One of my bikes has an eccentric bottom bracket with a Gates belt drive and a Shimano Alfine 11 IGH.

For a few days now, I've experienced some creaking noise when pushing on the right pedal. Even removing the right pedal, cleaning it, greasing it, and putting it back on didn't solve the issue.

So I figure I should do the same thing with the chainring, but I don't know how to do it: After using a 10mm Allen key followed by an 8mm Allen key, I could successively remove the two screws on the left side (shown as "1" on the picture), but then, I'm left with empty space where a standard bottom bracket axle lives.

Should I use some specific spanner to undo the rings shown at "2"?

enter image description here

Thank you.

  • 1
    It would help to know what brand and model of crank, as well as including a close up pic of area 1 and the screws you removed.
    – Drew Smith
    Jul 29, 2016 at 18:41
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    For an overall description, you will need to remove the crank arm using an extracting tool. You will then be able to extract the drive side crank. You won't need to remove the entire bottom bracket just to remove the crank.
    – Drew Smith
    Jul 29, 2016 at 18:44
  • 1
    Thanks for the help. The crankset says it's a Truvativ Firex. I'll stop at a DIY workshop tomorrow and see if I can remove the left-side crank with an extracting tool, and report back if that solves the issue. Jul 29, 2016 at 19:18
  • Done. You just need to insert an 8mm hex key through the outter ring shown above, and loosen the inner bolt, which will push the crank away from the frame. Jul 30, 2016 at 18:25

2 Answers 2


Those are self extracting crank bolts.

Sram / TruVativ use them. They work like a charm.

The BB cups require a special wrench. The BB should be a Sram / TruVativ GXP.

These require a special wrench that will be referenced as having 16 notches, as there are 16 depressions in your BB.

You can find cheap ones or expensive ones. Up to you.

Remove the BB cups, clean everything really well, grease generously and put a new GXP.

They are well priced, and in my experience they are reliable and efficient. Also you couldn't get any easier to adjust. Good luck!


If you haven't done so already, before taking everything apart you should check the tightness on all the external bits you can, such as both pedals, the eccentric's fastening hardware, your crank bolt, and all chainrings bolts. If you do have to take the BB out, don't forget to also clean and grease all the contact surfaces of the eccentric itself. In fact, with most eccentrics (probably including yours but I can't tell for sure), you can do that without taking the BB out of it if you want.

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