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520 “O” Ring Chain Conversion

Home Forums TR3OC Members Forum 520 “O” Ring Chain Conversion

This topic contains 7 replies, has 5 voices, and was last updated by  Angus McLeod 2 weeks, 4 days ago.

  • Author
  • #8627

    Rowan Geard

    Probably been done to death but I can’t find any posts that lead me in the right direction. Does some one manufacture front and rear 520 sprockets for the triples. I have considered machining the stock units but thought someone out there must be making quality units for our bikes. Please point me in the right direction.

    Thanks in advance.

  • #8629

    Angus McLeod

    Rear sprockets off the 250 single BSAs are 520 and will fit assuming it is a conical hub. I don’t know about other hubs.

    Why do you want to do it? If it is just to fit an o ring chain a DID 530vx will fit.

  • #8636
    Kerrin Gautrey
    Kerrin Gautrey

    Try Les Whiston at Rob North Triples. I think they supply both sprockets to suit a 520 chain but only for a disc rear wheel.

  • #8637

    Martin Rawson

    Angus, doesn’t the wider 520 ‘o’ring chain foul the gearbox sprocket seal holder. As I understand it, this is not a problem if you are running a 20 t sprocket?

  • #8641

    j phillips

    I have a 520 o ring chain on my T150 and ended up machining the front sprocket – the rear is a non standard wheel and a ready made sprocket was easily available.

    I’m putting a five speed box in when I get round to it, so will do the same thing to the 5 sp front sprocket unless I can get one already done that is, as I am going to have to buy a new sprocket and attack it anyway.


  • #8642

    Angus McLeod


    Some o ring chains will foul but the DID one is considerably narrower than any others I’ve seen.  I am running a 20T sprocket but I know someone who fitted one to a standard bike with no problems. Not much clearance though.


  • #8695

    Rowan Geard

    Thanks everyone, Angus, from what I have read I was of the understanding that 530 O ring chains fouled the casing around the drive sprocket.  I figured a 520 O ring would clear as it is not as wide as stock 530 chain.  I am definitely going to fit an O ring chain when I get the bike running – much less maintenance and far cleaner.  So a DID 530VX on a 20T works?

  • #8698

    Angus McLeod

    Yes it does work. If you are going to change the sprocket you might as well machine the oil seal housing just to be sure and at least if you stick with a 530 chain you are not struggling to get 520 sprockets every time you need to replace a sprocket.

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