Dismantled my bike to try and take a look at the crank bearing, as I fear it may be getting dry. Unfortunately at the stage pictured I could go no further.

The outer and inner rings appear to be separate, and locked against each other (presumably to set the end-float of the axle?). No idea what kind of fixing this is, so also no idea what sort of tool is required.

Does anyone recognise it?


bottom bracket

  • Can you show some more pictures from other angles? Mar 5, 2015 at 0:18
  • 1
    You sure that arrangement isn't simply to secure that bracket? Mar 5, 2015 at 1:50
  • If you're just trying to clean and lube the bearings, you shouldn't have to remove the right-side cup at all. What does the left side look like? I bet if you get that unscrewed, the spindle will come out, and you'll have access to the bearings. Mar 7, 2015 at 1:26

2 Answers 2


That's the chain guard bracket and it would likely come off with a bottom bracket lockring tool. The fixed cup of the bottom bracket should be behind it.



This tool should do to remove the lockring at which point the chaincase mount should be able to be removed.

The inner indents don't look to match any splined BB tool I've ever come across though.

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