset

Once the bottom bracket is secured:

  • Slide the Hollowtech II crankset spindle through the right-side cup.
  • Ensure a proper fit with no play or resistance.
  • Secure the left crank arm according to Shimano’s recommended torque (12-14 Nm).

Adjusting the Shimano SM-BB70 for Optimal Performance

Proper adjustment ensures longevity and smooth pedaling.

1. Check for Side-to-Side Play

After installing the crankset, check for lateral movement by wiggling the crank arms. If there’s noticeable play:

  • Tighten the left crank arm cap using the Shimano preload tool (TL-FC16 [paid link]).
  • Do not overtighten; apply just enough tension to eliminate play.

2. Test the Smoothness of Rotation

Rotate the crank arms slowly:

  • If the movement feels rough or tight, the bottom bracket may be overtightened.
  • Loosen the crank arm bolts slightly and recheck the preload.

3. Re-Torque the Crank Bolts

Using a torque wrench [paid link], ensure both crank bolts are properly secured:

  • Apply 12-14 Nm for standard Hollowtech II cranks.
  • If using a two-bolt securing system, tighten bolts evenly to prevent misalignment.

Maintenance Guide for Shimano SM-BB70

Regular maintenance prevents creaking and extends the lifespan of the bottom bracket.

1. Cleaning and Re-Greasing

Every 3,000-5,000 km, or if creaking occurs:

  • Remove the crankset and bottom bracket cups.
  • Clean the threads and bearings with isopropyl alcohol.
  • Apply fresh grease to the bearing interfaces before reinstalling.

2. Checking for Wear

Inspect the bearings for the following signs of wear:

  • Grinding or rough rotation: Indicates worn bearings.
  • Side-to-side play: May require a new bottom bracket.

If the bottom bracket is worn out, replace it with a new Shimano SM-BB70.

3. Avoiding Common Issues

  • Do not overtighten the bottom bracket cups, as this can crush the bearings.
  • Use proper grease to prevent corrosion, especially in wet conditions.
  • Check for frame misalignment if persistent creaking occurs.

Troubleshooting Common SM-BB70 Issues

Even with proper installation, some riders may encounter issues:

1. Creaking or Clicking Noises

  • Cause: Dry threads or lack of grease.
  • Solution: Reinstall with fresh grease and check crank bolt tightness.

2. Rough or Stiff Crank Rotation

  • Cause: Over-tightened preload or worn bearings.
  • Solution: Loosen preload slightly or replace the bottom bracket.

3. Excessive Side-to-Side Play

  • Cause: Loose crank bolts or worn bottom bracket cups.
  • Solution: Tighten crank bolts or replace the bottom bracket if needed.

Final Thoughts

The Shimano SM-BB70 is a durable and smooth-running bottom bracket when installed and maintained correctly. Following these steps ensures optimal performance and longevity. Regular maintenance and periodic checks will keep your bike running smoothly for thousands of kilometers.

By following this guide, you’ll keep your Shimano SM-BB70 bottom bracket in peak condition for years to come.