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

What Tools do I need?

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

Park Tool BBT-18 Bottom Bracket Tool securing chainring lockring on Bosch® e-bike system

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

Park Tool LRT-3 Lockring Tool shown near a FSA 4-notch lockring

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

Park Tool LRT-1 Lockring Tool — Bosch® Gen 2 next to compatible lockring

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

Park Tool LRT-4 Lockring Tool Shimano® Direct Mount driven by a TWB-6.2 and torque wrench

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.