Pedal q-factor

Discuss light weight issues concerning road bikes & parts.
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superb
Posts: 103
Joined: Mon Mar 22, 2010 12:31 pm

by superb

Hi

What is the right way to measure pedal q-factor? Is that from the flat face at the crank to the centre of the clip mechanism?

Can anyone tell me pedal q-factor for Shimano PD-9000 and PD-9000E1. Is 52 mm and 56 mm right?
Pedal q factor for Look pedals is 53 and 55 mm? If I want 55 mm q-factor do I have to buy Look q-factor Shims?
Can anyone tell me pedal q-factor for old Mavic Race or Mavic Avenir pedal?

(Such important thing and so hard to find information.)

Thanks

travs
Posts: 3
Joined: Sat Oct 29, 2016 7:14 pm

by travs

Had a quick google and found the following:

http://www.cyclingweekly.co.uk/news/latest-news/what-is-q-factor-and-does-it-make-a-difference-187403
"Q Factor is the distance between the outside of one crank arm to the outside of the opposite crank arm. Although Q Factor has become a universally recognised measurement, other people in the bike trade prefer to use a value for ‘stance width’ — which refers more directly to the distance between feet on the pedals"

It also goes on to state that an average approximate Q-factor for a road bike will be about 150mm.

This article also helps explain a bit too.
http://www.slowtwitch.com/Tech/Stance_Width_2562.html

This is also straightforward in explaining:
http://rideissi.com/articles/stance-wid ... -important

As for the specific pedals, you want to be looking for the spindle-length measurement so see if researching that helps.

superdx
Posts: 511
Joined: Sun Jun 29, 2014 1:27 pm

by superdx

If you have a specific width you need, then adjusting the horizontal position of the cleat is a lot easier than trying to find a pedal which matches your requirements exactly.

Even a different pair of shoes will change your q-factor, it's a pain to setup if you are sensitive to that kind of discrepancy.

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Rick
Posts: 2031
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

I think, but wouldn't argue too strongly, that "Q factor" is the distance between crank-arm faces.
"Stance width" is the distance from pedal-center to pedal-center.
So "Stance width" is a combination of "Q Factor" and spindle length.

The Dura-Ace wide pedals have 55mm spindle, and the regular ones are 51.
But the spindle length of Ultegra is 53. So an Ultegra with 2 pedal washers = the same spindle length as the "wide" Dura ace.
I have both of them and discovered this while trying to set up two different bikes with exactly the same overall stance width.

travs
Posts: 3
Joined: Sat Oct 29, 2016 7:14 pm

by travs

Rick wrote:I think, but wouldn't argue too strongly, that "Q factor" is the distance between crank-arm faces.
"Stance width" is the distance from pedal-center to pedal-center.
So "Stance width" is a combination of "Q Factor" and spindle length.


I think you can argue it a little more strongly seeing as that's what all the articles I found seem to agree Rick

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