Are chain rings universal?

pastryboy
pastryboy Posts: 1,385
edited April 2010 in The workshop
I think my chainset is FSA but the middle ring is worn. I've seen Sora rings quite cheap and want to make sure it would fit ok? (I know some are four and some are five bolt).

Comments

  • wgwarburton
    wgwarburton Posts: 1,863
    pastryboy wrote:
    I think my chainset is FSA but the middle ring is worn. I've seen Sora rings quite cheap and want to make sure it would fit ok? (I know some are four and some are five bolt).

    Nope- you need to know the Bolt Circle Diameter ("BCD") of your chainset. If it's recent then it probably follows one of several standards- most likely Shimano "road" ring 130mm, unless it's a 4-bolt MTB chainset.
    FSA make various triples in road & MTB "standards", so without knowing more about which style you have we can't be sure.

    (Google for BCD and Sheldon Brown for details.)
    Edit- more info & link below.

    Here you go:
    http://www.sheldonbrown.com/gloss_bo-z.html#bcd

    Cheers,
    W.
  • pastryboy
    pastryboy Posts: 1,385
    Thanks - I found the details, it's a 74mm BCD

    http://www.fullspeedahead.com/fly.aspx? ... ut=product

    However, I'm looking at wiggle/chain reaction and hardly anything has a BCD shown so I'm a bit lost on what I need.
  • Pokerface
    Pokerface Posts: 7,960
    pastryboy wrote:
    Thanks - I found the details, it's a 74mm BCD

    http://www.fullspeedahead.com/fly.aspx? ... ut=product

    However, I'm looking at wiggle/chain reaction and hardly anything has a BCD shown so I'm a bit lost on what I need.


    It's a 130BCD for the outer and middle rings. 74 BCD for the small inner ring. That's why you're confused.


    Look for any chainring with a BCD of 130. If it's the middle ring you probably want the 39 teeth option (39t).

    And yes, the Sora ring should fit.
  • pastryboy
    pastryboy Posts: 1,385
    Thanks - I was forgetting the outer and middle ring bolt together.

    I looked on chain reaction and some rings quote pcd, some bcd and some nothing at all. All of which makes it very confusing.
  • Pokerface
    Pokerface Posts: 7,960
    pastryboy wrote:
    Thanks - I was forgetting the outer and middle ring bolt together.

    I looked on chain reaction and some rings quote pcd, some bcd and some nothing at all. All of which makes it very confusing.

    You basically want a road double inner ring. If it mentions 'compact' anywhere then it's the wrong thing (compact rings have a BCD of 110). Also - Campag rings are 135 I think. Avoid those!

    These guys sell a lot of rings: http://www.spacycles.co.uk/

    As do Ribble I think.

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