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  1. #1
    mtbr member
    Reputation: Mr. 68 Hundred's Avatar
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    Chainring modification question

    I figured this sub-forum would be better suited to this question than the drivetrain forum.

    I have XTR 980 crankset (using it 1 X 10) and I would like to be able to use the bolt caps that come with it with my Hope IBR. A Race Face narrow wide ring works because the bolt holes are countersunk for the head of the chainring bolt. The Hope ring's holes are not so the stock XTR bolts are too short to be able to thread far enough in to the XTR bolt caps. The Hope ring has enough thickness to counterbore the holes. I have been unsuccessful in finding chainring bolts that would work with the XTR end caps as well as be long enough and have the 'sleeve' that ties the chainring in with the crankarm.

    So, has anyone counterbored a chainring bolt hole before? If so, what sort of bit would I need to use? I spent some time at McMaster Carr but wasn't able to find a proper bit. Possible without a drill press? Any other ideas?

    Thanks y'all
    Steve
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  2. #2
    Framebuilder
    Reputation: Live Wire's Avatar
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    Get chainring nuts that are longer. If they are too long, just cut em down. I did this a bunch back in my ss/fixed building days, was fast and easy.

  3. #3
    No mountains near by :(
    Reputation: bluechair84's Avatar
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    Could look for chainring bolts design to work with a bashplate - they will be longer.

  4. #4
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    Thanks guys.

    The bolt caps act as the nuts so new bolts are whats needed. The Truvativ bashguard bolts are not the right diameter to work with the bolt caps and the e13 turbocharger ones just have long T-nuts, not long bolts. Are there some others I've missed?

    A commercially available bolt would certainly be my preferred option, I just haven't been able to find a bicycle specific one (i.e. one with the 'collar' on it). Anyone used a sleeve bushing (cut to length) on a non-bicycle bolt?
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  5. #5
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    Would either of these do the trick? TA Vega 15mm or Raceface 12.5mm. I'd guess that normal chainring bolts are around 8-10mm long. SJS are a great shop for unusual, obsolete and otherwise hard-to-find bits and bobs.

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