Dual-Sided Power Meter Questions

Anyone use dual power meters? Just got a stages dual Crank and wondering what programs\ applications people are using to look into the power. The stages cycling app is quite basic and strava cannot see the data.

Anyone else find out they have a imbalance? My right leg is 6% stronger. Something else to work on now

  • Why? A difference is not necessarily a problem. Do you have any actual issues with pain, discomfort or other things that might be attributable to a potential power imbalance?

  • Be careful about assuming we can or need to produce 50/50 power in the first place. That is a construct of our minds to want “balance” but it may not be necessary or even ideal in all cases.

  • Add in the fact that power balance is likely to vary with things like power level, fatigue and maybe other factors. Not to mention the question of potential data accuracy that is worth consideration as well.

I just caution about looking to fix a problem that doesn’t exist… just because you learned some new data value.

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I do not have any discomfort been lucky in that regard, it was more of a tongue in cheek comment to be honest. I guess humans are not symmetrical even though we would all love things to be equal.

I record on my Garmin bike computer, both inside and outside, and Garmin Connect has a nice graph showing left/right power. For example here is part of TR Baird -3:

and same in Intervals:

and same in TrainingPeaks:

you can also use WKO5 and GoldenCheetah and …

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Cheers i will look into intervals.icu later. Been using wahoo but i have been tempted by the new garmins

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Noob question: What are the advantages of knowing my imbalances?
I‘m going to buy PM pedals and am not sure if I really need duals.

None. Except maybe if you’re way off like 60/40 it could indicate a problem. This is very rare.

This is not why you buy dual sided though. Dual is more accurate as single sided just doubles the single sided power number. This doubling is accurate only if you pedal 50/50.

In my instance and looking at my power for years, I’m all over the place with my pedaling anywhere from 42/58 - 55/45 (left/right crank). Many times this depends on the effort, duration and my fatigue. So if you’re just doubling a single sided I could be 42 (left crank) one day and 55(left crank) another.

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I have only just started using mine but i have a 45\55 inbalance. I never knew but now I am setting power records now as I had a left side only and must of been under reporting my power

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That’s not really the reason folk by dual sided, their purchase is more to do with accuracy. There’s lots of factors which affect your power balance in a ride and it’ll probably change throughout, One example, a one sided power meter might be recording quite low as youve got all your weight on the other side pedalling through corners but going through corners the other way it could read too high as your leaning on that side. Dual sided will balance that out giving you a more accurate/ continuous figure better to pace off.

BTW My PM is single sided though and whilst its still working I’ll remain single sided but if I ever replace it it’ll probably be with a dual system.

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Thanks for the information (to all three). :slight_smile: Never thought about it like that.

Another beginner question: Why is the good accuracy in power important? I’d guess the difference would be in the single digit percentage and that it smoothes out over multiple rides (like same imbalance or same changes in balance).

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If you have just a left side crank PM, for example, that’s fine if it’s you only source of “truth”. Many folks (as mentioned above) have some L/R imbalance which could be skewed by a single side PM. This makes comparisons more tricky between meters.

I bought Assioma pedals a few months back and found my L/R balance is anywhere from 51/49 to 55/45…either way my prior single side PM’s were running high from doubling my stronger leg! If I never wanted to “upgrade” I’d be riding blissfully with a slightly higher FTP :rofl::rofl::rofl:

My motivation for the pedals was to have consistent power readings between both my gravel and road bikes because I can easily swap the pedals.

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Ok, thank you for explaining. :smiley:

Yeah I’d like pedals too because of that reason, but don’t like the Assioma Shis because of the extra q-factor (I tried it out and was a bit uncomfortable). Too bad I use SPD everywhere. :see_no_evil:

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There’s probably other reasons for it but for me it’ll give me a more stable figure for me to pace off (in ride) rather than a single sided figure that either reading too high or too low depending which way I’m leaning /turning. If you are just reviewing post ride and not looking too closely at things the high and low readings tend to average out and the difference will probably be minimal. However on a circular course (always turning one way) they may not average out.

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SPD everywhere for me too!

Do you have room to move your cleats a bit to offset the extra q-factor? I was lucky that it didn’t affect my fit, but I’m sure that’s not the case for everyone.

Garmin Rally pedals are nice but their SPD’S are like 2x what I paid for Assioma Duo SHI :grimacing::grimacing::grimacing:

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Yes, but I use the same shoes on various bikes with different q-factors. I’d like to have power for my gravel and (sometimes) commuter bike. My road bike (with integrated PM) is 6-10mm narrower than the other bikes. That’s why I hesitate to go even narrower on the cleats. I could use pedal extenders on the road bike. Maybe the old assiomas + Hack or one-sided Garmin Rally are the easier way. :smiley:

Yeah, the Garmin Rally pedals look nice, but much too expensive. I could just buy two SRam Quarq PMs for less.

Thank you for the suggestions. :slight_smile:

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Yeah, I have the exact same experience. When I first got a dual-sided power meter, I paid close attention to pedal balance, and day to day it could vary from 50-50 to 45-55 to 53-47 or so. There seem to be about a million subtle things that factor in on any given day, so it’s all statistical noise as far as I’m concerned.

I could see it being useful for something like recovering from an injury where you’re favoring one side over another, or to spot a potential structural imbalance, but apart from that it seems more likely to cause confusion for new users than actually do anyone any good.

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[quote=“FergusYL, post:16, topic:83682”]
I could see it being useful for something like recovering from an injury where you’re favoring one side over another, or to spot a potential structural imbalance, [/quote]
Agreed @FergusYL - this is how I’m currently using my Stages SB20 for this purpose: Training plan after ACL reconstructive surgery - #5 by FergalK

Having had a significant injury resulting in a 70-30 imbalance (not surprising as I could barely walk and had obviously wasted muscles), I can see some value in dual sided power and bought some pedals to see my improvement over time. However, what this episode has really revealed to me is that however you do it, you want to measure total power. When you measure by doubling one side, you’ve got a massive source of error that you can’t see or do anything about. In my opinion, accurate total power is much more important than L-R balance or any pedalling metrics.

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This. When I got a dual-sided meter I found out I my typical split was 53/47 favoring my left leg even though I am right handed. It is interesting to know but it does not influence how I train or ride. Assuming your legs feel good and your pedal stroke is smooth enough carry on.

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@mcneese.chad

“I just caution about looking to fix a problem that doesn’t exist… just because you learned some new data value.”

… but what if I look like this?
onebiglegonesmallleg2

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