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Thread: Chainring blues

  1. #1
    Senior Member TimJ's Avatar
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    Currently on my single-speed commuter I've got a crankset with 74 BCD for all the rings. It's a specialized crank, a cheaper model, and the rings are stamped steel, they all attach to the rear of the crank, and the big chainring gets its spacing from being bent outward. I tried finding a decent aluminum chainring with no ramps or pins or anything, 42 tooth, with a 74 bcd, and they don't seem to exist. A straight chainring would work perfectly on this weird cranket. So how I have it is the smallest ring is acting as a spacer for the large ring and that's my single speed crankset. I don't like it though because the ring has filed teeth and stuff for shifting, and the chain wants to jump off- even though the line is really straight. That and it seems flimsy.

    So I got a better specialized crank, this one is the standard sort with the 2 bolting areas, one for the granny the other for the other two, but it's got 86 BCD for the large ring. I can't find a 42 tooth, no ramps chainring with 86 bcd anywhere.

    What I want is, without buying a new crank, to simply have a 42 tooth aluminum chainring with no ramps on my crankset. My options could be simply finding the correct ring with the correct bcd for either crankset, or perhaps for the cheaper crank there may be an adaptor that would allow me to use a higher bcd ring, say 110, with my 74 bcd crank?

    anyone have any idea on that?

    Plus- The regular triple crankset- the 86 bcd- I need to have the chainring where the middle ring would normally set. Does someone make bolts shallow enough to do that or is it necessary to have some sort of spacers? Can anyone tell me how to do this? That is, single ring in middle position on triple crankset, without it being really ugly looking?

    [edited for typos]
    Last edited by TimJ; 01-29-06 at 12:11 PM.

  2. #2
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    An 86 mm BCD is very unusual. Sheldon Brown's web site says only one obsolete Stronlight and a couple of obsolete SR triples used it. Your chances of finding current chainrings for it are remote.

    There should be dozens of NOS or used 110 or 130 BCD cranks available at very low cost if you hunt around. An older LBS may have a drarew full of them.

    There are short chainring bolt sets intended for mounting a single ring on a double crank. Your LBS should have them or they are available at Bike Tools Etc. Look here:

    http://www.biketoolsetc.com/index.cg...item_id=SG-401

  3. #3
    Senior Member TimJ's Avatar
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    Thanks for the link.

    I'm still hoping I'll be able to use one of the specialized cranks. I just like then because they're so purty.

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