• I couldn’t find any 40t+ chainrings. Bought a Miche Primato chainset and a 127mm un55 BB. If the chainset has a 42mm chainline on a 107mm BB, I should get a 52mm on a 127mm BB, no? This should give me a starting point and I’ll swap out the BB with a lighter one when it is all set up.

  • If the chainset has a 42mm chainline on a 107mm BB, I should get a 52mm on a 127mm BB, no?

    Maybe, I can't remember whether the 127mm UN55 is symmetric. If it isn't, you've probably gone too far 🙂

  • Maybe, I can't remember whether the 127mm UN55 is symmetric. If it isn't, you've probably gone too far 🙂

    I’ve been looking at the UN55 BB data online and although I can’t find anything for a 127, I have for a 122mm.

    Stated length 122mm
    Actual length 123.2mm
    Right hand stick out 28.6mm
    Left hand stick out 26.6mm

    This should give me a 51.2mm chainline and with a 1mm spacer on the drive side a 52.2mm. 0.3mm out but I think I can deal with that.

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