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KOPS and small LLD

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KOPS and small LLD

Old 05-15-24, 12:04 AM
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KOPS and small LLD

Is it correct to assume that when I measure with the "Kops" method and hang a plumb line from under the kneecap when the crank arm is at three o'clock but the plumb line on the left leg comes far in front of the pedal spindle but on the right leg falls right over the pedal spindle and I have a known small leg length difference should I then try to move the cleat on the left side further back?
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Old 05-15-24, 08:43 AM
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KOP's supposedly tells you where your saddle should be. Not where you put the cleat.

While many of us don't put a lot of faith in KOP's to have it override other considerations of bike fit. It might be useful to know where that plumb bob is and use it to consider or reconsider other aspects of the riders position and the bike's particulars.

My thoughts at the moment is whether you have a unusually large amount of saddle setback or is your crank arm unusually long?
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Old 05-15-24, 10:04 AM
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Originally Posted by hsea17
Is it correct to assume that when I measure with the "Kops" method and hang a plumb line from under the kneecap when the crank arm is at three o'clock but the plumb line on the left leg comes far in front of the pedal spindle but on the right leg falls right over the pedal spindle and I have a known small leg length difference should I then try to move the cleat on the left side further back?
hsea17
Fore/Aft cleat placement mostly affects the foot 'lever' and will affect muscle engagement in the entire pedal stroke, especially lowerleg/calf engagement, but really all the muscles involved. I always refer to KOPS as a good start point...
I also use the prominance of the Tibial Tuberosity as the 'plumbline' drop point, which can be fell on leg outsid, just below edge of Knee Cap - consistent point and takes away any variance due to knee cap/flesh/ other variables.
Many of us have leg length differences, so we 'compensate'. For some, the difference requires real mediation... For most of us, a 'compromise' between legs, for both saddle height, setback AND cleat fore/aft placement works - over the many miles we ride...
I do think that a slow buildup of effort after making significant changes, over days of riding, is the best way to allow the body to adapt to new dynamics.
Cleat Rotation may be the most difficult for most riders to get to their optimum, and can be a big contributor to pedaling or leg issues... I have my own methods which have worked great for many decades... My cleats each have a slightly different rotation, and cleat/clamp float seems to handle any variance I might have.
So no 'definitive' from me. I don;t think there's a 'correct'.
But I would re-check everything - among other things a slight tilt to the hips while doing this, can have a big effect...
Ultimately, my tendency, for variations in that drop line, would be to again compromise...and see how it goes over some days, varied efforts of riding...
We're all in a much better place since cleats are very moveable, compared to having t nail them on Back in the Day...
Ride On
Yuri
'LLD' = Lower Leg Dimension or difference?
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Old 05-16-24, 04:58 AM
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Originally Posted by Iride01
KOP's supposedly tells you where your saddle should be. Not where you put the cleat.

While many of us don't put a lot of faith in KOP's to have it override other considerations of bike fit. It might be useful to know where that plumb bob is and use it to consider or reconsider other aspects of the riders position and the bike's particulars.

My thoughts at the moment is whether you have a unusually large amount of saddle setback or is your crank arm unusually long?
Thank you for replying. I have not an usually large amount of setback (I think) but a frame which I have come to have a longer top tube / seat tube /head tube compared to previous bike but actually are both a M size. Crank arm is 172.5.
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Old 05-16-24, 05:04 AM
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Originally Posted by cyclezen
Fore/Aft cleat placement mostly affects the foot 'lever' and will affect muscle engagement in the entire pedal stroke, especially lowerleg/calf engagement, but really all the muscles involved. I always refer to KOPS as a good start point...
I also use the prominance of the Tibial Tuberosity as the 'plumbline' drop point, which can be fell on leg outsid, just below edge of Knee Cap - consistent point and takes away any variance due to knee cap/flesh/ other variables.
Many of us have leg length differences, so we 'compensate'. For some, the difference requires real mediation... For most of us, a 'compromise' between legs, for both saddle height, setback AND cleat fore/aft placement works - over the many miles we ride...
I do think that a slow buildup of effort after making significant changes, over days of riding, is the best way to allow the body to adapt to new dynamics.
Cleat Rotation may be the most difficult for most riders to get to their optimum, and can be a big contributor to pedaling or leg issues... I have my own methods which have worked great for many decades... My cleats each have a slightly different rotation, and cleat/clamp float seems to handle any variance I might have.
So no 'definitive' from me. I don;t think there's a 'correct'.
But I would re-check everything - among other things a slight tilt to the hips while doing this, can have a big effect...
Ultimately, my tendency, for variations in that drop line, would be to again compromise...and see how it goes over some days, varied efforts of riding...
We're all in a much better place since cleats are very moveable, compared to having t nail them on Back in the Day...
Ride On
Yuri
'LLD' = Lower Leg Dimension or difference?
Thanks for replying. I have now moved the cleat back approx. 2mm on left shoe and if it does not work as hoped I will try to balance it between both legs /cleats.
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Old 05-21-24, 11:23 PM
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Originally Posted by hsea17
Thanks for replying. I have now moved the cleat back approx. 2mm on left shoe and if it does not work as hoped I will try to balance it between both legs /cleats.
hsea17
hope you didn't misinterpret my post. I didn't mean to suggest differing fore'aft cleat locations from one foot to the other.
Actually, I generally suggest picking a 'spot', and setting both shoes to that spot, The adjustment for each foot regarding 'variable', is for cleat rotation.
Whether you want to pedal with the cleat up near the toes, or under the middle of the foot, just pick a consistent spot and work with that - same fore/aft on each foot/shoe.
Ride On
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Old 05-21-24, 11:53 PM
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I'd be inclined to use the same cleat fore and aft position for each shoe but place the appropriate shim between between cleat and sole for your shorter leg. (My right leg is a 1/2" (12mm) shorter. I use a 1/4" (6mm) shim.) Cleats set same distance back left and right. I did this soon after a PT identified my shorter leg; I'd been compensating and staying oblivious all my life. 1/2 the leg difference seemed right to me and felt right on the bike immediately. Showed my shoe to my PT. She said that was exactly what she'd have told me to do.)

My worry with different cleat positions is running into foot injuries. The cleat further forward stresses that foot and ankle more (greater leverage).
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Old 05-22-24, 02:58 AM
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I read somewhere in an online bike magazine in an article / interview with a world famous bike fitter (I think it was from a fit institute in Colerado) who said something like, if the LLI was less than 6mm he didn't use a shim but instead moved the cleat on the side with the short leg forward on the shoe sole 1-2mm and that you could move the cleat backwards on the longest leg to get the same effect, and that you rarely need to compensate for the entire LLI.

It's something as above that I have tried to do now and somewhat the plumb line now is nearer the pedal axle. However, I'm still in for more testing and missteps but hope to get it more or less right eventually.

I consider a Retul bike fit which also nowadays is available in this part of the world, but I am skeptical as to whether it will help as the last one I had more or less positioned me as I had always positioned myself on the bike. Now it's been 12 years so probably some more changes with me as I age.
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