Author Topic: Q Factor  (Read 183 times)

mickeg

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Q Factor
« on: June 03, 2018, 12:35:30 PM »
I saw a short article on knee pain.  I have not had knee pain since I stopped standing on the pedals to accelerate from a stop or to power up hills.  But, I read the article anyway and found it to be quite interesting. 
https://www.roadbikerider.com/knee-pain-knee-alignment-and-pedal-stance-width/

Some of you may recall that I described how my Nomad chainline was intentionally off by about 5 mm because I wanted the Q Factor on my Rohloff bike to be about the same as the Q Factor on my derailleur bikes.  Thus, my Nomad bottom bracket spindle is about 10 mm shorter than would be ideal for proper chain line.

They described knee pain from pedal stance width that is too narrow.  I do not know if the opposite could cause knee pain, but logic suggests that it probably could. 

In my case with my particular crankset (not a Thorn), if I had set up my Rohloff bike to have an ideal chainline, I wonder if that might have caused knee pain from too wide a pedal stance?  Perhaps fortunately I did not find out.

martinf

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Re: Q Factor
« Reply #1 on: June 03, 2018, 05:24:21 PM »
They described knee pain from pedal stance width that is too narrow.  I do not know if the opposite could cause knee pain, but logic suggests that it probably could. 

I think it is a bit like saddles - people seem to like different widths.

When I was running 170 mm cranks I preferred the narrowest possible width, often using TA Cyclotourist cranks on short axles. My old derailleur tourer has a Q-factor of 138 mm, triple chainring on a short axle and extra-narrow spacers between the outer and middle rings to enable the inner ring to clear the chainstay.

With the 150 mm cranks I now use I don't mind a wider Q-factor. I was happy on my last big tour in 2011 with Thorn triple cranks and a Q-factor of 163 mm.

PH

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Re: Q Factor
« Reply #2 on: June 04, 2018, 10:59:18 PM »
They described knee pain from pedal stance width that is too narrow.  I do not know if the opposite could cause knee pain, but logic suggests that it probably could. 

I think it is a bit like saddles - people seem to like different widths.

Indeed, not only preferences, but also tolerances.  I'm duck footed so need a wide spacing to avoid heel strike on the chainstay. Components and set up are chosen with that as the first priority and as a consequence have different Q factors, I simply don't notice.