Kai Winters

Hi all,
I'm thinking of getting a pair of power meter pedals and have decided on the Favero Assiamo's but I don't know whether to buy the Duo or Uno.
I like the idea of saving around $300 by buying the Uno's...$750/Duo, $460/Uno at Amazon...yes I know I can find them a bit cheaper and may but Amazon is easier to access.
What are your thoughts and suggestions?
Thank you,
K

asgelle

Search for posts by Robert Chung on the advantages and disadvantages of single and double sided power meters.

Barry2 

I chose single sided but couldn’t stand not knowing what the other leg was doing!
I quickly changed to dual.
For my second PM purchase, no question, straight to dual.

Barry

tempocyclist

I'd recommend dual sided, but in the grand scheme of things it likely matters very little.

Been on Favero Assioma Duos for years now, absolutely faultless performance. Great choice.

RChung

Almost everyone who thinks a single-sided power meter will work for them is right; almost everyone who thinks a single-sided power meter won't work for them is right.

IcySwan1 

How did you come to choose the Favero over Garmin or Speedplay?

Mike

rm -rf

What do you want to use the power meter for?

I don't do training plans, with planned power intervals. I don't care much about left-right imbalances. I'm not really tracking my season progress toward a goal, but I look at it occasionally, and I like to compare the current year progress vs previous years.

Instead, it's mostly for pacing. I know what kind of power numbers I can do for 20 seconds, 60 seconds, 4-5 minutes, 30 minutes. The 4-5 minutes are useful for some of the longer local hills. It's so useful, getting the immediate feedback from power, instead of heart rate or perceived exertion.

So I have a left side crank power meter. That gives me good enough data for pacing.

I had a 4iiii, which failed just after the 3 year warranty, and they wouldn't help me out at all. I went for 6 months during covid season without a meter, and really missed it. The left crank Stages I bought has been working great.

Ha, that's so true.

Kai Winters

Garmin and Speedplay cost more than I want to spend
I don't want to buy 4 pair of cleats if I go Speedplay
Favero seems to have the best reviews...bikeradar, etc.

IcySwan1 

Thanks, Kai. That makes sense.

Mike

ChamoisDavisJr

Jives with what Ray Maker says here as well;

https://www.dcrainmaker.com/2021/04/...rst-rides.html

“But one of the things I’m ever-so-slowly warming to over time and doing years of power meter accuracy testing, is that I’m less convinced that on the whole power meters are as consistently accurate as people think and hope they are. And that for most people, even with slight shifting leg imbalances, I don’t think it’s as critical an issue. ...

... I’m coming to the conclusion that there are so many ways for power data to be inaccurate on any given day from any given vendor, that the left-only doubling thing probably is a wash in the end.


In general, people put far too much trust in their power meters providing day to day accuracy. I’ve got great examples of super reputable units that just disagree on a random day for no reason: Quarq DZero vs Tacx NEO 2 or 2T spiking 3-5% different from any other day. Or a Favero Assioma pedal doing the same. Or a KICKR V5 doing the same. ... the industry is yet to the point where one can assume that a PR day of 5w higher or even 10w higher is a legit PR.

I’m not saying single-sided is the answer for everyone, but I am saying that the vast majority of people who say single-sided is useless, would probably be surprised to find out how quietly inaccurate their power meters and trainers are day to day over months/years”

I actually paid for a subscription to Ray’s analyzer tool to compare power from my stages and my Cycleops trainer. Conclusion? Close enough for fat, old and slow,

The truly fast guys on here can quibble over the minutiae. I’ll take “meh” because in reality I’m “meh”.

pennpaul

More of a curiosity, for people who went single sided to double sided, how different was the power between legs?

chaadster

That quote does not exist at the posted link. Did you incorrectly cite it, or is it a mashup, perhaps of DCR statements and/or your own ideas?

It does not meet the standard definition of a quote at this time, so clarification is appreciated.

AlgarveCycling

I'm only interested in 10s power and normalised power from my PM as an idea of what I'm doing and where I am - it doesn't need to be 100% accurate and I am not bothered about dual. I have a Stages 3 on my Trek crank arm but recently got a Wahoo Speedplay single-sided pedal set for my Wilier.

I'm happy with the Wahoo pedals, as usual, Speedplay construction is very good, solid.

RChung

Here's a comparison of a left-only vs. crank spider power meter. I don't actually remember which was on which axis, but the overall difference in mean power was 4%. The rider doesn't have a particularly "unbalanced" L/R split. (This is more evidence in support of the idea that single-sidedness per se isn't always the biggest issue in inaccuracy or imprecision).

RChung

Ray can write Rorschach ink blots and people Rashomon him all the time. He's saying that there are lots of failure modes for power meters. An example is that when Stages started selling a dual-sided PM, the Shimano RHS crank they installed the strain gauges on introduced new problems. It was dual-sided, but it wasn't really an improvement. In addition, in actual use, people often think they never need to check or even calibrate their power meters. So even if you buy an "accurate" power meter, there are variations across individual units either in installation or actual use that reduce accuracy. Here's the money plot from a study of actual power meters that were in actual use on riders' own bikes.

You can see that even SRMs and PowerTaps *in actual use* aren't perfect. This is what Ray was saying.

Finally, I don't know why people say if they're slow or new to using power they don't need an accurate and precise meter. That's like saying if you're new to woodworking you don't need an accurate tape measure. You need accuracy and precision whether you're novice or expert.

Barry2 

For me….. L / R ….. 55% / 45%
But I’m working on it.

Barry

AlgarveCycling

When I say I do not care about 100% accuracy I am, of course, talking about literal accuracy, not consistent accuracy for an individual unit - where I do want the unit to be true to itself.

A PM that's consistent with itself in terms of accuracy is all I need - not whether it is actually accurate in terms of watts I produce. PM's vary from pedal, to crank, brand algorithm, calibration etc. so I'm not concerned if a PM say's I am doing 400W and that is exactly what I am really doing.

What I want/ need is a figure on any given PM to work and build from.

I know what NP I want to hit for any given ride based upon using my PM and what I log and can compare efforts to. I know what 10s power I want to be holding. It is completely irrelevant if that is 100% accurate in real terms or not; all that matters is that I am working with a PM that is consistent with it's own individual 'accuracy' - i.e. when it tells me it is 200W one day, it is not 250W under the same load the next if calibrated. So long as I can build on that 200W with confidence, it matters not a jot if that is a real 200W or 190W.

I calibrate my PM before every ride. I find using a PM a very useful tool and I work with the numbers it gives me; I'm not too bothered if I'm really doing those watts or not, I just need to see numbers get better over time.

RChung

As you can see from Fig. 3, precision or consistency varies across individual units, too. Ray's comments about individual units applies: most people don't even know how imprecise and inconsistent their power meter data are.

That said, training is all that most riders use their power data for, and training is one of the least demanding things you can do with a power meter. That's not a pejorative comment, it's just what it is. There are things you can do with power data that *do* require accuracy and precision, but not many people do them: chief among those things is drag measurement. Exactly because I'm old, fat, and slow, I need to do drag measurement and optimization: I have no other choice; otherwise, I'd just be using power data to record my decline. I do all those crazy insane anal-retentive things that most riders think are unimportant so that on good days I'm just old and fat.

PeteHski

I have one bike with a single-sided Specialized/4iiii crank power meter, one bike with a SRAM Quarq spider power meter, a Kickr bike and an Elite Direto X. So 4 different sources of power measurement and inevitably there must be some variation between them. But whatever that variation may be I can't tell a damn difference between any of them in practical terms. They all work perfectly well for pacing efforts or following structured training plans and they seem to report power consistently enough that I can swap between them without any compensation. 250W feels like 250W on all of them. If there is a difference it's lost in the noise and of no practical consequence. The only direct comparison I've made was between my single-sided crank meter and the Direto X and the difference in power reported there was minimal.

So I would go single-sided and save the cash. I would only go dual-sided if there was some specific reason why I needed to compare my left and right power output.

PeteHski

I use mine for training and pacing. As you say neither is very demanding of the power meter and doesn't require dual-sided measurement.

Kai Winters

I've purchased a pair of the "Uno's"
Thanks for all the comments...much appreciated

RChung

Almost everyone who thinks a single-sided power meter will work for them is right; almost everyone who thinks a single-sided power meter won't work for them is right.

ChamoisDavisJr

First part of quote starts at the 5th sentence in the first paragraph under WRAP UP:

It’s just below this picture;



The second set of quotes are from further down in the comments as people ask for clarification. Rays replies are located at posts #28 and #30. His replies are offset in their own box to call them out.

Lol, I’m too dumb to have “my own ideas” on this subject. I defer the the guy who’s independently tested just about every PM on the market over the last decade.

He does very lengthy deep dives so I understand not reading the article at all, it certainly contains quite a lot of words.

chaadster

Ah, I did not read the comments. Thanks for clarifying.

Sy Reene

Can you elaborate on your Fig. 3 chart? Eg. if I look at the Stages results. Is that 1 individual unit tested 13 different times? Or is this result of having tested 13 individual different Stages PMs?