P1s are garbage. Get a crank-based meter. That has long been and continues to be the best location for measuring power accurately.

Do you have the P1s? Why would you say they are garbage??

I have P1 pedals and they are great!

Please elaborate on your expert knowledge of the P1S, maybe I'm missing something

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Yellowfin Endurance Coaching and Bike Fits
USAT Level 1, USAC Level 3

This. I have a pair of the P1s (both sides). They are excellent. They have been flawless. Why would they be garbage?

That said I wouldn't want a single-sided power meter. I have found I have a power imbalance that is much more prominent on flat terrain and much less so in hilly terrain. I would much prefer to have double-sided power.

Well, I did, until today when I returned them because I realized right away how terrible they were. They aren't accurate and they can't be verified to be accurate with a static torque test or any other manual calibration. My observation was that the stochastics of the measurement were totally wrong -- the single second recording data is all over the charts compared to any other meter I've used. They really only do a decent job net-net because there is an algorithm that does a pretty good job of accounting for the shoddy nature of measurement on average and smoothed longitudinally. You can see this in the charted accuracy data from DC Rainmaker, but I wanted to verify it myself.

They may work for you if you are interested in a power toy, but they aren't the proper tool for a serious cyclist. If I'm spending that kind of money I'd prefer to not have to slap a 30 second moving average on my data just to bring it into line with reality. But I'm a bit of a power purist, so to each his own.

Not sure what you're talking about with DCR. Here's his opinion of the accuracy,"

Sorry I must not as serious a cyclist as yourself, I just like toys

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Yellowfin Endurance Coaching and Bike Fits
USAT Level 1, USAC Level 3

Hey don't get all bent out of shape just because you guys have shitty power meters. Maybe you should also pick up that one that measures power from a heart rate strap while you're at it.

Ok, so what I am getting from your strong feelings towards the P1S pedals, is that 1. You should not have a one sided PM. 2. You should not have a pedal based PM. 3. Crank based is where its at.

Mind me asking which crank based PM you have and why you like it so much better? Thanks

You nailed it.

I have 5 Quarqs, an SRM, and the Kickr 2, which isn't crank based but I tolerate it. In general the Quarq's have been best for me and the customer service experience at Quarq is superior to the others. So that is the meter I would recommend. You can get a like new used one for like $650 in the classifieds so around the price of the 50% power meter pedal system, which manages to deprive you of the only benefit pedal based meters have over crank based meters, which is true left right balance. So no I don't understand why you would buy the one pedal thing.

 Well I appreciate your feedback! I am going to think twice about the pedals! I am a powertap fan, and really want to stick with them. Any word on that?

Yeah Powertaps are rock solid for the road. They are only $300 too so a really good option -- for about $800 you can have it built into a good rim. So yeah I think it's a good option why aren't you sticking with that?

Before you believe somebody so biased, read the power meter roundup from DC Rainmaker and notice how he said the Powertap pedals are the ones he would buy if he had to only have one meter.

https://www.dcrainmaker.com/...ide2016-edition.html

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Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com

I have p1's and while I think they are great this far, I can appreciate the detailed opinion on why you don't like them. I think this is one of the first really significant dislikes for the p1's that I have seen.

I only have experience with P1s, but isn't instantaneous power always pretty rough, isn't that why almost everyone seems to use 3 second or 10 second power for workouts? You're tellling me some people find unsmoothed power data useful?

I should have been a little clearer. I display 10 second and 30 second averages on my Garmin, which were themselves far more jumpy than with any other meter I've owned as a byproduct of the excessively stochastic single second data. By extension I also believe that normalized power is inaccurate -- because of how NP is calculated, it is higher than it should be, which makes for an artificially buoyant IF, VI, TSS/ATL/CTL, and all other metrics derivative of NP (or Skiba's xPower/Strava's weighted average). So while average is important, many other metrics that matters in performance modeling applications for power data are imperiled with the P1s.

I raced with the P1s on Saturday on a pancake flat course with next to no coasting (averaged 102 rpms). NP was 5 watts higher than AP and I have never seen even close to that before on a flat course (VI is always <1.01). Hell my NP was only 6 watts higher than my AP in St. Croix, one of the hilliest most technical courses on the circuit.

I could have done a full side by side of the P1s compared to other crank based meters but I didn't need to -- I have significant experience with power data and I know when something is amiss.

DCR is good for a lot of things but recommending products to the few hundred people who banter back and forth about this minutia on the Wattage Forum/ST is not his prerogative. So yeah I disagree with him on his recommendation if you are a true power user. SEE WUT I DID THERE?

Yeah see my comments above. DCR increasingly gears his recommendations towards the fat middle of this mass market -- not towards serious power users.

By the way, I'm not the only one who thinks this about the P1s -- the forum overlord and engineering supernerd in your signature made a similar assessment of the things (here and here) along with one of Powertap's sponsored athletes who also seems to distrust the veracity of the data.

All I'm saying here is if that you want a high quality power meter you should go crank, chainring, or hub based.

I display 3s and I have never seen it THAT jump or jumpier than Quarqs or PT.

I also have a gazillion of roller WOs and they look pretty even during and afterward.

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

Whilst you may not want to hear what PV is saying he is does say it well and makes some very valid points. I had the P1s and ended up getting rid as they were unreliable.

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https://ascentsportscoaching.com

I get what he is saying but it has never been an issue for me at least: when I am aiming XYZ watts I am pretty much right on the number as I ride. perhaps u guys can post a file showing the jumpiness?!?!

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

I've owned several power meters in my day. Quarq, SRM, Ergomo (yes, I did and liked it), Polar, ibike, Power2max and Powertap P1's. I will agree a crank based PM works best for me. But, I find the P1's are good and read really close to others. Making sure you have their cleats and good batteries are necessary. I do feel like I am somewhat of a serious power meter user and have used it for quite some time, for whatever that's worth.

So...to summarize.

You're extremely deep in power numbers and data, but you actually haven't posted any real numbers. Rather, just a gut feel. Meanwhile, those who post tons of data aren't apparently the target audience for people that want data here. Or did I miss something?

There are certainly downsides to the P1's, but quite frankly accuracy isn't one I've yet heard from anyone. Downsides can be production/manuf quality issues on what appears to be older units, battery caps prone to stripping (also older, not really an issue now), and people using the wrong battery types.

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My tiny little slice of the internets: dcrainmaker.com

;)

"in god we trust everyone else bring data"

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

You won me over with "forum overlord." I literally laughed out loud. I like the cut of your jib. :)

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Zen and the Art of Triathlon. Strava Workout Log
Interviews with Chris McCormack, Helle Frederikson, Angela Naeth, and many more.
http://www.zentriathlon.com

I have the L/R set of P1s and have enjoyed them. I have had a couple rides where the batteries died and was able to stop at a gas station to replace them so I could continue to have power for the remainder of the ride. Only concern with one sided power is that the numbers may have higher variations on higher intensity rides and efforts. I tend to be 47% L / 53% R on with my power, but have seen the ratio move farther apart on higher efforts. I don't think this is a make or break issue, but is something to consider. The ease of removing this power meter from bike to bike is the main reason I swapped from hub based power to pedals. Plus I can use it with my 10 speed Tri bike (which I race with older HED H3s) and my 11 speed road bike that uses updated Mavic wheels. Give DCRainmaker's blog a glance and see what he has to say about power meter options and see what jumps at you as a good choice.

Ray--first, there are a lot of things you are good at but indicting shitty power meters for inaccuracy is not one of them. It took you, what, nearly three years to add a note to the accuracy section of your Kickr review stating that some users have experienced issues. Seriously? That integrated power meter is so broadly and materially abysmal that all of the trainer apps have had to develop this 'PowerMatch' functionality so users could use another power meter, an external power meter, to fix the completely unreliable one from Wahoo that is included with their $1k product. And don't even get me started on your swooning over Stages, a power toy if there ever was one.

Second, I think you unfairly characterize my assessment as "gut feel". I know how I ride and in my half dozen or so rides with the P1s (and the one race on Sunday) showed me variability in the high level metrics that was exaggerated compared to my other units. If my DZero units had arrived in time I would have run a more robust side by side analysis, but I was convinced enough from the data I saw to date that I just went ahead and got my $1200 back. I like data but I don't do this for the consumerist masses as a profession like you so I went ahead and shipped the pedals back before running several full on multiple unit correlation tests, which as you know are not entirely instructive anyways. It's entirely plausible I got a bad pair, which can happen with any unit. But when it happens with an SRM I know how to verify what I'm seeing at home using basic tenets of physics (and a high quality weight of known mass).

Third, I don't know why you are saying that this is the first you've heard of accuracy issues unless you don't read the comments on your reviews, which of course you do. The comment section of your P1 review is like a de facto support group for customers who are having issues with these pedals.

Finally, your assessment of consumer-grade power meters is that they are prone to issues in general and unreliable as a rule, but individually you don't do a very good job stating which ones suck. Well, I'm telling you. The Wahoo Kickr OG sucks. The P1 pedals and especially the Garmin vectors suck. Stages sucks. Those new Brim Brothers jawns will suck. The one on the handlebars...I won't even go there. Why can't we just accept and agree that there are better places to measure strain than others? And there are better places than at the pedal.

There has been some hinting that P1's may not be as accurate in the upper steady output ranges (say 350-400 watts). Have you done any testing at that range to confirm they are accurate vs. say PT hub or SRM?

This was hinted at by a couple pro triathletes this spring as they were setting all time FTP type records on PT pedals. Where of course their FTP is mid-upper 300's.

Thanks.

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24 Hour World TT Champs-American record holder
Fat Bike Worlds - Race Director
Insta: chris.s.apex

So again, to recap, you've got no data.

Check.

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My tiny little slice of the internets: dcrainmaker.com

A lot of what I've seen there comes from I believe the BikeRadar review where they made some comments there, but it seemed to be related to really old firmware, as they later hinted at in some text (but not in the video review). Unrelated to that, there was a bug someone found late last year (Dec?) that was fixed I think in Jan/Feb around certain types of inclines where it wasn't properly resetting/zero'ing. It was a weird outlier that I think only 1-2 people saw in comments, but PT subsequently fixed via firmware update. I didn't see it during my rides in the Alps last year, though from talking to PT it has a very constrained set of requirements to get you into seeing it.

You'll see the P1's used in many of my power meter reviews, along with other power meters (usually 3-4). Including plenty of 350-400w chunks of data. Each of those reviews includes all of the data that folks can analyze/download/etc...and nobody has found anything amiss there.

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My tiny little slice of the internets: dcrainmaker.com

Excellent thanks.

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24 Hour World TT Champs-American record holder
Fat Bike Worlds - Race Director
Insta: chris.s.apex

Pubes how about doing a ride and tracking your quarq and p1s at the same time and post the results here?

Yeah...well Ray has left me no choice but to do just that. Challenge accepted.

They won't even exist. You need to keep up with current events.

Touche. I'm a couple days behind on my RSS feed so didn't see the news about Brim Brothers from yesterday.

Public service announcement to everyone....stop crowd funding stupid shit! Especially power toys like LIMITS, Brim Brothers, et al.

Let companies like Garmin and Shimano squander their own capital producing bad meters. Don't let them use your own to fail in this capacity.

he got u there tho...

Kickr is just not accurate and they even admitted on your kickr2 review.

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The entire event (IM) is like "death by 1000 cuts" and the best race is minimizing all those cuts and losing less blood than the other guy. - Dev

Actually, that's not what they said. They talked about how with the original KICKR it was more susceptible to failures, which in turn led to accuracy issues. Which is some people had no issues, and yet others had issues. By removing that element, they believe they're able to reduce the strain gauge failures which caused accuracy issues.

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My tiny little slice of the internets: dcrainmaker.com

This review ultimately lead me to get a crank based power meter (P2M). They did like the powertap hubs in this review too. Good luck finding a power meter.

Lots of talk of the P1s reading high at higher outputs (280+), has anyone posted data comparing the P1s to supposedly more reliable alternatives like SRM?

Also, what was the issue with battery choice on the P1s, are there certain batteries to avoid?

EDIT: Of course Ray posted lots of snippets of data, and his overall assessment, in his detailed P1 review. His bottom line assessment was, "I’m just not seeing anything in any of my files that even hints at power or cadence accuracy issues." Eyeballing the data snippets he posted, the P1s do seem to skew a little higher than the G3 hub at higher power output, though whether that's within the range of what would be expected given their position more proximate to the source of power, I'm not certain. https://www.dcrainmaker.com/...1-pedals-review.html

And as Ray wrote above, "You'll see the P1's used in many of my power meter reviews, along with other power meters (usually 3-4). Including plenty of 350-400w chunks of data. Each of those reviews includes all of the data that folks can analyze/download/etc...and nobody has found anything amiss there."

Any update, anxious to see...

I doubt anyone is suggesting Ray fraudulently massages the data he posts to make the P1s look good, and even if he improbably had that motivation it would have to be a pretty heroic effort. So I'm not even sure this requires any new data, someone could just take a careful look at some of the reams of data he's already shared. Ray's already made clear he doesn't see these issues, but that doesn't mean that someone else couldn't reevaluate the data to try to make an alternate case.