If you've been browsing our pedals you've probably noticed we bang on about Q-Factor a fair bit. So here's a quick explanation.
Essentially Q-Factor is the distance between the pedal attachment points on the crank arms, also referred to as Tread. It could also be described as the width of your crankset. This affects your stance, if you've ever been snowboarding think of it as the same thing, essentially the distance between your feet.
Now, technically pedals have nothing to do with Q-Factor (imagine really wide pedals in the above diagram, the Q-Factor would remain unchanged), this is purely a crank measurement, but people have come to adopt the phrase to mean the same thing. And in practice, all we really care about is how far apart your feet are (stance).
So in reality, pedals with a larger "Q-Factor" will give you a wider stance, and vice versa.
In road riding, a narrower stance can help with aerodynamics, but it also has to suit the individual's body ergonomics. It could also be considered that the wider the Q-Factor, the more force is required through the bars to keep the bike from tipping sideways. 10 years ago this might have been noticeable, but with mountain bike bars commonly reaching 800mm+ this effect is pretty negligible.
In mountain biking we don't care about aerodynamics as much, so it's more a question of what feels best. Some riders like narrow, some like wide (Ian for example, who actually has a custom spacer made to widen his stance), and some can't even tell the difference.
Now you know! Check out some pedals armed with this knowledge!