Dual sided power meters

Hi,
Has anyone used the data from a dual sided power meter and implemented a change in fit or technique that has resulted in a measurable difference?

I currently use a single sided stages which has been great, but am thinking of getting some Assiomas. I can feel a fair difference in the effort my legs put out(IMO) but I haven’t read anything that suggests you should try and alter it.
Kind regards

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I have always had “dual sided” power meters, or more accurately, power meters that provide power on both sides plus L/R balance (most recently: 2 x Quarq). The primary value I have found of having dual sided measurement is having L/R balance. Over winter months last year I did a lot of cadence work. Virtually all of my indoor rides are now very close to 50.0%/50.0% and outdoor rides vary only as much as 0.5% (e.g. 50.5/49.5). The interesting I found was that when it was slightly higher on one side, it was typically not my dominant leg that was higher.

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I have Pioneer dual side which I use it with Pioneer’s real time Force Vector measurements that basically gives me the real time of L/R wattage plus efficiency.

This helped me to improve my pedaling technic and minimize the negative force on the pedals from 6 towards 12.

To have Force vector measurement, you should either use Pioneer CA600 head unit or Wahoo.

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I have the Assioma Duo. Clipping out can be tough, but otherwise these are great pedals. I use my Garmin Fenix 5 Plus as my head unit, works great. Gives me L/R balance, torque effectiveness (I’m usually in the 75-78% range), pedal smoothness (21-22%), plus Assiomas now have cycling dynamics (analytics) - Power Phase (pedal stroke region where positive power is produced) and standing/sitting position.

Interesting and all, I guess…but at least at the moment, all pretty much meaningless, until coaches etc. come up with meaningful explanations for how to utilize the data to actually make us faster. And I’m not sure I’d hold my breath: data from pro cyclists show essentially no correlation between ‘pedal smoothness’ and being faster on the bike.

My wild-a$$ hypothesis is that you -might- be able to use the data as an indicator of fatigue?

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In my opinion, dual sided power meters are a pretty expensive way of quickly checking what your L/R balance is.

A power meter is useful for telling you things you don’t know/can’t measure but if you feel like you have one weaker leg then why not just go with that feeling and try to address the imbalance?

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I bought Assioma Duos just for the sole purpose of checking my legs imbalance. They aren’t all that expensive and my imbalance is 46%/54%. It has been ranging from 47%/53% but never higher than that. I knew that my left leg was weaker but never by how much. Now I can address that and get correct data from my left side powermeters too.

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So this is something of a hypothetical question:

When I had knee problems, my physical therapist had a small device which he used to measure the power in my left and right leg but also the power individually of the three big muscles in both of my legs.

There was a big difference between my left and right leg. And a really big difference between the three big muscles in my right leg so we targeted that in therapy.
After the complaints we re-tested my right leg and the balance between the three muscles was a lot better, unfortunately we didn’t test my left leg at that time as well.

Would that measured imbalance between the legs automatically transfer over on the bike or could you still get different results because you use your muscles in a different way on the bike when pedaling compared to when the muscles get tested isolated.

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Interesting! Any idea what the device was called?

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I’m not sure about the evidence base for altering pedaling technique or L/R balance as some kind of efficiency improvement. I’m sceptical that it would make a big difference to most riders.

In terms of training benefits - single-sided vs. dual power readings shouldn’t make a big difference to the accuracy of your training as long as you remain consistent. Single sided power is L-side x2 which may not be entirely accurate but is at least a consistent basis for the workload you are doing.

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Another plus have having dual sided pedals is that they are two separate power meters. This allows you some level of consistency checking - if suddenly you have a 40/60 L/R balance that is likely a problem with power meters. Having recently found that my kickr is way off (and variably off) having 2 separate pedals also measuring power makes it easier to identify what is wrong.

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I have a pioneer double sided and quarq combined and used to have a single sided. The purpose of a double sided or combined power meter to me is to not try to correct imbalances but rather to get accurate data especially for short intervals and sprints. While a single sided PM gets your semi accurate avg power that might be consistent, it doesn’t control for changes in bias as a function of cadence, fatigue, power, standing vs sitting etc. There is a range from 60%L/R that power falls into so single sided can’t possibly be accurate most of the time

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Thanks for all the really insightful responses, some very interesting responses and uses for it.
Ultimately it does look like a accuracy point of view.

My hope was going to be if it could be used during my bike fit adjusting cleats, and saddle to see if the were adjustments could result in better power balance, peak power, and ftp. (Obviously would be tiny amounts)

The second which was mentioned was the balance by correcting with pedalling drills. I had read a little bit about it with power gains from correcting the leg during the up phase pushing on the pedal. (Torque effectiveness or vectors)

Kind regards

This is an interesting topic. I currently have a single-side power meter and I am planning on switching to dual. My wife get my hand me down pedals so that she isn’t using virtual power any more.

One of the reasons I want dual sided is just so I get power data when I am doing the individual leg drills that are optional in some of the workouts.

Something I am wondering about is that if you did happen to have any sort of significant discrepancy in power between left and right legs, how would that impact using power match in ERG mode? Curious how TR handles power match with essentially two power meters on the bike.

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Sorry no, it was a small device with a bit of padding on it.
I would then have to push down or raise my leg and it would measure in newton meters I believe how much force was being used.

Depending on the position I was lying in the therapist could check the muscles individually.

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Dual sided power meters still report a single power number, while recording the two meters’ output. So an application such as TR (or any other ANT+/BT device/app looking at power) sees a single number, and does not need to know that it’s dealing with a single or double-sided meter.

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The accuracy issue of a single-sided meter lies in both the possible divergence from a 50/50 L/R balance (inducing a bias in the measurement), and the variability of this divergence (inducing avariation in the bias). The former is not so much of a problem as long as the same setup is used to set power thresholds and to measure against these thresholds (i.e. maybe your FTP will test 5% high, but then you will do all training on a 5% high measurement as well, canceling the bias), the latter is more of an issue because it introduces a non-cancelable bias between targets and measure.

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I’m skeptical of my Pioneer PM after watching this… https://www.youtube.com/watch?v=Zwt4Bx_FGHU

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Not only Pionerr but all Shimano based seems having issues. Would like to see results on SRM based cranks.

If you look into pioneer specs, there is +/-2% accuracy issues.

I have Tacx Neo plus Pioneer. I always use it with powermatch. But I am not sure how they calculated left and right. I will check next time.

Does your pioneer read close to the Neo?

When using dual sided PM, are you able to see real-time left right readings when using TR? I’m assuming that TR only displays total power, so you would have to connect to your garmin/wahoo at the same time.

Currently I also have a single-sided power meter. The only situation where I would want power from both legs added is when doing single leg drills or things close to that (e. g. when you focus on the technique in one leg, I tend to produce more power with that leg). Otherwise, I don’t think I have ever heard a lot of people training with it. Even metrics like pedal smoothness seem pretty useless at the moment.

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