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  1. #1
    King of the Hipsters
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    2005 Bianchi Pista Riders Only

    I recently ordered and received a Sugino/SR 130 BCD chainring and an EAI 3/32 sprocket from Harris Cyclery.
    I installed the sprocket so that the flange faced towards the center of the hub, and I installed the chainring on the outer position of the Sugino RD crank that came with my 2005 Bianchi Pista.
    As a result I have the most perfect chainline imagineable.
    I look at it and look at it to see if I could improve it in any way, and I can't.
    I declare this crank, chainring and sprocket combination perfect.
    Absolutely perfect.

    I chose a 47t chainring and a 17t sprocket, but I noticed that Harris Cyclery has a 45t, 50t and a 52t chainring with the same nomenclature as my perfect 47t chainring.
    In the outer position, I know the 50t ring would clear the chainstay, and I think with almost complete certainty the 52t ring would clear the chainstay.
    EAI makes 13t-22t 3/32 sprockets and Harris has 'em.
    52X18 with a 23mm tire would give 75.9 gear inches.
    My setup of 47X17 with a 23mm tire gives me 72.9 gear inches.

    The point: a perfect chain line with off the shelf parts and requiring almost no special skills and a minimum of tools.

    http://sheldonbrown.com/harris/chainrings/130.html#47
    http://sheldonbrown.com/harris/fixed-sprockets.html

    Like I said, 2005 Bianchi Pista riders, only.

  2. #2
    Banned zelah's Avatar
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    i ride a surly, but i opened the thread anyway...i'm sorry

  3. #3
    Mo' Senior SSSasky's Avatar
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    1984 Norco Monterey SL (Ishwata 3X butted), matte black, 42-15 fixed
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    I got absolutely perfect chainline with an IRO drivetrain upgrade ... I already had the hubs, but any hub with a 42mm chainline will work ... $125 for cranks, chainring, BB, chain and new Soma cog. Works great.

    I've never even seen a Bianchi Pista in person.

  4. #4
    Senior Member
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    So Ken, are you saying that you flipped the cog around so that the chainline moves outboard? I also have a 2005 Pista, and I recently configured the chainline in a similar manner. I moved the stock 48t chainring to the outer position, and replaced the stock cog with a 15t Dura-Ace. This gives a 47mm chainline in the back, and a 49mm chainline in the front. I rode it on the velodrome like this, and it performed all right, though it was a little noisier than usual. However, 2mm seems like a lot of discrepancy, and I imagine that it will result in increased wearing of the drivetrain components, so I'm probably going to change it back to its original configuration with the chainring on the inside position, and with the flat side of the cog pressed up against the hub.

    All of this leads me to believe that the EAI cog must be a couple of millimeters thicker than the Dura-Ace. Hmm, interesting.

  5. #5
    King of the Hipsters
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    Lunacycle wrote:

    "All of this leads me to believe that the EAI cog must be a couple of millimeters thicker than the Dura-Ace."

    Sheldon Brown has an online table somewhere that gives the thickness of the various manufacturer's cogs.
    I have three cogs by three different manufacturers (Soma, Dura Ace and EAI), and they have significant differences, not only in oveall width, but as to where the center line of the cog teeth falls in the overall width.
    If I put all three of them on a flat table, the teeth don't line up in the same plane with each other, and dramatically so.

    The same applies to the two chainrings.
    They not only have a different overall thickness, but the stock Sugino chainring has slightly biased teeth, so that flipping it over could move the teeth left or right, but I find the whole design so assymetric and confusing I can't tell.
    The Sugino/SR chainring sold by Harris (43t, 45t, 47t, 50t and 52t) has a completely different and symmetrical design, very simple in nature; it seems intended as a track ring and of much better quality than the stock ring.

    This combination and placement of chainring and cog represents a happy accident.
    I didn't do this intentionally, and only noticed it after playing with the parts for awhile.
    With the EAI cog and the Sugino/SR chainring, it only works with the cog flange against the hub and the chainring in the outboard position.
    I suspect other cog orientations, chainring sizes and chainring postions on the star will acheive the same result.
    This one, however, works and I wanted to report it.

    Also, putting the chainring on the outboard position of the star makes enough room for even a 52t chainring to clear the chainstay.
    I haven't put a 52t ring on to verifiy this; it just looks like will fit, easily.

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