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Chainline (yet again!)

Dave BiggsDave Biggs Posts: 136
edited October 2008 in Road general
Just got a sparkly new frame (from a reputable London dealer not a million miles away from KingsX), and am about to build it up.

I did a dry-run build last night to check chainline (its all Miche gear, B/B, crankset, hubs, and sprocket), and noticed that with the right-hand B/B cup flush with the B/B housing, the chainwheel is about 3-4mm too far out.

I know I can adjust it by screwing the cup in a little further, but I would have thought I shouldn't need to given that the running gear's all from the same house, and the frame builders are hardly new to the game.

Is 3-4mm worth worrying about?
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Posts

  • ride_wheneverride_whenever Posts: 13,279
    3-4mm is too much really.

    I've no idea how to remedy it though...
  • meagainmeagain Posts: 2,774
    I'm pretty relaxed when it comes to chain lines, but with all new kit (and much expense!) I reckon 3-4mm on the high side. It is not however uncommon on modern builds (my Tricross Single looks to be about same amount too far out at the front as you describe).

    I know nothing of Miche (I've always avoided because of the carrier-method) but I assume that sealed bearings and thus not easy to move the sprocket outwards? Other than that can you mount the ring on inside of cranks - and if you can will it clear the stays?

    All so much easier with old (and cheaper!) stuff: just custom fit hub and then build rim around it!

    Go and ask 'em I reckon.
    d.j.
    "Cancel my subscription to the resurrection."
  • Assuming the components are intended to be used together something is definitely up. Just because they are the same brand you shouldn't assume that components are compatible, but I've never heard of miche stuff not all having the same chainline.

    Have you checked the BB axle is the right length for your chainset?

    If the components are all matched correctly then you are left with the inescapable conclusion that the frame has been built out of line.

    Having said all that I did know somebody who had a frame built with 135mm spacing when he had a 130mm rear hub. The "kink" in the drive side chain stay to clear the chainrins meant that the drive side "gave" more than the non-drive side. This had the upshot that the wheel pulled out of line to the left when he clamped the QR. He went back to the frame builder complaining that the frame was out of line. He came away with a red face when the builder pointed out his error. Luckilly for him the builder cold set the rear end free of charge.
    "Swearing, it turns out, is big and clever" - Jarvis Cocker
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