Running middle rings in outer positions on Middleburn cranks

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  • Running middle rings in outer positions on Middleburn cranks
  • Premier Icon Stoner
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    Anyone doing this?

    I have some RS7s that came with a 110mm BCD 5 Arm spider and rings.
    The middleburn rings are plain Al and 3.5mm wide.

    I can fit the 36T in the outer position and it’s fine. The ring will clear the back of the crank arms and mount flush.

    However, when I try and fit a 5arm middleburn hardcoat (? I think) which is 5.14mm wide the ring is to fat to sit behind the crank arm and still bolt on to the outer position.

    I bought a 4-Arm dual spider so that I could use some 4arm 36T rings I have. Again the same problem, neither of the rings I have iwll mount in the outer position and still go behind the crank arm (Thorn ring = 5.0mm fat and e-thirteen = 3.2mm). The 4arm spider is supposedly for DH etc and gives a 50mm chainline.

    The 5arm spider isnt a new one and seems to give exactly the same chanline as the 4arm Dual spider, so Im not sure it gives the 48mm chainline suggested on the middleburn website for the new spiders.

    Does anyone run a middle ring in an outer position on any 4arm or 5arm spider? and if so which spider and what ring?

    Premier Icon Stoner
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    bump for the Monday morning crowd…

    Premier Icon edd
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    Might be worth calling them on 01420 520223. I’ve found that they don’t always answer but when they do they have good advice. Is this for a Rohloff set-up? I was thinking of doing the same when I had one.

    Premier Icon Stoner
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    edd – yep for a rohloff – ideally want a 54mm chainline, i.e. using the outer ring on a 47.5/50mm middle ring chainline.

    I dropped matthew@middleburn an email still waiting to hear back.

    Ive posted on a similar problem thread on mtbr – unfortunately not much help from there either
    http://forums.mtbr.com/showthread.php?p=5336737#post5336737

    Oddly the 5arm plain middleburn ring is fine, its everything else which doesnt work. I could go round grinding some metal off the rings to creat the space for the arm though. ALternatively I splash out for a 34T Uno ring a new Rohloff sprocket, but thats going to set me back another £60.

    (Im spoompliM over there)

    Premier Icon nickc
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    Can’t you achieve the same thing with a slightly longer BB axle?

    Premier Icon Stoner
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    nickc, back of the class!

    I want to use the outer position for aesthetics not just chainline…durr. 🙂

    Premier Icon nickc
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    You have a clown bike, with a rohloff, and forks with a leg sawn off, and you talk of aesthetics…. 😀 I would have thought where your chainring sits is the least of your worries…

    Premier Icon Stoner
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    to pander to your aesthete sensibilities the frame is currently metamorphosing into a SS with carbon forks so 😛

    Premier Icon nickc
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    the frame is currently metamorphosing into a SS

    Well, at least it’ll look nice(er) as you’re pushing it up those hills… 🙂

    Premier Icon Stoner
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    36:36 is standard SS ratio round these parts…:)

    Premier Icon nickc
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    Grrrrrrrrrr, feel the thighs of steeeel 🙂

    Right, going to work now. As I am very busy and important.

    Premier Icon Stoner
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    had a reply from Matthew @ Middleburn, for those that are interested:

    The XC spiders now run 50mm as well to work with Shimano front mechs.
    The solid 36t ring does fit on the outside of a dual spider.
    We have 36t UNO rings in 1/8 thickness.

    So 2 further solutions there, the solid ring will work with the dual spider

    and although they’re not listed 36T uno’s do exist but would need a SS chain

    So maybe Ill sell on my 36T 4arm rings to fund one of those.

    JoB
    Member

    i had an issue with this once, i simply did some genteel file work to the chainring til it cleared, didn’t have to take much off

    5-arm spider and 34 ring i think it was

    Premier Icon Stoner
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    fortunately my 5-arm and 36T works OK without DIY. Its my collection of 4arms that would need the bodging and since I can get a solid ring for £20 I might just do that – although that’s a more weighty solution than the 86g UNO… 🙂

Viewing 14 posts - 1 through 14 (of 14 total)

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