I currently have a 30 tooth chainring on my Devinci Kobain. The gearing is a little too tough for my current fitness level. I am considering putting a smaller chainring on it (as per this question).

I would like to know two things:

  1. What is the procedure to change the chainring? I watched the Park tools video on Crank Type Identification but was unable to tell what kind of crank I have.
  2. When looking for a chainring how do I tell if it is compatable with my bike?

Relevant Info

Info on my drive train from Devinci's site:

  • Crankset: FSA COMET MEGA EXO B148 30T
  • Cassette: SHIMANO 10S 11-36T
  • Chain: SHIMANO 10S

Images of my crankset:

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Model Number:

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Right-hand side:

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  • For the record, your crank is a two-piece crank. The spindle is integrated into one of the arms. This crank has direct mount chainrings. That means that the chainrings mount using a splined interface. There are a number of proprietary spline standards. Chances are that, as per the answer, nobody else is making direct mount chainrings based on FSA’s spline standard.
    – Weiwen Ng
    Nov 2, 2019 at 12:04

1 Answer 1

  1. Take the right crank off with a big high-leverage allen wrench or socket (I think it's a 10mm). It's got a self extractor so all you have to do is unscrew it, although occasionally disassembling, cleaning and re-greasing the self extractor is good. Use this special tool to remove the lockring that holds the chainring on. Replace ring, torque lockring. Clean spindle lobes, crank bore, and crank bolt threads, regrease all of them, and put it back together with proper torque.
  2. This is one of the more totally proprietary ones. You need a specific FSA chainring, unless someone is making third party parts for it. I'm not sure whether the extremely similar looking Cannondale standard is actually the exact same spline pattern for the ring/spider. If it is you may be able to get something like this to work, potentially giving you more options, although keeping the chainline right is also a consideration. Same deal with using the other FSA ones such as the Afterburner rings with the same spline pattern - it's possible that each crank model may want a different offset on the ring for correct chainline.

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