The Gateway to Your BB
To service your bottom bracket (BB), the first step is removing the crank. Sounds technical? With the right tools and a bit of patience, it’s actually straightforward.
Crank Types
| Type | Removal Tool | Common Brands |
|---|---|---|
| Square Taper | Crank puller | Older bikes, entry-level bikes |
| Octalink | Crank puller | Older Shimano |
| External (Hollowtech II) | 5mm hex + crank cap tool | Modern Shimano |
| Self-extracting (SRAM DUB) | 8mm hex | Modern SRAM |
| Ultra-Torque (Campagnolo UT) | Dedicated tool | Campagnolo |
Shimano Hollowtech II Removal and Installation (Most Common)
Removal
- Use a crank cap tool (TL-FC16) to unscrew the left-side cap counterclockwise
- Use a 5mm hex wrench to loosen the two pinch bolts on the left crank arm
- Gently pull off the left crank arm
- Slide the entire spindle + right crank arm + chainrings out from the right side
Installation
- Insert the spindle through the BB from the right side
- Fit the left crank arm, making sure the alignment marks line up
- Tighten the two pinch bolts alternately (12-14 Nm)
- Attach the cap (finger-tight is enough, no need to force it)
SRAM DUB Removal and Installation
Removal
- Use an 8mm hex wrench to unscrew the left-side self-extracting bolt counterclockwise
- Once the self-extracting bolt comes out, the left crank arm can be pulled off
- Slide the spindle out from the right side
Installation
- Insert the spindle from the right side
- Fit the left crank arm
- Thread in the self-extracting bolt (54 Nm — this torque is quite high and requires real force)
Things to Watch Out For
| Key Point | Explanation |
|---|---|
| Remember orientation | Crank arms are left/right specific — don’t install them backwards |
| Clean the spindle | Wipe it clean after removal before reinstalling |
| Don’t force it | If it won’t pull off, gently rock it side to side |
| Torque values | Tighten strictly to spec |
| Prevent seizing | Apply a thin layer of grease (metal) or anti-seize/carbon paste (carbon) to the spindle |
Once you’ve mastered crank removal and installation, you’ll be able to handle BB cleaning, chainring replacement, and deep maintenance of the drivetrain yourself. Congratulations on leveling up!
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