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  1. #1
    viva la v-brakes!
    Reputation: FishMan473's Avatar
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    q-factor of various cranks

    Does anyone know where/how I can find out the q-factor of various MTB cranks?

    I have a "old" set of LX M571 cranks on my touring bike and the pedals are just too far apart for the big road miles that bike gets. I'd like to get another set of MTB cranks with a lower q-factor cause I fee like I'm a duck when I pedal that bike.

    Anyone know a good place to find this info?
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  2. #2
    Vaginatarian
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    here you go
    Attached Images Attached Images
    • File Type: jpg q1.jpg (118.3 KB, 1644 views)
    • File Type: jpg q2.jpg (135.1 KB, 1627 views)

  3. #3
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    another q-factor question

    How can one measure what would be optimum for any given rider?
    What could you measure anatomicaly to determine the q-factor?

    michael
    "Be not afraid of going slowly but only of standing still." - Chinese Proverb

  4. #4
    viva la v-brakes!
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    thanks man! I knew I wasn't crazy the LX cranks are 3 cm wider then my road cranks and 1.2 cm wider then my XTR cranks!

    Where did you find this stuff?
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  5. #5
    Vaginatarian
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    Quote Originally Posted by FishMan473
    thanks man! I knew I wasn't crazy the LX cranks are 3 cm wider then my road cranks and 1.2 cm wider then my XTR cranks!

    Where did you find this stuff?
    here
    someone else posted it here awhile back. prob. on the shimano site somewhere

  6. #6
    viva la v-brakes!
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    Quote Originally Posted by FireDog46
    How can one measure what would be optimum for any given rider?
    What could you measure anatomicaly to determine the q-factor?
    I believe that q-factor should basically be as low as possible. This is because when you walk your stride puts your feet almost one right in front of the other and that is how the muscles, bones and ligaments in your legs are designed to work. Go walk on some surface where you will leave footprints. If you could measure the distance from the center of each foot (where your cleat would be) as you walk that would be the ideal q-factor for you, biomechanically speaking. However, no crank/pedal system will give you something that narrow, it probably wouldn't fit around your chainstays and so forth anyway. So 'as low as possible' is ideal.

    I think.
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  7. #7
    ups and downs
    Reputation: rockyuphill's Avatar
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    It also depends on things like hip width, leg alignment (knock-kneed or bow legged) and whether you rotate your knees and heels in or out while pedaling. If your heels rub on your cranks you will likely have a different optimum Q factor that someone who doesn't rotate their foot when they pedal. Some people need a wider than normal Q factor to reduce the stress on the knee joints.

  8. #8
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    Quote Originally Posted by dan0 View Post
    someone else posted it here awhile back. prob. on the shimano site somewhere
    Does anybody know where I can find an updated version of this document?

    I'm interested in Shimano Saint FC-M815-2 crankset.

  9. #9
    g3h6o3
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    Thanks for undigging this thread, I was searching for those numbers a couple of weeks ago. They are getting hard to find, I don't know if there is an updated version of those documents.
    Check out my SportTracks plugins for some training aid software.

  10. #10
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    Can't understand why Shimano does not publish such data!

  11. #11
    Old school BMXer
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    Shimano does publish the data! But I think only in a printed book for dealers.

    You can find a lot of the newer stuff here: Shimano Framebuilder Info - Pvdwiki
    May the air be filled with tires!

  12. #12
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    Quote Originally Posted by Blaster1200 View Post
    Shimano does publish the data! But I think only in a printed book for dealers.

    You can find a lot of the newer stuff here: Shimano Framebuilder Info - Pvdwiki
    Thanks a lot!! Great info!

    Now I know that the inner width of FC-M815-2 is 156.3 mm. How much is the crank arm thickness? If I knew this figure I'd finally know the Q-factor (outer width) of this crankset.
    Last edited by solitone; 04-20-2012 at 11:53 PM.

  13. #13
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    Crank arm thickness near pedal axle is 16 mm:
    Shimano Saint 10 speed?

    This adds up to a Q-factor of 188.6 for Saint FD-M815-2.

  14. #14
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    Quote Originally Posted by dan0 View Post
    here you go
    I'm seeing black.. Anyones saved these by any chance?

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