1 (or 2) mm Q-factor offset
07-28-23, 02:31 AM
#1
Newbie
Thread Starter
Join Date: Jul 2023
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
1 (or 2) mm Q-factor offset
Hi!
I ride a road bike with an older Shimano 105 5700 groupset. I have an option to add a single side 4iii in-crank power meter installed in a younger 105 FC-7000 left crank.
As I found out in the web my 105 FC-5700 crakset has a Q factor of 144mm and a 105 FC-7000 crakset has a Q factor of 146mm. So there is a 2mm difference in a crankset Q factor and so I assume 1mm on just the left crank.
Would I notice this offset or even worse - would it harm my posture/knees/hips?
Thank you!
BR, Peter
I ride a road bike with an older Shimano 105 5700 groupset. I have an option to add a single side 4iii in-crank power meter installed in a younger 105 FC-7000 left crank.
As I found out in the web my 105 FC-5700 crakset has a Q factor of 144mm and a 105 FC-7000 crakset has a Q factor of 146mm. So there is a 2mm difference in a crankset Q factor and so I assume 1mm on just the left crank.
Would I notice this offset or even worse - would it harm my posture/knees/hips?
Thank you!
BR, Peter
07-28-23, 07:21 AM
#2
Senior Member
Join Date: Jan 2009
Location: San Diego, CA
Posts: 3,700
Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 850 Post(s)
Liked 1,081 Times
in
754 Posts
Most people won't notice but I am one who does causing some knee pain in my senior years. Easily corrected by just moving your cleats or pedal axle washers if needed. Before doing any adjustments, go for a long ride and often your body will tell you if any adjustments are needed or not.
07-28-23, 04:28 PM
#3
Senior Member
Join Date: Apr 2016
Posts: 1,286
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 520 Post(s)
Liked 461 Times
in
353 Posts
As I found out in the web my 105 FC-5700 crankset has a Q factor of 144mm and a 105 FC-7000 crakset has a Q factor of 146mm. So there is a 2mm difference in a crankset Q factor and so I assume 1mm on just the left crank.
Would I notice this offset or even worse - would it harm my posture/knees/hips?
Would I notice this offset or even worse - would it harm my posture/knees/hips?
07-29-23, 07:32 PM
#4
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,824
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5840 Post(s)
Liked 2,673 Times
in
1,488 Posts
You're assuming that the original Q factor was perfect and any change would be detrimental.
Equally plausible is that the original Q was off, and the change would be an improvement.
People are different, and not built to precision tolerances. So "optimal" Q factor would depend on things like hip width and all the small variations in legs and feet. As such, there's plenty of latitude, and the only difference that 2mm would make is that you now know, and are free to fret over it.
Equally plausible is that the original Q was off, and the change would be an improvement.
People are different, and not built to precision tolerances. So "optimal" Q factor would depend on things like hip width and all the small variations in legs and feet. As such, there's plenty of latitude, and the only difference that 2mm would make is that you now know, and are free to fret over it.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
Likes For FBinNY:
07-30-23, 01:17 PM
#5
Senior Member
Join Date: Aug 2009
Posts: 1,842
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 512 Post(s)
Liked 657 Times
in
389 Posts
If you are putting the L crankarm on the 5700 crankset, the difference (assuming there is actually one) on the Q factor is going to be 1 mm, doubtful that would make a difference or even be noticed, but if you are anal about it, it could easily be adjusted at the cleat or on the arm.
07-30-23, 01:28 PM
#6
Senior Member
Join Date: Jul 2015
Location: NW Oregon
Posts: 2,978
Bikes: !982 Trek 930R Custom, Diamondback ascent with SERIOUS updates, Fuji Team Pro CF and a '09 Comencal Meta 5.5
Mentioned: 15 Post(s)
Tagged: 1 Thread(s)
Quoted: 1299 Post(s)
Liked 741 Times
in
536 Posts
you're worrying about a spark plug gap of change? less than 1/8" difference.
seriously.
seriously.
Likes For maddog34:
07-30-23, 02:55 PM
#7
I'm good to go!
Join Date: Jul 2017
Location: Mississippi
Posts: 15,082
Bikes: Tarmac Disc Comp Di2 - 2020
Mentioned: 51 Post(s)
Tagged: 0 Thread(s)
Quoted: 6252 Post(s)
Liked 4,852 Times
in
3,344 Posts
You're reminding me of the Benson & Hedges cigarette commercial that were probably before your time.
If you do notice a difference, then play with the angle of your cleats and other stuff before thinking your build requires an exact q-factor.
Welcome to BF!
If you do notice a difference, then play with the angle of your cleats and other stuff before thinking your build requires an exact q-factor.
Welcome to BF!
Last edited by Iride01; 07-30-23 at 03:04 PM.
07-30-23, 03:20 PM
#8
Senior Member
Join Date: Jan 2005
Location: Baltimore, MD
Posts: 5,428
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 2512 Post(s)
Liked 2,993 Times
in
1,699 Posts
If, like most of us here, you've owned or ridden a number of bikes in your lifetime, chances are that you've unknowingly experienced differences in Q factor of 5 or even 10 mm without noticing.
Q factor became a fear-monger's topic when Rivendell was buying up new-old-stock, discontinued cranksets and figured out that scaring people about wide pedal stances was a great way to move some inventory. Like their dismissal of "point-and-click" indexed shifting after they bought hundreds of out-of-production friction shifters.
Q factor became a fear-monger's topic when Rivendell was buying up new-old-stock, discontinued cranksets and figured out that scaring people about wide pedal stances was a great way to move some inventory. Like their dismissal of "point-and-click" indexed shifting after they bought hundreds of out-of-production friction shifters.
Likes For Trakhak:
