Leg Length and Left/Right Unequal Power Meter Balance
#26
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All,
Since we last talked, here's what I've done. I used one of these cleat risers on my right foot.
https://www.amazon.com/dp/B00BP52Y4Y...roduct_details
I went on four rides totaling over 75 miles.
1) August 22, 2022
17 miles, rolling hills and flats
Left/Right Power Balance = 54/46
2) August 24, 2022
17 miles, rolling hills and flats
L/R = 54/46
3) August 27, 2022
21 miles, a few more rolling hills and flats
L/R = 55/45
4) August 31, 2022
On this ride, I removed the cleat riser from my right foot
21 miles, a few more rolling hills and flats
L/R = 55/45
I've come to 2 conclusions
1) Focusing on L//R power balance doesn't matter for an amateur.
2) The Shimano dual-sided Dura Ace crank power meters are inherently inaccurate on L/R balance and total power output (lower) when compared to other meters. They are consistent within themselves, however. Shimano knows this but won't admit it. Interestingly, the drive side strain sensor is located closer to the bottom bracket than is the non-drive side strain sensor. You would think the L/R imbalance could be compensated for through firmware.
I base conclusion 1 one some of the posts above and conclusion 2 based on some research I've done such as
From DC RainMaker and Bike Radar
https://www.dcrainmaker.com/2018/04/...th-review.html
https://www.bikeradar.com/reviews/tr...-meter-review/
https://www.dcrainmaker.com/2022/05/...g-metrics.html
From Shane Miller GPLama
Hopefully this has been of some help to others. Thank you all for your input.
Glenn Atkins
Since we last talked, here's what I've done. I used one of these cleat risers on my right foot.
https://www.amazon.com/dp/B00BP52Y4Y...roduct_details
I went on four rides totaling over 75 miles.
1) August 22, 2022
17 miles, rolling hills and flats
Left/Right Power Balance = 54/46
2) August 24, 2022
17 miles, rolling hills and flats
L/R = 54/46
3) August 27, 2022
21 miles, a few more rolling hills and flats
L/R = 55/45
4) August 31, 2022
On this ride, I removed the cleat riser from my right foot
21 miles, a few more rolling hills and flats
L/R = 55/45
I've come to 2 conclusions
1) Focusing on L//R power balance doesn't matter for an amateur.
2) The Shimano dual-sided Dura Ace crank power meters are inherently inaccurate on L/R balance and total power output (lower) when compared to other meters. They are consistent within themselves, however. Shimano knows this but won't admit it. Interestingly, the drive side strain sensor is located closer to the bottom bracket than is the non-drive side strain sensor. You would think the L/R imbalance could be compensated for through firmware.
I base conclusion 1 one some of the posts above and conclusion 2 based on some research I've done such as
From DC RainMaker and Bike Radar
https://www.dcrainmaker.com/2018/04/...th-review.html
https://www.bikeradar.com/reviews/tr...-meter-review/
https://www.dcrainmaker.com/2022/05/...g-metrics.html
From Shane Miller GPLama
Hopefully this has been of some help to others. Thank you all for your input.
Glenn Atkins
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the answer to this seems glaringly simple to me. drive side is on the right. your right leg will obviously have an easier time putting down power as a result. your left leg will have to compensate for this by putting out more power to match. mystery solved.
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Did you read my post #26 right above yours? A glaringly simple mystery already solved.
Regards
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Glenn, how would I find out if one leg is longer than the other? Is there a test for that? My L/R is something like 45-48 on the left and as high as 55 on the right.
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I got it in my head that I may have a leg length difference when I consistently noticed my left/right power imbalance. It took a concentrated pedaling effort, which felt unnatural, to even out the power balance. I put a cleat riser (not an angled shim) under my right cleat and had no change so I took it out.
I did some research and considered the posts above and came to the realization that the L/R balance doesn't matter for an amateur and that Shimano is aware, and has been for a while, about the balance issue in their crank-based, two-sided meters.
A confounding factor for me was that I have always had left, outside toe numbness and hot-foot. But never in my right toes/foot - only the left. I also have peripheral neuropathy in both lower legs, not diabetes related. I thus began a journey to see if I could fix the numbness and hot foot.
1) had the bike fit, including custom Specialized insoles (done in 2020)
2) shimmed my left cleat (done in 2020)
a) i use one glove size above my normal. for example i use extra large instead of large
b) i use one shoe size above my normal size
3) more recently shimmed my right cleat (2022)
4) tried and then removed my right cleat riser (again, not a angled shim) (2022)
5) moved both cleats to the rear as far as I could (2022)
6) just within the last week went from a 138mm saddle to a 155mm to a 165mm saddle (2022)
7) just within the last week moved my seat forward 15mm, yes I know that's a lot even though it's only about 6/10 of an inch, but I'm relatively older and don't yet have enough flexibility (2022). I've been off the bike for a year - some from laziness but almost six months due to a severe right calf injury unrelated to cycling
I may raise my saddle some to compensate for its move forward, just don't yet know how much to move it.
What clearly helped the most with outer toe numbness and hot foot in my left foot was moving the cleats completely to the rear. Second best was shimming the left cleat and the bike fit. That's where the left shim came from. The fit mostly took weight off my hands.
I did 18 miles last night with all the above in place. Problems largely resolved even though it's a sample size of one.
Next on the list of things to try if the above don't continue to work include:
https://mid-foot-cycling.com/
https://www.g8performance.com/insole...ievers-bundle/
I do not have any affiliation to any product mentioned in this post.
Glenn
Last edited by GAtkins; 09-13-22 at 09:25 AM. Reason: Edited to correct metric measurement in item 7 from 150mm to 15mm
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Why is the idea of using a shorter crank arm for the shorter leg frowned upon (vs a shim)?
The problem I had when I tried a shim was that the stack height really made it hard to tolerate, whereas the shorter leg only bothers me if the saddle is at the high/optimum for the longer leg. (This difference is small enough that I didn't notice it existed until my bike fitter/framebuilder mentioned it to me, but I can feel one leg can be over-extended when the other is comfortable.)
The problem I had when I tried a shim was that the stack height really made it hard to tolerate, whereas the shorter leg only bothers me if the saddle is at the high/optimum for the longer leg. (This difference is small enough that I didn't notice it existed until my bike fitter/framebuilder mentioned it to me, but I can feel one leg can be over-extended when the other is comfortable.)
Ideally, you'd want both legs to be doing the same amount of work. Generally the way to do this, is to align the work to where the rider happens to be. I.e., a shim.
Though there is a bunch of different ways one limb can be different than the other. So, there are undoubtedly cases where a different crank arm length could be appropriate. But, that would between that person & their licensed doctor professional based on that persons particulars.
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#32
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I had a bike fit at Retul in Boulder a couple of years ago and they didn't mention that I had a discrepancy. I forget exactly how they measured it.
I got it in my head that I may have a leg length difference when I consistently noticed my left/right power imbalance. It took a concentrated pedaling effort, which felt unnatural, to even out the power balance. I put a cleat riser (not an angled shim) under my right cleat and had no change so I took it out.
I did some research and considered the posts above and came to the realization that the L/R balance doesn't matter for an amateur and that Shimano is aware, and has been for a while, about the balance issue in their crank-based, two-sided meters.
A confounding factor for me was that I have always had left, outside toe numbness and hot-foot. But never in my right toes/foot - only the left. I also have peripheral neuropathy in both lower legs, not diabetes related. I thus began a journey to see if I could fix the numbness and hot foot.
1) had the bike fit, including custom Specialized insoles (done in 2020)
2) shimmed my left cleat (done in 2020)
a) i use one glove size above my normal. for example i use extra large instead of large
b) i use one shoe size above my normal size
3) more recently shimmed my right cleat (2022)
4) tried and then removed my right cleat riser (again, not a angled shim) (2022)
5) moved both cleats to the rear as far as I could (2022)
6) just within the last week went from a 138mm saddle to a 155mm to a 165mm saddle (2022)
7) just within the last week moved my seat forward 15mm, yes I know that's a lot even though it's only about 6/10 of an inch, but I'm relatively older and don't yet have enough flexibility (2022). I've been off the bike for a year - some from laziness but almost six months due to a severe right calf injury unrelated to cycling
I may raise my saddle some to compensate for its move forward, just don't yet know how much to move it.
What clearly helped the most with outer toe numbness and hot foot in my left foot was moving the cleats completely to the rear. Second best was shimming the left cleat and the bike fit. That's where the left shim came from. The fit mostly took weight off my hands.
I did 18 miles last night with all the above in place. Problems largely resolved even though it's a sample size of one.
Next on the list of things to try if the above don't continue to work include:
https://mid-foot-cycling.com/
https://www.g8performance.com/insole...ievers-bundle/
I do not have any affiliation to any product mentioned in this post.
Glenn
I got it in my head that I may have a leg length difference when I consistently noticed my left/right power imbalance. It took a concentrated pedaling effort, which felt unnatural, to even out the power balance. I put a cleat riser (not an angled shim) under my right cleat and had no change so I took it out.
I did some research and considered the posts above and came to the realization that the L/R balance doesn't matter for an amateur and that Shimano is aware, and has been for a while, about the balance issue in their crank-based, two-sided meters.
A confounding factor for me was that I have always had left, outside toe numbness and hot-foot. But never in my right toes/foot - only the left. I also have peripheral neuropathy in both lower legs, not diabetes related. I thus began a journey to see if I could fix the numbness and hot foot.
1) had the bike fit, including custom Specialized insoles (done in 2020)
2) shimmed my left cleat (done in 2020)
a) i use one glove size above my normal. for example i use extra large instead of large
b) i use one shoe size above my normal size
3) more recently shimmed my right cleat (2022)
4) tried and then removed my right cleat riser (again, not a angled shim) (2022)
5) moved both cleats to the rear as far as I could (2022)
6) just within the last week went from a 138mm saddle to a 155mm to a 165mm saddle (2022)
7) just within the last week moved my seat forward 15mm, yes I know that's a lot even though it's only about 6/10 of an inch, but I'm relatively older and don't yet have enough flexibility (2022). I've been off the bike for a year - some from laziness but almost six months due to a severe right calf injury unrelated to cycling
I may raise my saddle some to compensate for its move forward, just don't yet know how much to move it.
What clearly helped the most with outer toe numbness and hot foot in my left foot was moving the cleats completely to the rear. Second best was shimming the left cleat and the bike fit. That's where the left shim came from. The fit mostly took weight off my hands.
I did 18 miles last night with all the above in place. Problems largely resolved even though it's a sample size of one.
Next on the list of things to try if the above don't continue to work include:
https://mid-foot-cycling.com/
https://www.g8performance.com/insole...ievers-bundle/
I do not have any affiliation to any product mentioned in this post.
Glenn
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165 mm vs. 172 mm is a 4% difference.
#34
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Thanks, I had a Retul fit in July. They did not make any measurements of my body. I suspect I have some sort of imbalance in my torso because I sit a little cockeyed on the saddle and my left hamstring will hurt on a harder effort. I don't feel like wasting more money. Thanks for your input. I do think a tru 45/55 imbalance is a problem for me but do not know the solution.
And, do you find yourself pushing yourself back toward the rear of the saddle?
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I did feel like I was "oozing" forward on the saddle prior to the moving the saddle forward, yes. Nothing about my pedaling compared to most on the forum could be considered "powerful."
Yes, I did find myself pushing back toward the rear of the saddle to get the sit-bones just right fore and aft before I moved the saddle forward. Current saddle tilt is negative 2 degrees. Think I should make that flat?
Thoughts, ideas?
Thanks.
Glenn
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One approach to the oozing is to move the saddle forward so that "after the ooze" your sitbones are in the right places on the saddle. Another is to gently start to raise the nose of the saddle to have gravity add a little force in the rearward direction, acting on your pelvis to keep it from forward motion, however slow. As a test, sliding the saddle forward is good since it shows that you are not on the saddle as you should be.
By "negative 2 degrees" do you mean that the nose is up or down?
In the current saddle position, are you tending to slide forward as you pedal? If so I would gradually move the saddle nose up. This is where a micro-adjusting seat post with two bolts, not just a single clamp bolt with the mount rotation being limited by a ratchet, helps a lot to find the best spot. The best spot might be between ratchet points. If you raise the saddle nose slowly you should feel the pressure on your underside moving. The pressure should be on your sitbones and not of significant magnitude in front ot them, and you should not be using your legs to hold yourself in place. You should be sitting on your saddle with stability with your back straight up and with your pelvis and back rotated forward to reach the hoods and preferably the drops.
For me this last paragraph is really important in fitting myself. It works for Mrs. Road Fan as well and for a tri-winning neighbor lady whom I helped once. It also mirrors a lot of what Carbonfiberboy recommends, due to his long experience and his research.
By "negative 2 degrees" do you mean that the nose is up or down?
In the current saddle position, are you tending to slide forward as you pedal? If so I would gradually move the saddle nose up. This is where a micro-adjusting seat post with two bolts, not just a single clamp bolt with the mount rotation being limited by a ratchet, helps a lot to find the best spot. The best spot might be between ratchet points. If you raise the saddle nose slowly you should feel the pressure on your underside moving. The pressure should be on your sitbones and not of significant magnitude in front ot them, and you should not be using your legs to hold yourself in place. You should be sitting on your saddle with stability with your back straight up and with your pelvis and back rotated forward to reach the hoods and preferably the drops.
For me this last paragraph is really important in fitting myself. It works for Mrs. Road Fan as well and for a tri-winning neighbor lady whom I helped once. It also mirrors a lot of what Carbonfiberboy recommends, due to his long experience and his research.
#37
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By "negative 2 degrees" do you mean that the nose is up or down?
In the current saddle position, are you tending to slide forward as you pedal? If so I would gradually move the saddle nose up. This is where a micro-adjusting seat post with two bolts, not just a single clamp bolt with the mount rotation being limited by a ratchet, helps a lot to find the best spot.
In the current saddle position, are you tending to slide forward as you pedal? If so I would gradually move the saddle nose up. This is where a micro-adjusting seat post with two bolts, not just a single clamp bolt with the mount rotation being limited by a ratchet, helps a lot to find the best spot.
Thanks
Glenn
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I would suggest you try to raise the nose of the saddle in small increments, maybe 1 mm measured against the seat tube or ½ or ¼ degree measured with a decent level. As you raise it your oozing forward will slow down and eventually you'll perch on the saddle with some stability. At that position the nose might be pointing somewhat upward, but that's ok, your body is not on the nose of the saddle, it's on the wide part. But while you sit on the wide part there might be pressure in front of the sitbones, on the perineum. This could cause abrasion if your saddle is too high, and numbness if the pressure is on the perineum If you have these you need to gradually lower the nose down, noticing how the pressure points change.
In effective saddle height, this all tends to reduce actual saddle height as measured to the sit-bone contact point, as well as how it all feels, your term, "effective saddle height."
In effective saddle height, this all tends to reduce actual saddle height as measured to the sit-bone contact point, as well as how it all feels, your term, "effective saddle height."
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I would suggest you try to raise the nose of the saddle in small increments, maybe 1 mm measured against the seat tube or ½ or ¼ degree measured with a decent level. As you raise it your oozing forward will slow down and eventually you'll perch on the saddle with some stability. At that position the nose might be pointing somewhat upward, but that's ok, your body is not on the nose of the saddle, it's on the wide part. But while you sit on the wide part there might be pressure in front of the sitbones, on the perineum. This could cause abrasion if your saddle is too high, and numbness if the pressure is on the perineum If you have these you need to gradually lower the nose down, noticing how the pressure points change.
In effective saddle height, this all tends to reduce actual saddle height as measured to the sit-bone contact point, as well as how it all feels, your term, "effective saddle height."
In effective saddle height, this all tends to reduce actual saddle height as measured to the sit-bone contact point, as well as how it all feels, your term, "effective saddle height."
I think that's a good plan.
Thank you.
Glenn
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