you can change the rings on this crank at any time, don't need to take the crank off, don't need to recalibrate. just change the rings. you may also find at some point that you just want to change them for the gearing. there are some things i didn't mention, because i had in my head "power meter" rather than "crankset". one thing i'm critical of is the power meter that fails as a component. a pedal-based power meter needs to be a really good pedal, for example, not just the host for a power meter.

this crank has the following options, some of which will be qualifiers, some disqualifiers. ring options are 55-42, 54-42, 53-39, 52-36, 50-34. that's good. less good is that the crankarm lengths are 170mm, 172.5mm, 175mm. it would be nice of the crankarms came in shorter lengths. that's a disqualifier for some. i just sent a direct mail piece out 2 or so weeks ago about an infocrank closeout i know about, $550 for a $1,400 crankset power meter, with crank lengths down to 155mm. (those went about 15min after i sent out that emailer; i'm not selling them; but the seller told me that). some folks will need the shorter crankarms and infocrank and ROTOR are the best for that.

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Dan Empfield
aka Slowman

I agree, but I also think that the raison d'etre for a power meter is that its data will answer questions or solve riddles. When the question is tough or the riddle is obdurate it's a pain when you have one more question than before and it's "Is this thing working right?"

https://gplama.com/...ankset-power-meters/

Did you test for accuracy of the PM by a change? It’s gotten some pretty poor reviews to date.

And FSA soon too.
I can't think of a good reason for Triathletes to be interested in the D-A powermeter - doesn't have useful lengths, at this point it's not accurate, only advantage is that it matches the rest of the groupset.

I'm happy to answer questions about the review. But you gotta read the review first. Did you do that?

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Dan Empfield
aka Slowman

Well, at well under half the price you can have Favero Assioma pedals and still use the crank of your choice. So then the only use case is if you are, say, a Speedplay die hard and also a Dura Ace die hard. A pretty small use case. But it sure is pretty.

On the other hand, for all the hue and cry about how inaccurate this PM is, one-sided power meters have potentially much greater accuracy issues and there doesn't seem to be much of a hue and cry about those. We have a Stages that came with a second hand bike we bought, it read 10-20% off for both my wife and myself, the battery is now removed and it's relegated to use as a dumb crank on a trainer bike.

The path was known, but there's a difference between knowing the path and walking the path.

I did, and you glided over the known inaccuracies of the Shimano PM.

In the instant case, you also appended the label of “influencer” to both bloggers right before you mentioned the issue of inaccuracy that these “influencers” noticed, never mind that the publishing of your own review is an act of influencing. I don’t know if it was intended to disparage and parry, but it came across that way, because you never addressed the substance of the well-known issue.

Had this review been published an year ago, it would have made for a fine review. But times have changed, and to have published this without a substantiative discussion of the accuracy issue makes the review seem a bit late and irrelevant.

PS. I should add that i generally hold a dim view of DCR (one of his boasts from a few tears back I found quite distasteful) and don’t often read Lama, but the latter’s critique of the Shimano PM (which i did read) at least appears valid and worthy of addressing, especially as similar issues were noticed on another PM based off of the same crank design.

just prove I read the article Dan I believe you have a typo: "Claimed accuracy is +/- 2°" I think you mean Claimed accuracy is +/- 2%"

As for accuracy and precision it seems that is for another day or left to DC Rainmaker and GP Lama? they certainly are set up to do that sort of thing.

FWIW, you can get the 9100P in 165mm.

i don't think these are all the parameters that frame this discussion. as for me, i'm a speedplay guy, a confirmed speedplay guy, on the road, and i'm not really interested in changing from speedplay until other pedal makers recognize and adopt speedplay's features. if you look at our overview of pedals among the top finishers in kona, it's also obvious that speedplay shines brightest among those who know and appreciate the features in a pedal. the features in this pedal makes this an untrivial component to the discussion.

as for shimano's cranks, this is the dominant crank in the marketplace. not just shimano, but stages, the questionable-futured pioneer, giant, and others place their PMs in this crank and in some cases only in this crank. so, one area i'm investigating is the paradox of PMing this crank: it's the world's premier crank platform, but it also, apparently, is uniquely ill-suited to hosting a PM. until someone figures this crank out. i write this not because of what i've discovered, but just based on what i'm reading from others who've put a lot more work into this than i have.

beyond this, i think you're right, a pedal-based PM sidesteps the difficulty in getting a PM to work on a shimano crank, and a pedal-based PM is modular. but as i wrote in the review - and i'd be shocked if even half the people commenting to this review even read it - the larger question going forward is whether PMs will eventually just be ubiquitous on bikes sold above a certain price, with that price creeping down, down, down. you have both bike brands (specialized and giant) near the ability to offer their own PMs OE, and you have component makers (SRAM, Shimano, FSA) working on it. if you get an FSA PM stocked OE on a $3,500 tri bike, or a Quarq on a SRAM Force AXS 1x gravel bike selling for under $4,000, that's going to apply pressure to the market.

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Dan Empfield
aka Slowman

thanks. my mistake. it could be that shimano just hasn't updated it's website or that i'm reading it wrong. this is what i see there as of this morning:

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Dan Empfield
aka Slowman

Perhaps they discontinued it for 2020, but they had availability in both warehouses last time I ordered one (early January).

Nothing shorter than 165 was ever available, to my knowledge.

My N=1 experience is that the accuracy complaints of these powermeters is grossly exaggerated. All 3 of mine have matched my SRM & Kickr within less than a percent.

i don't think that's fair. the PM also has a rarely-matched battery life, and it's a rechargable battery. it kind of reminds me of ROTOR's PM (the 2INpower), with a USB magnetic port charger applied to the crank. i think the shimano's battery life is a big deal. there's a number of habits i've had to acquire as an old boomer who came to adulthood several generations ago, one of which is to be vigilant about charging stuff at appropriate intervals. shifters, head unit, varia, any other lights i'm using, PM. tyre whiz. heat shield. photon torpedos. you forget one of these and you're about to commence your ride and... doh! i appreciate the battery life.

but i'm not here to champion this PM. were i to buy a new PM today this probably wouldn't be it. but, imagine if this PM comes out next year as an ultegra PM, and it's about a $600 upgrade from an ultegra crank. imagine shimano solves the unique issues that make its crank PM-unhappy. then what? yes, we have a crank length issue, even if this crank is made down to 165mm, but those who need cranks shorter than that are edge-case, and probably not part of shimano's mission.

we may be - what - a year away from a world where you can choose from a force axs PM, an ultegra PM, an FSA PM, as well as from giant and specialized, and these would all be candidates for OE. we may also be a short time away from a speedplay PM. did wahoo have any discussions with brim bros before they bought speedplay? i have no inside info from shimano or wahoo, but i'm not a compleat idiot. (there's a 60s reference there.)

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Dan Empfield
aka Slowman

i'm interested in hearing from GPLama and i hope he posts to this thread. i'm a fan of his, an eager youtuber of his. (and i sure wish he would do all that stuff for us!) now, perhaps i misremember, but because you brought him up, i *think* what the takeaway is from not just his shimano review, but his other video reviews of PMs attached to this crank, is that it's a *crank* problem. that doesn't diminish the problem. just, sauce for the goose. is giant's PM more, equally, or less inaccurate than shimano's PM? so, maybe this is fair and maybe it's not, but i parse between the PM proper, and the crankset. in any case, i believe i referenced both GPLama and DC Rainmaker in my review, did i not? and shane may hoist me by my own petard right in this thread.

i don't believe i glided over the inaccuracies. i specifically stated - and quoted - over multiple paragraphs, what those who are smarter than i am have to say about this crank's accuracy. i also state why i'm not saying more about this: because i don't have anything of substance *yet* to add. i thought i was pretty clear that what i wrote is simply what i know today; and that this is the first of a number of pieces i'll write that speak to this crank's utility. a *lot* of people are dead sure - they know for sure - exactly how accurate or not this crank is, and many or most of these have never even seen one, let alone installed and used one. i'd like the chance to do my own investigation rather than simply adopting others' opinions.

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Dan Empfield
aka Slowman

What is that 'upgrade' pathway? What would that look like to you in the bike-shop-of-the-near-future? Or do you mean a factory option? I wasn't clear from the front page article how this Dura Ace one is even getting on bikes. You mentioned OE, but I didn't understand if they were coming out of the factory on bikes right now. It's not like a consumer can buy direct from Shimano either. I couldn't imagine a bike shop wanting to stock these when there's so much variance in lengths and chainrings. At least they settled on a single bcd.

It seems the current pathway is buying the thing for the price you mentioned and selling your old one. The 'sold' listings on Ebay for a used 9100 crank are around $250 USD. That's a huge hit to take for an 'upgrade' with some of the other options out there. Unless it's about a $600 upgrade when ordering from the LBS, I don't see a path forward for this.

One thing is certain, these sure look nicer than some of the clunky spider based add-on power meters.

Thanks for being so active in the conversation/replies.

Hi Dan,

Thanks for taking the time to chime in (and I mean that sincerely).

I think you are right that the error lies with the design of the crank. Specifically I think it was the confluence of a) design of the crank (specifically 9100 and 8000 series) and b) assumptions re: sampling, which were valid for the previous generation stuff but not for the 9100/8000 series.

I think my tone in my original post was overly harsh, and I apologize for that. I think in my mind I would have preferred something that came out all at once (so that it includes the current post, plus your own investigation, which hopefully addresses the issue raised by others). But, as the saying goes, easy to critique but hard to make something. So I'll zip it and wait for the next installment of the update.

right now i'd say there are very few bikes that come with this as a factory original equipment option. one of my theses in my front page article is that the real price of a PM is the PM + whatever (if anything) the PM replaces. for example, an assioma replaces the pedal. you don't have to buy a pedal. the real price of an assioma is the price of the assioma minus the price of the pedal you'd otherwise have to buy. same with this shimano PM.

what i think - and i believe ray feels likewise, and i think others do as well - is that shimano, giant, FSA, specialized, SRAM/quarq, all these brands getting heavily into their *own* PMs creates the likelihood of a world in the near future where PMs come on bikes standard. the upcharge (in my parlance) between a pair of bikes with and without a PM is the difference between an ultegra crank, and an ultegra crank with a shimano PM (if that ultegra PM eventually gets made). at some point, on some bikes, that becomes a compelling option.

so, my wager is that PMs are going to come on bikes OE and that's why this dura ace crank here is important. right now, not many come OE. in 5 years? it's my guess you'll be buying most of your cranks OE unless you choose pedal-based PMs. a part of that calculus will depend on how bikes are assembled. right now, ABG assembles all its litespeeds, QRs, ocoees, in tennessee, at the point of sale. this gives QR a tremendous strategic advantage. this is where PMs bought on newly purchased bikes will manifest first. if you buy a speed concept you'll likely buy it as a project one purchase. same paradigm. one unknown is how many bike makers will adopt final bike assembly in the US and in europe.

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Dan Empfield
aka Slowman

no apology necessary, my friend. for those who didn't read it, here is exactly what i wrote on the front page:

Claimed accuracy is +/- 2°, and Shimano is confident that its units are both accurate, and are consistent from one of its units to another. Mind, the influencer class is not yet convinced. DC Rainmaker recently wrote that this power meter has been, “widely regarded as the least accurate mainstream power meter in 2020.” Is that fair? Meaning, are arbiters united in this view? And, is the power meter inaccurate, or are the opinionators inaccurate? I don’t know. Yet.

Ray answers a particular question for every power meter in his (excellent, and) most recent Power Meters Buyer’s Guide, “Would I buy it?” When Ray doesn’t much like a power meter one way he often answers this question is, “It’s tough.” He’s less equivocal about the Shimano. Would Ray buy it? “I can’t see a scenario where I would.”

About the accuracy of this PM, I’m not confident I can speak with authority. (I'll be on more firm footing in future installments on this PM.) But it seems to me that any accuracy issues are minor, are limited to one side, and not to the PM specifically, rather to crank-based PM affixed to this crank platform, including but not limited to Giant’s PowerPro. (I would defer to Shane GPLama Miller's superior knowledge of this).

what either is or isn't fair is what i shaded on blue above. one thing i'm going to ask shimano is whether there have been firmware updates to this crank since it was first written about. i believe the first to notice this one-side discrepancy was ben delaney, but this was 2 years ago. if others more recently are noting less of an issue, maybe that explains the delta in opinions. but i don't know. the truest thing you can say about me is that i don't have anything of value to write about this crank's accuracy.

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Dan Empfield
aka Slowman

I agree battery life is a nice thing to have, but is a rechargeable battery, even if it lasts a long time on one charge, really all that better than a coin battery like quarq or p2m use? Last year I spent $15 bucks on coin batteries and keep them in my toolbag. I never have to worry about being battery-less ever again. And that way the internal battery doesn't suffer the same degradation we see on all rechargeable battery-fed devices. Given, the life of the power meter may not be longer than the life of the battery in this case so that would be a non-issue, but still...

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
Deals on Wheels - Results, schedule, videos, sponsors

i don't have any quarrel with what you write. my response was to cyclenutnz, who said the only thing good about this PM is that it's congruent with the groupset. i don't mind anyone not liking this PM, not buying it, and pointing out its faults. but when your zeal to dump a load on this product causes you to misrepresent it, then i think it's fair to point out the virtues that are omitted.

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Dan Empfield
aka Slowman

Thanks for that little tidbit regarding final assembly for ABG products being slightly more local to the final destination. It sounds kind of like buying a new car where you can add on stuff like remote start, trailer hitch receiver, etc. at the 'port' for quite a bit less money than you would at the dealer.

yup. very few people appreciate the logistical advantage ABG will enjoy in this industry. i'm going out there later this spring to do a feature, not on the products, but on the company.

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Dan Empfield
aka Slowman

It is actually available in 165 mm and in 167,5 mm. I have the 165’s.

Jeroen

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Owner at TRIPRO, The Netherlands

You know, there are people around here who would be reasonably qualified to help you with this, were you so inclined. But I'd understand if you weren't.

yes, i'm blessed with some very smart people in this community on whom i could rely. i will certainly avail myself of the wisdom of these folks - perhaps you among them if that makes sense for you - and on a number of topics certain folks here have gotten a recent reachout from me. i've decided we should spread our wings a little, editorially, so what you're talking about is timely. but for more than one reason i was not ready to tackle accuracy in this article. i felt that cost, basic features, and most of all installation, was enough for this article.

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Dan Empfield
aka Slowman

The last 4 cranksets I've sold were 2x160 (one an R7000), a 155 and a 145. For people all roughly average height for their gender, the 145s were for a road bike. Shimano are take off cranks for me, the only advantage is that they have some resale value, unlike certain placeholder brands. I use 162.5mm on my tri bike. Which is why my original comment is that I don't see a reason for triathletes to be interested - 170mm is a long crank when pushing the boundaries of closed hip angle.

One of those was a Rotor Aldhu with inspider power. That is a good system - heaps of modularity, rechargeable powermeter, goes down to 155, tension adjustment on NDS. Unproven as a powermeter at this point but it avoids the fundamental issues of a lot of other systems so that's a good start.


OE powermeters on cranks are just going to be a headache as it will be increasing the cost of a part that needs to be changed for fit purposes. Properly modular like Rotor would be OK. As big a fan as I am of powermeters (won't coach without one and have 8 myself) I don't see that OE powermeters are a worthwhile goal - it's just a curiosity for the majority of bike riders.

The problem for me coaching athletes with a DA PM is that we don't know how accurate it is. Shane makes a convincing case that there is a fundamental design issue that means the expensive 9100 isn't really any better than a cheap Stages style system.

One of my athletes (have been fitting him for years, now coaching too) has completely worthless training history. Last year he had a 4iiii on DA that doubled the numbers on one side, then swapped to another 4iiii that underreads. His new team have Shimano (and insist on Shimano Cranks) but I'm left still not knowing whether his race bike is accurate. Which is a real problem when putting a CV out to world tour teams. 400 FTP is good, but every increment above that helps in getting a job. And I have to change his FTP in WKO per bike change while he still has the 4iiii on the training bike.

It will never happen but an industry standard dynamic calibration process would go a long way. Then we might actually be able to know the value of any particular PM.


I had to look that up as my knowledge of the 60s is derived from the Monkees, Adam Wests Batman and Beatles documentaries.

if you were broke, investing in bulk in boxes of kraft macaroni when they went on sale for 25 cents per, then you had a used VW and you relied on how to keep your volkswagen alive, for the compleat idiot. and if you can find a good copy of that now, it does, literally, cost more than the 1964 bus with a blown engine that i and my buddies bought. and we used that book to rebuild the engine (pursuant to taking that bus on a 7,000 mile jaunt thru mexico and central america).

but actually the original reference was probably the compleat angler, which was a famous (at the time) but since largely forgotten then-bible of flyfishing from the 16th century.

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Dan Empfield
aka Slowman

I will never forget helping a friend rebuild his bus engine on a picnic table at Joshua Tree with a copy of that book open in front of us.

Might be a poll question here...

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

i think you're right, about the poll question. one infamous passage, and this from a 50 year old memory, so, i'll mung it up, but, "if the green light comes on, hop in the back seat with your girlfriend and right about the time you two're done, start the car back up and go, but if the red light comes on..."

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Dan Empfield
aka Slowman

I read the article and have a 4iii dual PM on DA 8000. The articles tells me my PM is not accurate. My question is against what? I mean the number is the number. so long as said number is repeatable then I should be fine. And its not like I am using these numbers to get a contract somewhere! However the difference to my wahoo numbers is significant when I run both at same time. Wahoo is approx. 15W lower at IM power of 225. That is significant. I suppose just need to know what number is what for each PM and train accordingly.

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@rhyspencer

i agree with your entire post. as long as the number is repeatable, what's the difference of it's off a bit? but we also rely on other sources for our power number and it would be convenient of our smart trainers and our power meters were congruent.

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Dan Empfield
aka Slowman

Yes. 4iiii on road bike. Wahoo indoors. Suppose could use 4iiii as sole source but Bluetooth connections to ITV and cadence built in Wahoo I just go with trainer. It’s get complicated come summer and I start riding my P2s on my Tri bike but come then I suppose I wont be on my Wahoo🤦‍♂️

Really first world problems. It’s just a lot of toys!

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@rhyspencer

There are lots of uses for power data, some of which don't require much accuracy or precision, some of which do.

Training FTP is one of the least demanding things you can do with a power meter -- that's why riders have been able to train effectively with just a wristwatch and a regular training route, or with a HRM, for decades. Some people will only care about their FTP, and they use their power data pretty much like a wristwatch and just try to improve their time; or they use it just like a HRM, and they just ride in their training zone. There's nothing wrong with that.

On the other hand, measuring drag is a highly-demanding use for a power meter, because drag varies nonlinearly with speed and power; that means in order to solve the nonlinear drag equation you need to know the *actual* amount of power. So, you can train FTP with a wristwatch or HRM, but you can't measure drag with just a wristwatch or a HRM. If you were trying to tease out small differences in drag between, say, two different helmets, or two different tires, you're going to need both high accuracy and high precision. Ironically, people used to try to measure drag with coast downs -- that's a case where the power is accurately and precisely known to be exactly zero.

As I said above, generally we buy power meters cuz we're hoping they'll help us answer questions or solve riddles. When the questions are easy or the riddles simple, you don't need much accuracy; when almost everything lines up, you use the data more for affirmation than information. It's when the questions are hard and the riddles are ball-breakers that you don't want to be asking "I wonder if my power meter is working right? I wonder which of these numbers can I trust?"

Way above my head mate! . Honestly i have power to keep me engaged. Thats it. I am far on the downside of performance at 49. 20lbs heavier & 10+yrs past my top racing. I just find power fun to look at climbing, pulling a race group in a bike race, staying low and aero and in control in an Ironman, or looking at after for what i knew was incredibly painful workouts. Its just a number. And a game. Played mostly outside!

That said, what helmet do u recommend? I still race a Giro TT from 2006!

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@rhyspencer

Hmmm. Sounds like you have exactly the right helmet for your needs.

Interesting. I'll answer this in dot points as I've wasted way too much time on this specific issue, only to be shitlisted by most of these companies using these cranksets to make power meters. There's a reason I'm no longer reviewing other products these companies make and it's not my end. My door is always open....

- I test a LOT of power meters. I have a well established protocol that has proven itself over and over again. It's not perfect, but it works really well.
- ~18 months ago I was getting 'incorrect' data from ALL Shimano based L/R power meters. All of them.
- I could not (and still can not) use any Shimano based dual L/R power meter as a baseline to compare other meters to (smart trainers & power pedals) because of this.
- Diving deeper and deeper into this rabbit hole, I found something interesting with the right side readings.
- The explanation from the manufacturers was varied. From "Yeah, about that....ummm" to "We have no idea". They all know, or if they don't, they simply don't test to the level required for human riding. (constant torque testing is commonly used, humans aren't constant torque machines).
- I reached out to Keith Wakeham who's name is on the patent for this very design of power meter. Thankfully Keith was in a position to explain in great detail what the issue was. His video is all everyone needs to know on this issue. Kick back with a coffee and soak this in. It's brilliant and explains why there's no simple fix for this issue. https://www.youtube.com/watch?v=Zwt4Bx_FGHU
- So that was the issue explained. Finally.
- I set about putting all my data together and an overview of the issue. I sent this to all the named manufacturers two weeks prior to publishing. Two weeks later, I hit publish.
- I've since had a more Shimano based L/R cranks sent my way.. I've tested them, given the company the results (same same), and moved on. I can't be bothered at this time making more "Well, we knew this was a problem. Here's the data showing the problem" videos.
- As above, I don't talk much to the companies who make these meters anymore. I'm not spinning yarns they want to hear, but that's entirely on them. Make a better product. Simple. The 4iiii on the FSA crank was brilliant. It'd be interesting to test a Stages L/R on an XTR crank. But...

Back on topic: Shimano FC-R9100-P.

- As above. It has issues due to the base crank design.
- It wasn't designed as a power meter. It was an afterthought. That's proving to be a problem.
- I have reviewed this specific meter. Shimano said I was using the wrong firmware. (I wasn't. It was 4.0.7, "Update to make output value more accurate"). I updated the firmware anyway to 4.1.7 and retested, same issue. Shimano went quiet on me.
- There's multiple reviewers saying the same thing in regard to the data. DCR. Ben Delaney (over on Bike Radar). Myself. There's no motive here other than to talk on what we see from the data. And the data indicates issues.
- Are these units good enough to train with? Sure. They'll give readings good enough for most people. They just need to be aware of the shortcomings... and that what they've been sold might not be what they get.
- Are these units good enough for me to compare other meters to? No.

Other discussion points:

- "Why bang on about the inaccuracy of these and not left only, surely left only is less accurate". Because left only cranks ARE accurate for what they measure. Of course they won't represent your true effort if you're left/right wonky.. BUT... the left side is reading accurately.

- "Why do the pro peloton use the FC-R9100-P?". They're paid to. They also don't test power meters against other sources. They're professional cyclists. Maybe they know what's coming from Shimano so only have to spend 1/2 the season on these existing meters?

Take outs:

- I have no beef with Shimano. I love my Shimano Di2. It's brilliant because it's proven to work.
- I love the Favero Assioma, Quarq DZero, hell, even the random InPeak POWER Crank (Shimano Left only) that all do what they say they do. They work.
- I highly suspect Shimano will (or should) move to a spider based power meter for the pending DuraAce refresh. If they do, it's case closed on this issue. Write it off, move on.
- Pioneer exited this game a few weeks back. They were 100% reliant on Shimano cranks. What did they know that we don't?... Hmmm....

Anyhow. That's my braindump on this one. I just want to see power meters that work in the application I use them for. This doesn't.

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Shane Miller - GPLama
YouTube | Web | Twitter | Instagram | Facebook | Strava

Shane: Thanks.

Do you remember when the Stages was first released? Ray asked me and Tom to help him set up test protocols and analyze the data. Part of Ray's remit was that we wouldn't look at the single-sided issue -- in retrospect, I think he was right: when I review academic papers we're told to review the paper that was written, not the paper that should have been written. Ray wanted us to help him review the product that Stages had made, not the product that Stages should've made. Anyway, what we found was that there were problems with the data from that first model. Stages denied there were any problems, said they had expensive calibration tools and that we didn't know how to evaluate power data. Then they tested and found out that we were right, delayed their release by six more weeks, and tried to release firmware updates to address our issues. The bottom line is that, in the end, consumers got a better product than if we hadn't done a careful analysis and identified their problems. *That was a good outcome.* I just wish they hadn't trashed us but you can't have everything.

That's what you've done. When Shimano gets around to improving their power meter, it'll be because you (and Ben Delaney, and Keith) raised a ruckus. That's pretty neat. I just wish they hadn't trashed you but you can't have everything.

Dan....an important aspect of all reviews these days is some form of declaration by the reviewer about the source of the unit and payment. DCR does it all the time and has a clear policy.
So questions would be:
Is this a unit supplied by shimano for you to test?
Is this a paid review in anyway?
I just think in this era any review should make it clear from the start whether it is truely independent etc.....
This is not an accusation, but just an important component of reviews in today's world.

very reasonable post. no problem. we state quite clearly what our policy is, and often in duplicate. our partners are always listed at the bottom of every page. we don't engage in "paid media." we often, also, state it in the article just to be clear. we list shimano as a partner, tho this brand is not in for the long haul with us, month in, month out. shimano absolutely does occasionally run a campaign with us thru the year, they wrote us checks last year, and they almost certainly will this year.

therefore, i think it's safe to assume that we will cash a shimano check this year, and you should filter what we write through your cynic's goggles. that's likely to be the case with a lot of our reviews this year, as it appears we are (for whatever reason) in favor with the manufacturers in 2020. as gplama explained above, they can be fickle.

if this PM proves to still generate errant numbers one side, there won't be any hiding that here.

yes, the unit was supplied by shimano. i don't intend to keep it when i'm done. and i never sell product that is provided for review. my policy is that i prefer to pay for product that i review, but [rant mode] i don't feel the need for the manufacturer to profit from this. brands usually don't in my experience have an industry price just for those of us who're buying a lot of products only for testing purposes. [/rant]

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Dan Empfield
aka Slowman

thanks for the information and the transparency. that's a very helpful overview, and it comports with what i've heard you say in your videos on crank-based PMs deployed on this crank platform.

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Dan Empfield
aka Slowman

It kills me that Pioneer is getting out of the business, though I admit I'm surprised they got into it. Love, love, love those cranks. If I didn't already own more than one, I'd pick up another one now. They're selling what remains all at a good discount.

You can't for this PM. They're one and the same. Stages, et al, had an excuse (if a weak one). Shimano has none.

right. what i meant is that all these power meter makers - pioneer, stages, shimano - seem to come up with a similar problem: a bad measurement on the right side only. what they all have in common is this problem on this crank. if the labors of these PM makers were pointed toward another crank design, then they'd have less difficulty one assumes. hence my comment (if badly written) that the engineers at shimano may have been doing everything right, in the design of the PM. that shimano couldn't even get it to work while building into the crank is further evidence that there's something maddeningly odd about this crank.

it's a damned curious problem. i'll be in my workshop in a little while comparing power numbers across a number of power measuring devices including this one. i think it's a little harsh to say that shimano's engineers have no "excuse". i suspect they're beating themselves up over this. there have been firmware upgrades since ben delaney first wrote about this problem 2 years go, and I've asked for detail on each. gplama was generous enough to trade some PMs with me yesterday on my simple question of: why didn't they simply log the variance from actual and assign an algorithm to normalize?

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Dan Empfield
aka Slowman

GPLama linked to a Youtube post by Keith Wakeham on his site. Wakeham is an engineer who's designed power meters before. I'm not an engineer, and I didn't fully follow his arguments, but I do recall him saying that the error can't be compensated for in software. It's just too complex, and it stems from the asymmetric design of the crank spider.

yeah. GPLama explained this to me in some PMs we exchanged in the last few days. and, i watched keith's video. very interesting.

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Dan Empfield
aka Slowman