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  1. #1
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    What's the Big Deal With Q

    People are always talking about trying to keep the Q factor narrow like they were on some roadieracer bike.

    I have bikes with the Q all over the place and I don't really notice any difference switching back and forth.

    I had to run their widest 6 7/8" spindle on my FS Fat bike to get the Profile cranks, that don't have any dogleg to them, to clear the chain stays and the fat tires and get the rings to line up with the 170mm rear hub, so my Q is huge on that bike. Probably wider than a standard crank with a 100mm shell. But after riding it for a year I don't have any issues and push hard a lot of the time.

    So is this one of those things that people bring to the dirt table from the old days when there were only road bikes and racers wanted pedal clearance for cornering without reevaluating the needs of riding off road? Or is there some bio-mechanical science behind it?

    I would also think, if there is a formula, that it would have something to do with pelvis width and knee angle or something like that and not be the same for all, even though everyone that talks about it wants to keep it narrow.
    No it never stops hurting, but if you keep at it you can go faster.

  2. #2
    Fat-tired Roadie
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    It's nice for you that you don't notice.

    When I'm on something that's not varying much, I do. Like a long fire road climb, or on the rare occasion that my MTB sees asphalt. The wider tread of my MTB doesn't bother me enough in the context in which I actually use it for me to spend money getting a new crank with a narrower Q. But if I could magically have one, hell yeah I'd take it.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
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    Some people care about Q, others don't. Some like wide, some like narrow. (Crank length is similar.) If you don't notice/care, you're lucky!!!

    I've so far avoided fatbikes as I'm 100% sure the massive Q would destroy my knees; for me 160mm is higher than comfortable. The lower the better, for me.

    What anyone likes or can tolerate really depends on individual biomechanics, and AFAIK there are no good explanations of why certain things suit some people but not others. As with everyhting else to do with fit, YMMV.

  4. #4
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    When I go from my narrow Q to wider I notice a difference. But I can also notice a 2mm change in seat position too (and it will make a difference to my pedaling efficiency).

    Some can and some can't. Be thankful you can adapt with no problems and don't notice anything.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  5. #5
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    Some research has shown an improvement in efficiency with a lower Q-factor but there was a movement some years back that claimed a much wider Q was more ergonomic and a better fit for human physiology.

    I'm sure there is an ideal Q, and it is probably a little different for every person depending on their size, bone structure, whether they pronate, supinate, etc.etc.etc.

    Personally I've never fretted over it and don't notice any difference between a slightly wider or narrower Q.

  6. #6
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    Quote Originally Posted by J.B. Weld View Post
    Some research has shown an improvement in efficiency with a lower Q-factor but there was a movement some years back that claimed a much wider Q was more ergonomic and a better fit for human physiology.

    I'm sure there is an ideal Q, and it is probably a little different for every person depending on their size, bone structure, whether they pronate, supinate, etc.etc.etc.

    Personally I've never fretted over it and don't notice any difference between a slightly wider or narrower Q.
    I actually would like a little wider Q....I run XT HT II cranks.....

    Feels like my knees and legs are pointed in a little bit and things would be better if my feet where just a little farther apart.

  7. #7
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    Quote Originally Posted by J.B. Weld View Post
    Some research has shown an improvement in efficiency with a lower Q-factor but there was a movement some years back that claimed a much wider Q was a better fit for human psychology.
    Fixed it for you!

    More seriously, various Olympic track bikes over the years have used extremely low Qs and I think Phil Wood offer BBs to suit, not that these will fit any standard frame:

    "Standard spindle lengths range from 70mm to well over 155mm. The spindles are sold as either a plain spindle (for use with press-fit style bottom bracket shells) or assembled in a cartridge with bearings. Cartridge widths are available for bottom bracket shells in 63, 68, 73, or 100mm with any spindle length to accommodate the target frame. Custom spindle lengths and cartridge widths are available upon special request." from: Phil Wood & Co.

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