Q-Factor

Dear All,

Clearly Q Factor is a hot topic and we’re sure it’s a debate that will carry on long after the end of our campaign!

We all know that bike fit is an essential part of our performance, injury prevention and comfort and that bike fit is unique to the individual rider. The effects of Q Factor is pretty much unexplored at a scientific level, there are however plenty opinions and herein lay our first and biggest challenge, can we increase the Q Factor without adversely affecting the riders comfort and performance and would the cycling community accept it?

With this in mind we ran initial trials with the Spokes racing team using 20mm Specialized pedal extenders to determine the validity of putting a power meter between the pedal and the crank arm. These initial tests were not run to determine the impact on power only to determine the impact on rider comfort. The feedback from the riders was that the increased Q Factor was noticeable when they first set out but they soon forgot they had the extenders fitted, no one reported increased muscular or joint stress, pain or injury.

The next step was for us to research the impact of increased Q Factor on power. Again limited scientific data¹ existed and what did exist was conflicting with some saying there was a marginal decrease in power and another stating that the increased Q Factor had no impact on power or cycling efficiency. So even in the limited scientific studies the jury is still out! To satisfy ourselves we are running our own internal tests and are working with a university to conduct an independent study on the impact of Q Factor on knee displacement and power, more on this later.

I guess we are challenging the perception that narrower Q Factor is always better, is it really? Where do the biomechanics of most cyclist fall on Q Factor? Do you have a mountain bike and a road bike; do you participate in group indoor cycling? If you do, have you even considered that most road bikes are around 140mm and most mountain bikes and spin bikes around 173mm; you’re jumping between bikes that have variations in Q Factor of ~30mm.

Have you ever even considered Q Factor until now?

¹Published papers

Metabolic and Kinematic Effects of Self-Selected Q factor During Bike Fit – Benedict Xavier Disley and Francois-Xavier Li, April 2013

The effect of Q Factor on gross mechanical efficiency and muscular activation in cycling – Benedict Xavier Disley and Francois-Xavier Li, April 2012

The influence of lateral foot displacement on cycling efficiency and maximal cycling power – Thesis by Sara A Harper May 2014

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