Actual XX crank q-factor?- Mtbr.com
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  1. #1
    breathing helium
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    Actual XX crank q-factor?

    I have a question about the xx crank q-factor. I am going to have a custom frame built so that it will be able to run the lowest q version, 156mm. Has anyone measured the q of their xx cranks? Is it actually 156?

    The reason I ask is that SRAM quotes a q of 145for their force road cranks, yet they measure more like 150. I have a really sensitive knee and need to get the q as close to road width as I can. I would hate to buy the cranks (as I did with force) only to find out that they will not work for me.

    Thanks!

  2. #2
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    The q-factor on the SRAM chainset takes its measurement from the internal faces of the crank I believe and its a fairly reliable measurement.

    I've just had a custom Baum Ti frame built and I'm running the 156 cranks with a Chris King bottom bracket. Set-up works really very well. Probably worth getting a King BB from outset tho'...

  3. #3
    Kam
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    Quote Originally Posted by bobsouth
    The q-factor on the SRAM chainset takes its measurement from the internal faces of the crank I believe and its a fairly reliable measurement.

    I've just had a custom Baum Ti frame built and I'm running the 156 cranks with a Chris King bottom bracket. Set-up works really very well. Probably worth getting a King BB from outset tho'...

    baum ti....nice! post some pics!

    as for the xx 156 q measure.....it is taken from the inside to inside of the crankarms? you sure?

    i am pretty sure the crankarms areatleast 5mm thick, so you can easily add another 10mm for the pair...so total would be 166 or greater and that would be no less than the xtr 960 or 760 and most of the other external bb cranksets out there.

    can someone please take a ruler and measure this sh!t!
    "forget kings...forget hadleys......they all have crap engagement. just run your bike fixed gear." - FoShizzle

  4. #4
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    It is my understanding that q is measured from the outside edge of the crank arms. If the pedal threads are recessed, I guess you should measure from there. If someone could measure their cranks, it would be greatly appreciated I usually put a small piece of tape on the seat tube as a reference point and measure each side from there.

  5. #5
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    See this: http://www.sram.com/_media/techdocs/...ifications.pdf

    I assume that Sram measures Q in the normal way; that would mean the cranks are 12.3mm thick, which is about what I'd expect.

  6. #6
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    Thanks, I've seen that PDF. I was hopeful that someone had an actual measurement from their bike.

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