Chainring Lockring Tool Selection
Chainring lockrings have become a more popular feature on new bicycles, particularly on e-bikes. This article will review the selection of Park Tool options for various chainring lockring systems.
Preliminary Info
- Digital caliper, such as Park Tool DC-1
To determine the correct tool, begin by inspecting the chainring lockring. In most cases it will be necessary to remove the crank in order to measure and determine the tool choices.
Tool fittings can be notches or indentations on the outer perimeter or splines on the inside perimeter. Count the number of tool fittings on the cup.
Next, use a caliper to measure the diameter or width of the tool fittings. For external notches, first measure the outer diameter of the lockring. This is the major diameter of the tool fitting. For tool fittings with internal splines, measure to the outer bounds of where the tool would fit.
It can be difficult to get exact measurements. For most models, getting within a millimeter will be good enough to get the correct tool.
Tool Finder Table
Use the table below to find the best match, and click the name of the tool to see an example of the tool fitting as well as a list of popular brands that feature this fitting. There may be some proprietary styles not listed here.
| Tool Fitting | Dimension | Tool |
|---|---|---|
| 8 external notches | 40–45 mm OD | BBT-18 |
| 4 or 8 external notches | 47–48 mm OD | LRT-3 |
| 8 external notches | 50 mm OD | LRT-1 |
| 16 external notches | 39–40 mm OD | BBT-49.3, BBT-29 |
| 16 external notches | 41 mm OD | LRT-4 |
| 16 external notches | 44–45 mm OD | BBT-69.4, BBT-19.2, BBT-9 |
| 16 external notches | 54 mm OD | LRT-2 |
| 20 internal splines | 31.5 mm ID | BBT-22, BBT-32 |
Tool Fittings
8 External Notches, 40–45 mm OD
Examples include:
- Bosch® Gen 3 and Gen 4 e-bike systems
- Specialized® Levo Brose e-bike systems
Use Park Tool BBT-18.
4 or 8 External Notches, 47–48 mm OD
Examples include many direct-mount chainring models:
- Cannondale® Hollowgram
- FSA® BB386EVO
- FSA® BB392EVO
- FSA® MegaExo
- Specialized® S-Works
Use Park Tool LRT-3.
8 External Notches, 50 mm OD
Examples include:
- Bosch® Generation 2 Active Line (chainrings less than 20 teeth)
- Bosch® Generation 2 Performance Line
- Bosch® Generation 2 Performance Line CX
Use Park Tool LRT-1.
16 External Notches, 39–40 mm OD
Examples include Shimano® STEPS square spindle e-bike systems such as:
- Shimano® E6000
- Shimano® E6002
- Shimano® E6050
Use Park Tool BBT-49.3 or BBT-29.
16 External Notches, 41 mm OD
Examples include many Shimano® direct-mount chainrings, such as:
- Shimano® XTR® 9120
- Shimano® XT® 8120
- Shimano® MT900
- Other Shimano® direct mount systems
Use Park Tool LRT-4.
