WORKSHOP WEDNESDAY - HOW TO FIT A SHIMANO BOTTOM BRACKET

Workshop Wednesday: How to fit a Shimano bottom bracket to your bamboo bicycle frame.

The bottom bracket (BB) is one of the most important components on your bamboo bicycle — it houses the bearings that allow the crankset to rotate. Getting this right is essential for smooth pedalling and long-term reliability. This guide covers fitting a Shimano threaded bottom bracket to a BBC frame.

"The whole goal of Bamboo Bicycle Club is to make bike-building accessible to everyone."

Bottom Bracket Standards

BBC frames are built around a threaded bottom bracket shell (either BSA/English thread or Italian thread). The shell is pre-installed during the frame build and accepts standard threaded Shimano bottom brackets including the Hollowtech II external bearing units (SM-BB52, SM-BB70, SM-BB72) used with most Shimano groupsets.

Tools Required

• Shimano TL-BB13 bottom bracket tool (or compatible splined tool)
• Torque wrench
• Grease (waterproof bearing grease)
• Chain whip (for holding the BB shell during tightening)

Step-by-Step Fitting

1. Chase the threads: Before installation, run a bottom bracket tap through the shell to ensure clean threads. Even if the shell is new, this removes any debris from the build process.
2. Grease the threads: Apply a thin layer of waterproof grease to the BB cup threads. This prevents seizing and makes future removal easier.
3. Note the thread direction: BSA (English) threading has the drive-side cup with left-hand (reverse) thread and the non-drive side with right-hand thread. Don't cross-thread.
4. Hand-tighten first: Thread both cups by hand to check alignment before applying any tool torque.
5. Torque to spec: Use the Shimano splined tool and torque to 35–50 Nm. The bamboo shell insert is robust but don't over-tighten.
6. Install crankset: Follow Shimano's Hollowtech II installation procedure — insert the left crank axle, torque the pinch bolts to 12–14 Nm.
7. Check for play: With cranks installed, check for lateral play by pushing/pulling the crank arms sideways. Adjust the pre-load cap if needed.

"Founded in London in 2012 by James Marr, bamboo is said to have ideal properties for bike construction with its 'excellent vibration dampening effects', resistance to stress and durability."

Watch the full Workshop Wednesday video on the BBC YouTube channel for a step-by-step visual guide to Shimano bottom bracket installation.