Niner Biocentric is the asymmetric bottom bracket adapter for a single speed.

Below is the II. I have the I. I could not find a picture of the I. Niner Biocentric II

It is stuck. I have tried penetrating oil for days. On side (drive) moves a little and the other no movement.

Any ideas on how to get it to free up?

Big hammer is not an option.

It used to move OK but it was squeaking a bit so I torqed it to spec and it froze up.

I am thinking about taking it apart but right now I cannot get my Raceface Evolve crank off.

  • 2
    Fuzzy but I think they can respond to loosening the bolt such that it's still engaged with the thread, putting a punch down in the bolt head recess, and bonking hard on the punch. Also could be a good candidate for Finish Line Chill Zone. That's been my go-to for a couple years now and I find there's not a lot of bike things where using a sufficient amount of it all at once and soaking won't free up. Dec 23, 2017 at 19:56
  • I've never used one of these - is the asymmetric adapter stuck in the frame, or is there a cartridge BB stuck in the adapter?
    – Criggie
    Dec 23, 2017 at 20:19
  • @Criggie See the picture. Yes the adapter is stuck in the frame.
    – paparazzo
    Dec 23, 2017 at 20:23
  • @NathanKnutson I almost went that route but was able to pry one side off then punch the other out.
    – paparazzo
    Dec 24, 2017 at 14:21

1 Answer 1


I ended up taking it apart, clean, polish with 600 sandpaper, and grease. Got it to move / rotate.

It was very dirty as I used that bike to explore the city during a flood.

If you have this setup I recommend you tear it down and clean every couple years and after submerging in muddy water.

Comment from Nathan is valid if it is totally frozen. But I would recommend a separate longer bolt.

Got the slack out of the chain:
Got the slack out of the chain

  • 1
    Good work - I'd strongly recommend an assembly grease like "copperslip/coppaslip" on every contact surface when you reassemble. Its less likely to was out than normal grease over time. However if yours was assembled dry originally then any grease is better than none.
    – Criggie
    Dec 25, 2017 at 1:17

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