[Q-factor] List of fat bike compatible cranks- Mtbr.com
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  1. #1
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    [Q-factor] List of fat bike compatible cranks

    I am not very well versed in bike tech and terminology so please excuse any errors in this or any of the latter posts!

    Hello,

    given this info is all over the forum but I haven't found one thread where everything is in place - let's start a list with cranks suitable for fat bikes that allow for a 65/75mm chainline while still keeping the Q-factor as low as possible to get the ball rolling!


    See here for the Q-factor relevant parts of the drivetrain:

    Cranks #2
    Spindles #3
    Spiders and chainrings #4
    reserved #5
    reserved #6
    Last edited by El_Topo; 06-09-2019 at 09:49 AM.

  2. #2
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    Cranks:

    All values based on a 170mm spindle resulting in a 75mm chainline, extrapolate from that value to a 190mm or 150 or any other spindle (all values in millimetres):

    Brand Name Q-factor Arm clearance Source Notes
    Canondale SI ? ?
    Cannondale SI sl ? ?
    Raceface Aeffect 209 (same as Next R?) ? extrapolated from Voytek's specs
    Raceface Next SL 203 76 RF PDF flipped chainring
    Raceface Next R 209 78 RF PDF flipped chainring
    Raceface Turbine 213 83 RF PDF flipped chainring
    RF PDF flipped chainring
    SRAM table ? ?
    Last edited by El_Topo; 06-09-2019 at 10:23 AM.

  3. #3
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    Spindles:


    Brand Length System Notes
    Cannondale 160 ISIS for 2016-2017 Fat CAAD
    Cannondale 166 ISIS for 2018-? Fat CAAD
    Raceface 174.5 ISIS only available for OEMs (=Unobtainium)
    Last edited by El_Topo; 06-09-2019 at 09:00 AM.

  4. #4
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    Spiders and chainrings:


    Brand Name Notes
    Wolftooth CAMO allows chainline adjustment

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    Reserved.

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  7. #7
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    I am not very well versed in bike tech and terminology so please excuse any errors in any of the former posts but I felt someone needed to get the ball rolling on this subject.

    Feel free to add anything you deem worth it, correct me if I am wrong somewhere (quite likely) or whatever comes to your mind regarding this subject but please keep your replies concise to keep this thread compact and assesable, meaning if you want to add info on different cranks and their specs, collect them into a single post before replying.

    Please help by posting more cranks and their respective QFs with a standard 170mm spindle and if possible link to manufacturers spec sheets so all entries can be verified.

    I was able to find SRAM's specs for their 2017-2019 MTB crank lineup but have a hard time extracting the necessary info from them, feel therefore free to read them and post your findings.
    I as well found this, where they have nice table with QFs for SRAM cranks, if nobody objects I will put them into the table above.

    Is there a standard on how a crank is measured that I should have in the tables above?

    Like this:




    Thanks in advance!
    Attached Thumbnails Attached Thumbnails [Q-factor] List of fat bike compatible cranks-gh5gkr5.png  

    Last edited by El_Topo; 06-09-2019 at 10:03 AM.

  8. #8
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    Otso uses a Raceface Next SL and can get the Q factor down to 183mm. They are aided in getting such a narrow Q by using there Wolftooth Camo spider and rings.

  9. #9
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    Thanks for your reply, BlueCheesehead.

    Quote Originally Posted by BlueCheesehead View Post
    Otso uses a Raceface Next SL and can get the Q factor down to 183mm. They are aided in getting such a narrow Q by using there Wolftooth Camo spider and rings.
    I know about the Voytek but they do so with a 150mm (149.5mm to be precise) spindle to get a 65(-ish)mm chainline so it is the same as a 75mm chainline with a 170mm (169.5mm to be precise) spindle, isn't it?
    I chose the 170mm spindle as a baseline because that seems to be the most common, as described in post #2 you can deduct any other QF from that if I am not mistaken.

    I think the question for this topic is, what is their chainline at the chainring side? Is it 65mm like Raceface's flipped chainring or maybe a few millimetres more? If it is more one might get one of those Cannondale 160mm spindles as mentioned in post #3, add 5mm spacers to the 83mm BB (is that possible?), add a small spacer of 2-3mm to the bolt that connects the CAMO spider to their chainring and you'd have a chainline of approximately 75mm with a 193mm QF!
    Of course heel clearance to the chain might be an issue if you push the chainline out even further.

    Obviously this would need a custom frame design.
    Last edited by El_Topo; 06-10-2019 at 03:10 AM.

  10. #10
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    Sorry, I guess I miss the point of putting together a supposed comprehensive list of parts the affect Q factor, yet limit the one thing that has the biggest impact to one size. It seems you could have omitted post 3 all together since we are to assume it is fixed at 170mm.

    Lack of response to the thread may be an indication of lack of understanding of what you really intend to accomplish...or perhaps just general apathy.

  11. #11
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    Quote Originally Posted by BlueCheesehead View Post
    Sorry, I guess I miss the point of putting together a supposed comprehensive list of parts the affect Q factor, yet limit the one thing that has the biggest impact to one size. It seems you could have omitted post 3 all together since we are to assume it is fixed at 170mm.
    I don't omit it, post #3 is there for a reason.
    If someone tells how to lay out a table that can be read easily (not like those gazillion values in shown in post #7) that excludes the spindle length altogether I am happy to do so.
    I think it is pointless to list the QF for every crank and spindle combination (especially if I don't even know what kind of exotic spindle lengths are out there) if you can work out the QF of your combination with the value provided in the table.
    Deducting that a 203mm QF for the Next SL cranks with a 170mm spindle means 183mm QF with the same cranks and a 150mm spindle shouldn't be too hard, or is it?
    I mean this as a serious question, am I missing something obvious?


    Quote Originally Posted by BlueCheesehead View Post
    Lack of response to the thread may be an indication of lack of understanding of what you really intend to accomplish...or perhaps just general apathy.
    As mentioned in the opening post and one of the latter ones, I don't know enough about bike tech to be sure my table is thought out well but I am happy to change/augment anything that you or another member deems worthy to add.
    If it is just apathy, I really don't know what to do...


    EDIT: How about QF = X ("crank value") + Y (spindle length) ?
    Example: for the Next SL it would be X(170)+33=203mm

    Which would translate to:


    Brand Model Q-factor Arm clearance
    Raceface Next SL X+33 (X/2)-9
    Last edited by El_Topo; 06-11-2019 at 10:17 AM.

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