The job
A wrench-driven eight-notch tool for the specifically named cup and e-bike chainring-lockring applications.
Park Tool · Bottom-bracket cup tool
Park Tool BBT-18 Bottom Bracket and Lockring Tool
A wrench-driven eight-notch tool for the specifically named cup and e-bike chainring-lockring applications.
$27.95Nov 7, 26, 12:53 AM · New York
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- Contact Eight notches; nominal 43.4 mm major diameter
- Centre passage 22.5 mm
- Driving flats 36 mm
Contact
Eight notches; nominal 43.4 mm major diameter
Check the centre passage
A matching outer fitting is insufficient if the spindle blocks the tool. This model does not clear a 30 mm spindle.
What this choice changes
Eight-notch engagement with a defined centre clearance
The BBT-18 is useful when the component has the matching eight-notch contact rather than the more familiar 16-notch external-cup fitting. Its nominal major diameter is 43.4 mm, and a separate 36 mm wrench drives the external flats. Count and measure the actual component before choosing it: similar overall diameters can hide completely different engagement patterns.
The 22.5 mm centre passage is just as important as the outer contact. It will not pass over a 30 mm spindle, so matching the outer notches alone does not establish usable clearance. Park Tool names certain externally notched Octalink and ISIS Drive cups, as well as specific Bosch Gen 3/4/5 and Specialized Levo Brose front chainring lockrings.
This range spans different repairs, but it is not a general e-bike tool. Identify the motor generation, lockring or bottom-bracket component and required access. The supplied item is the tool; a 36 mm driving wrench and the bicycle components are separate.
Specifications & supplied details
| Detail | Specification |
|---|---|
| Contact | Eight notches; nominal 43.4 mm major diameter |
| Centre passage | 22.5 mm |
| Driving flats | 36 mm |
| Named e-bike scope | Specific Bosch Gen 3/4/5 and Specialized Levo Brose front chainring lockrings |
| Other named scope | Matching externally notched Octalink and ISIS Drive cups |
| Supplied | One BBT-18; driving wrench separate |
Choose for your actual setup
Check the centre passage
A matching outer fitting is insufficient if the spindle blocks the tool. This model does not clear a 30 mm spindle.
Identify the exact e-bike component
Use the motor generation and lockring fitting, rather than choosing from the word Bosch alone.
Fit checks & limits
- Not suitable over a 30 mm spindle.
- Named motor families do not establish compatibility with every e-bike or lockring.
Questions before you choose
Does it have a square drive?
The established driving interface is a 36 mm external wrench fitting. Plan for a separate suitable wrench.
Why not use the BBT-22 on the same bike?
They address different contacts: BBT-18 has eight notches, while BBT-22 engages a 20-spline cartridge fitting. Match the particular component.
Will this fit any Bosch chainring lockring?
No general claim is established. Park Tool names specific generations and applications; verify the exact lockring and available clearance.
Guides for this choice
Other equipment to consider
Selected listing details, manufacturer information and source images were compared. No hands-on trial or universal fit is claimed. Product identifier: B000R9G7MO.