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Thread: Q factor??

  1. #1
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    Q factor??

    Can someone explain what the heck the difference between 156 &166 q factor is regarding cranks? Just got a stumpy evo frame and the whole press in bb is new to me. While were at what's the dif between BB30 & FB30, guessing the od of the bearing as cranks seem to be compatable between the two?

  2. #2
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    Q factor is the distance between the centers of the holes for the pedals. You would need a Q168 for the stumpy.

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    Got it, and is kinda what I figured, Thanks mang

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    Can't help much regarding the qfactor, since I don't really understand it nor have I experimented with different options. I just always hear that the lower the q factor the better? Probably only applies to XC racing..but what do I know.

    Pf30 and bb30 are similar in which you can run bb30 cranks on pf30 bb's...but the actual design is different. If you search for a bb30 image, you'll see. The bb30 uses bearing which are held in place by c clips or snap rings (please correct me if I used the wrong term). A pf30 bb is actually a shell with sealed bearings inside which better keep out the elements. The pf30 seems to be a better option since the bearings are less exposed. On bb30 bb's...you often will ruin the bb if water somehow enters the frame. I've heard a lot of bb30 failures, but very little pf30.

    Also keep in mind that shimano hasn't given in to the bb30/pf30 standards, and you will need adapters. The bb30 cranks have a larger spindle, which allows them to use lighter weight material and still plenty stiff. On the smaller diameter spindles, they need to use a stronger (heavier) material to keep stiffness/durability. Is there much difference? I've never noticed any. Use whatever works best for your setup. I was happy with my threaded bb's for ease of maintenance...but my new niner frame uses pf30 so I had to learn about these new industry standards.

  5. #5
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    Now I'm wandering since cranks like sram xx1 come with such specific q-factor (156,166,168) , can you use spacers on them like other outboard 24mil cranks?

  6. #6
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    Quote Originally Posted by big JC View Post
    Now I'm wandering since cranks like sram xx1 come with such specific q-factor (156,166,168) , can you use spacers on them like other outboard 24mil cranks?
    You could, but that would only change the chain line. The Q factor would remain the same though.

  7. #7
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    Does any body know the Q factor for SRAM Truvativ Stylo cranks?
    How about SRAM S2200 cranks? (the carbon cranks that are equivalent to XO cranks)

    Thanks in advance!

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    The bigger Q-factor is used to help the crank arms clear the rear suspension on bikes (afaik), like was said above it is the width of the cranks from pedal to pedal. This measurement is also independent of the spindle length, meaning the wider q-factor doesn't mean a longer spindle.

  9. #9
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    Quote Originally Posted by kcvpr View Post
    The bigger Q-factor is used to help the crank arms clear the rear suspension on bikes (afaik), like was said above it is the width of the cranks from pedal to pedal. This measurement is also independent of the spindle length, meaning the wider q-factor doesn't mean a longer spindle.
    Thanks for the response. I was wondering what the actual Q factor for those two cranks are, 156 or 166?
    I've checked on SRAM's site but I failed to find those specific specs. Considering a xx1 drivetrain and have run stylo's and s2200 cranks on other bikes.
    Just wondering if anyone may have the specs.
    Thanks.

  10. #10
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    Im getting Focus super bud 1.0 29er bike for the next season and I would like to ask the same question. Does the 156mm Q-factor crank fit in it? Maybe I should just be safe and get the wider version.

  11. #11
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    Quote Originally Posted by PHS View Post
    Thanks for the response. I was wondering what the actual Q factor for those two cranks are, 156 or 166?
    I've checked on SRAM's site but I failed to find those specific specs. Considering a xx1 drivetrain and have run stylo's and s2200 cranks on other bikes.
    Just wondering if anyone may have the specs.
    Thanks.
    Call specialized they should know the q-factor for their own cranks I would hope...
    Quote Originally Posted by tezi View Post
    Im getting Focus super bud 1.0 29er bike for the next season and I would like to ask the same question. Does the 156mm Q-factor crank fit in it? Maybe I should just be safe and get the wider version.
    I would call the manufacturer of the bike you want as well, they should know the minimum q-factor required to clear the suspension . Some people prefer the narrower q-factor for racing because you can spin better (I have only heard this in passing so take it for what it's worth), and the wider q-factor for a more stable feel when the trail points down.

  12. #12
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    The q-factor on the BB30 S-2200 cranks that came on my Stumpy measured out to 168mm.
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