Power Meter Brand Reliability

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rijndael
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by rijndael

And FWIW, I have a lot of respect for Ray's approach and data. Some of the people helping him on the backside (data correlation) are very clueful.

Part of the problem is we're dealing with sample sizes of one, there are certainly going to be outliers.

KWalker
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by KWalker

P2M calibrates with a Cyclus 2 radial ergometer. Only brand that does it. If anything, your other units were off. PT hubs can lose accuracy over time....
Don't take me too seriously. The only person that doesn't hate Froome.
Gramz
Failed Custom Bike

rijndael
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by rijndael

The PT was 2 months old, the SRM was < 1 year old, and the Quarq was practically brand new.

I find it hard to believe that ALL 3 units were off, but the P2M was right. We were riding 20' intervals on a local high-school track. The gearing didn't change, the cadence was held pretty constant, and over the 20' interval - the P2M was dropping in reported wattage.

KWalker
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by KWalker

"pretty constant" isn't the the same as perfectly constant per TPs test or using an ergometer to calibrate. 20min seems like an awfully long time for external variations to influence readings in such a condition.

Its easy for me to believe that all 3 units could have been off. Simply look at how they are calibrated from the factory and the fact that they lack any sort of temperature compensation mechanism of any sort. As I said before, all of my SRMs read higher than my P2M, but they also changed calibration and had their own set of problems over time.

So did you contact P2M? If so, what did they say? What was their solution? Your case seems pretty weak.

Like TP I have performed the same tests with 10 powermeters with the same PT wheel. The P2M "reads low" compared to the SRMs, but those all read different from each other as well. The P2Ms were the only ones that were stable in all conditions and over time. I find it weird that you had this problem and aren't really providing any sort of details as to what the solution was. Sounds like you just don't like P2M and are trying to justify your current PM.

The key word of this thread is "reliability". You are speaking about accuracy. If the P2M read low all the time and had no other malfunctions then it was definitely reliable.
Don't take me too seriously. The only person that doesn't hate Froome.
Gramz
Failed Custom Bike

LionelB
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by LionelB

Talking about p2m reliability, is anyone here using the campy version of it ?

rijndael
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by rijndael

KWalker wrote:"pretty constant" isn't the the same as perfectly constant per TPs test or using an ergometer to calibrate.
It's impossible for a human to hold a cadence perfectly constant. The issue seemed to fix itself when we coasted for a bit, but during the 20' interval, we didn't do any coasting and the readings were down 6% from the start of the interval to the end.

KWalker wrote:So did you contact P2M?
I didn't. It wasn't my meter, but the owner did. It was sent back and replaced.

KWalker wrote:Your case seems pretty weak.
That's fine. Your perpetual pimping of P2M tells me you've already decided who's the the "best", I'm not here to convince you, I really couldn't care less what other folks use - pros included.

KWalker wrote:Sounds like you just don't like P2M and are trying to justify your current PM.
That's funny. I don't have any products that I "just don't like". They either work well, or they don't. I currently have an SRM, Red 22 and a PT. I'm not wed to any one product or vendor.

You're free to discount any bit of my experiences to and come to your own conclusions, whether they're informed or not. As I've said before, the P2M experience was a sample size of one.

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Tinea Pedis
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by Tinea Pedis

rijndael wrote:I didn't. It wasn't my meter, but the owner did. It was sent back and replaced.

You've based your whole debate (and results) off a faulty power meter....?

The internet, it never fails to deliver :lol:


For the record, mate of mine worked at the Australian Institute of Sport as one of the resident exercise physiologists. They had SRM's way out of calibration, brand new. My new 9000 SRM issues were documented pages back. It happens.As it seems to have with your mates Power2Max. Which it incredibly took over a page to establish.


LionelB wrote:Talking about p2m reliability, is anyone here using the campy version of it ?

Mate has one. He can only compare to Vectors - which it leaves for dead (in his experience).

rijndael
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by rijndael

Tinea Pedis wrote:You've based your whole debate (and results) off a faulty power meter....?
We haven't had a chance to retest the replacement.

The original point was that some brands are more reliable than others, and continually telling folks how great their PM company's CS is really shouldn't be a selling point, it's a tell that you've needed it. Some brands tend to be more problematic than others. Back in my original post where someone wanted me to name names, I didn't even include P2M because I haven't drawn any conclusions about them. I merely stated that if I got one, I'd want to make sure it wasn't one of the ones that read low.

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Tinea Pedis
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by Tinea Pedis

You included brands Stages in your original theory - a company that's a start up, whose first generation product has only just gone one year old and whose main issue was simply a fault seal. Which, in most cases, is remedied with new seals that arrive within a week. For me, that's rough to slate a company under that circumstance.

I see the point you're trying to make, but there's not a company on earth who doesn't have a product that will have issues and need customer support. Having too many issues, ala Quarq, not a great look and to a certain degree is telling. However judging off the amount of reported issues rather than customer service is still a false economy. As we (the internet) only hear of when it goes wrong, not all the times the stuff works as it should. So the real test is still how well the company stands behind and supports their product when failures occur.

rijndael
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by rijndael

Tinea Pedis wrote:Which, in most cases, is remedied with new seals that arrive within a week.
The folks I ride with are still having water issues, after replacement arms and many doors. They've started putting plastic shopping bags over the arms, with rubber bands, when they wash their bikes because they're afraid of having more issues.

Tinea Pedis wrote:Having too many issues, ala Quarq, not a great look and is telling.
Agreed, I'm on my 3rd one, I wish I wasn't. And I'm a bit nervous with my 2 year original warranty coming to an end in December.

Tinea Pedis wrote: However judging off the amount of reported issues rather than customer service is still a false economy. As we (the internet) only hear of when it goes wrong, not all the times the stuff works as it should. So the real test is still how well the company stands behind and supports their product when failures occur.
I don't disagree with any of this.

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Tinea Pedis
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by Tinea Pedis

rijndael, I can obviously only speak from what I've seen - and in those cases (and there has been a few) Stages replaced arms and the issues were solved. And that was only if the replacement covers didn't solve it. My "in most cases" was intentionally not a blanket statement. Just so we don't go down the same path as just happened with the P2M example ;)


And in fairness to Quarq, my two were replaced super quickly and their customer service was sensational. I moved on after the second to SRM, whose SRAM SRM I still have - and works great on my gf's bike. Only I wish SRM had even half of Quarq's customer service. That, to me, is the tell.

KWalker
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by KWalker

rijndael wrote:
KWalker wrote:"pretty constant" isn't the the same as perfectly constant per TPs test or using an ergometer to calibrate.
It's impossible for a human to hold a cadence perfectly constant. The issue seemed to fix itself when we coasted for a bit, but during the 20' interval, we didn't do any coasting and the readings were down 6% from the start of the interval to the end.

KWalker wrote:So did you contact P2M?
I didn't. It wasn't my meter, but the owner did. It was sent back and replaced.

KWalker wrote:Your case seems pretty weak.
That's fine. Your perpetual pimping of P2M tells me you've already decided who's the the "best", I'm not here to convince you, I really couldn't care less what other folks use - pros included.

KWalker wrote:Sounds like you just don't like P2M and are trying to justify your current PM.
That's funny. I don't have any products that I "just don't like". They either work well, or they don't. I currently have an SRM, Red 22 and a PT. I'm not wed to any one product or vendor.

You're free to discount any bit of my experiences to and come to your own conclusions, whether they're informed or not. As I've said before, the P2M experience was a sample size of one.


1. This is why using a trainer or ergometer makes it much easier. With a moderate load on an indoor trainer I can keep cadence within 2RPM for a test interval. Shouldn't be that hard.

2. What you're saying makes no sense unless something dramatic changed in barometric pressure or temperature. I thus would like you to publicly post said data because I think you're trolling and/or full of shit. 6% is a lot to vary and it would be weird that a PM would vary in anything but a linear manner as one environmental variable changed and the others stayed constant. If it isn't weather conditions or environmental conditions then again I do not understand how this can happen given that the PM samples at the same rate, angular velocity is supposedly constant, and no other single electronic or mechanical factor would alter readings. In the test myself and others have done on our own this has never occurred.

3. Was the owner a poster on Wattage that returned a DA9000 unit? If so the fault was found in the chainrings being out of spec with the bolt holes, not the electronics itself. I have the exact same unit and no issues. This is also the ONLY instance of that happening. Compare that to Quarq in which case almost every Quarq owner ever has sent at least 1 unit back if not more. Or every SRM owner ever having to recalibrate their PM and have the battery changed once per year.

4. Its not pimping, its stating basic facts and relating my own personal experience. FWIW I actually advised a good friend of mine to get a Stages the other day since it suited his price point and use case the best. I have no allegiance to any brand, but for most people think that P2M makes the best crank-based PM, but PowerTap hubs and Stages cranks are not bad options for a lot of people either given what they want to do. The fact remains that SRM has done nothing to update their PM electronics since going wireless years ago. That technology even has its flaws, which they've done nothing to address. They now have known issues with ANT+ data transmission. Quarq has gone through a lot of growing pains as well and still produces a lot of faulty units. So, in terms of crank-based powermeters there isn't a lot of serious competition especially as P2M comes in on the low side of the price scale. If my P2M started having issues and they had a failure rate equal to Quarq I would totally change my tune, but the fact of the matter is that they don't. Less than a dozen units have had any sort of bad problems. Considering my shop warrantied over two dozen Quarqs in the year I worked there I'd say that's pretty good.

5. So you don't actually own a P2M and thus have any experience using one? Between myself and TP we have had over 20 PMs and spent a lot of time on both. I think we can argue the point a bit better than someone that hasn't even owned a P2M.
Don't take me too seriously. The only person that doesn't hate Froome.
Gramz
Failed Custom Bike

rijndael
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by rijndael

Karsten - The data we gathered is just stuff we did as friends, it's not a scientific paper/study in some PDF that I feel is well suited for an online critique. It's good enough for me. And as I said, I'm not here to convince you.

To be frank, I'm not interested in going back and forth with you. I do follow the wattage list pretty closely and I simply find your debate methods irritating, I really don't want to be in the middle of it with you.

goodboyr
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by goodboyr

My group has 5 new model quarqs. Been running perfectly for two seasons now. No drift. No issues. As well there are 4 others with older model quarqs with no issues. So......does that balance out your stats?

KWalker
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by KWalker

Nope, because it doesn't change the fact that I've helped sell over 20 former Quarq users on P2M as well.

If you can't post any evidence to support your claim then don't make it. All it does is add negative information that isn't supported. If your test was valid and you have the data its not hard to post. I don't think what I had done previously is scientific necessarily. If I had not lost my external hard drive when I moved I would gladly post it. I understand your point that every brand has its issues at some point. I certainly can't deny that I was skeptical when there were a few bad 1st gen P2Ms with drift issues. Every company has some sort of growing pains. Stages and Quarq still seem to be having some, whereas P2M doesn't. SRM is what it is, same with Powertap.

The biggest takeaway for me is that when P2M, PowerTap, Stages, and Quarq had issues they tried to do something about it. Some solutions worked, some didn't. SRM's policy if they do anything is to replace it or blame it on something else.
Don't take me too seriously. The only person that doesn't hate Froome.
Gramz
Failed Custom Bike

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