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  1. #1
    It's the fight in the man Rich's Avatar
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    Chainring Bolt Patterns

    Hi Guys,

    How should I measure my chainrings to find out the bolt pattern?

    I've been given two lenghts to check

    58/94 and 74/110.

    I'm not too sure which one I have.

    Many thanks

    Rich
    Making New Zealand a safer place :)

  2. #2
    Senior Member
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    The Nashbar (USA mail order) catalogue used to have a nifty pattern guide.
    You can make your own with a compass. Draw some concentric circle of suitable diamter (58, 74,94 110 mm). Place the chainrings over, and see which circles hit the centre of the bolt holes.

  3. #3
    It's the fight in the man Rich's Avatar
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    Thanks Michael,

    As always you are the fix it guru!!!

    I honour you!!!!



    Rich
    Making New Zealand a safer place :)

  4. #4
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    You can also try geometry to find the diameter. Divide 360 by the # of bolts, then divide that # by 2. This will give you the half angle of the triangle. The bolt diameter is
    (dist between holes)/{cos(90- 'half angle')**
    (in degrees, of course.)
    Je vais à vélo, donc je suis!

  5. #5
    It's the fight in the man Rich's Avatar
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    Thanks D*Alex,

    Maths was never my fortay..... :confused:

    Rich :blush:
    Making New Zealand a safer place :)

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