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Power2Max calibration questions
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I recently got a P2M NGeco and after a half dozen rides I'm finding it's reading lower than other power meters I've used. Two of those rides have been on my trainer (a Hammer) and the P2M was 15-16 W lower than the Hammer. Outdoors it also seems low but that's much more qualitative since its based on similar efforts on routes I know well and ride often.

As long as it's consistent then I guess I don't care that it's lower, though I am surprised by a 15 W difference given how well the NGeco tracks with other power meters via DC Rainmaker comparisons. So my questions are:

[1] Has anyone done the "Hill test" that P2M mentions for checking the calibration of their power meter? And if so, how'd it go?

[2] Anyone done a static torque test, and if so any tips?

[3] If you ride outside with one power meter and inside on a "smart" trainer, and they give pretty different results, how do you recommend accounting for the difference when keeping track of TSS in Training Peaks (switch your FTP back and forth?)?

I'm generally curious to see if anyone's had any similar experience with their NG or NGeco.


Also, to try and anticipate some questions/comments:
Why am I not using PowerMatch when on the trainer? Because I have my old tri bike set up with my same pad x/y parked on the Hammer for indoor training. I only put my current tri bike on the trainer to compare the Hammer to the P2M.

You're speculating based on only a couple rides? True, this could be much ado about nothing. I plan to race next Sunday on a course I've done many times and have lots of data to compare to. I also have a couple hill repeat workouts I've done many times (steady, steep climbs so wind, position, etc. shouldn't complicate things) that I hope to do with the P2M soon.

You switched from Stages to P2M and you expect the two to be the same, what are you an idiot? Perhaps, but I'll be damned if the Stages wasn't pretty much spot on with the Hammer and my PowerBeam before that, and power/effort indoors correlated really well with power/effort outdoors.
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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What does the P2M estimate your left right balance as? Anyway, to answer a part of your question - I have a P2M mtb power meter and tested it against my Powertap P1 pedals over 4 x 10 min efforts and found the two were within 1-2 watts of each other. I'd guess the P2M is more accurate that either your Hammer or Stages.
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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I had the same problem with my P2M Type S, It was reading very low. I did the hill test on multiple occasions and I sent the data to P2M and they agreed that on each occasion the meter was reading too low. I sent it back to them for calibration. It came back a little better but still off a bit. I will say their customer service was excellent they answered my querie the same day not like Garmin which took a week.

My newer P2M NG is spot on even after 1.5 years of use.
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Re: Power2Max calibration questions [rmt] [ In reply to ]
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The stock P2M NGeco doesn't do left/right balance
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Re: Power2Max calibration questions [rmt] [ In reply to ]
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rmt wrote:
What does the P2M estimate your left right balance as? Anyway, to answer a part of your question - I have a P2M mtb power meter and tested it against my Powertap P1 pedals over 4 x 10 min efforts and found the two were within 1-2 watts of each other. I'd guess the P2M is more accurate that either your Hammer or Stages.

I don't have any L/R data for the NGeco, and like jaretj mentioned the L/R balance is only estimated. I have a friend with some P1s I'll see if I can borrow. They'll be great for another comparison and a quick L/R balance check (though I know it can change day to day).

From their website it looks like P2M only has an Android app for checking and updating your firmware, is that right? I'm an iPhone user but I'll see about borrowing an Android to check and make sure I'm on the most recent firmware. I suspect I should be up to date since I just got the thing.
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Re: Power2Max calibration questions [titemple652] [ In reply to ]
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titemple652 wrote:
I had the same problem with my P2M Type S, It was reading very low. I did the hill test on multiple occasions and I sent the data to P2M and they agreed that on each occasion the meter was reading too low. I sent it back to them for calibration. It came back a little better but still off a bit. I will say their customer service was excellent they answered my querie the same day not like Garmin which took a week.

My newer P2M NG is spot on even after 1.5 years of use.

Good to hear about customer service. I'll give the hill test a try. Did you use the German website they link to, or do you know of an English version?
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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Use the german website and let Google Chrome translate it to english for you. For what its worth I tried the hill test with my type s and the calculated power averages from that website were within 1 watt of the average power that the type s reported during each climb (I did the climb 3 times as recommended).
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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I've very recently gotten myself a NGeco Road myself. I've only done a couple of rides so far and haven't done any proper attempts at checking the accuracy. I would expect it to be much more accurate than any of my easily available comparison tools (Elite Rampa trainer, friends single sided Vector 3 pedals, BBS analysis of ride, virtual power from KK Road Machine). I did a very quick and dirty comparison against the virtual power levels Zwift gives for my Road Machine which seemed to match pretty well - I'll be doing that again and more thoroughly in order to know how my efforts from now on compare with historical data from Zwift, but it's not really a test of the NGeco. I've also a BBS aero analysis for my last ride which gave aero values very close to what I had guessed - hardly accurate but nice that everything looks consistent so far.

I haven't come across Power2Max's suggestions regarding a hill test. I just had a look on their website and haven't spotted it. Can you point me in the right direction?
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Re: Power2Max calibration questions [Ai_1] [ In reply to ]
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Ai_1 wrote:
I haven't come across Power2Max's suggestions regarding a hill test. I just had a look on their website and haven't spotted it. Can you point me in the right direction?

Itā€™s on their FAQ page:
https://www.power2max.com/en/faqs/
Click on the ā€œSupportā€ tab and itā€™s the second question down.
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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Ah, looked in FAQ before but missed it. Found it this time. Thanks
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Re: Power2Max calibration questions [titemple652] [ In reply to ]
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titemple652 wrote:
I had the same problem with my P2M Type S, It was reading very low. I did the hill test on multiple occasions and I sent the data to P2M and they agreed that on each occasion the meter was reading too low. I sent it back to them for calibration. It came back a little better but still off a bit. I will say their customer service was excellent they answered my querie the same day not like Garmin which took a week.

Another ride on the Hammer this morning, this time with some above threshold intervals. The gap between the two was even bigger at higher power, though I guess thatā€™s to be expected. Overall the P2M is measuring about 8% lower. I need to find a day when I can get out to do some hill testing.

What was the turn around time when you sent your Type S back for calibration?
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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Quote:
From their website it looks like P2M only has an Android app for checking and updating your firmware, is that right? I'm an iPhone user but I'll see about borrowing an Android to check and make sure I'm on the most recent firmware. I suspect I should be up to date since I just got the thing.

There is an iOS app now but it has a bug that stops firmware updates. Power2max didn't give a date as to when it would be fixed. They said that the current firmware update would not affect my NGEco bought late in 2017 so Im sure that yours will be fine.
Last edited by: east31: Aug 21, 18 15:58
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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The Hammer is bullshitting you and so is every other smart trainer out there that's equipped with a power estimator. I had 3 P2M cranks and they've always been right on and uber reliable.

BTW my Kickr reads 30W higher... Should I believe that my FTP is 370W or trust my P2M?

What's your CdA?
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Re: Power2Max calibration questions [trailerhouse] [ In reply to ]
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All three of my P2M's read nearly the same with each other and my 2 PowerTaps.

They all read 20 to 30 watts lower than my Computrainer at 200 watts. I could be a Zwift hero if I used the power from my CT.
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Re: Power2Max calibration questions [jaretj] [ In reply to ]
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Yes, smart trainers tend to be pretty flattering on the power front. Combine that with fantasy bodyweights, and you can see why there are so many heroes on Zwift.

My outgoing P2M Classic has been extremely reliable & consistent. Battery life gets a massive thumbs-up.

29 years and counting
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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Hello
My name is Thierry, and Iā€™m new here and please in advance: sorry for my English.
I understand very well this subject because I have the same ā€˜ā€™problemā€™ā€™ (or simply: ascertainmentā€¦).
Maybe itā€™s not a true problem, but I would like to understand why the power of my P2M NG-Eco is 4 or 5% less than my Tacx Neo and that my Powertap P1ā€¦.
First of all, I think the measure is take only in the right leg with the P2M Eco and in the right and left legs with the Neo and the P1.
For my example: With the P1, I have always L-52%/R-48% or 51/49%. Never 50/50%
If the measure is in the Right leg, itā€™s not illogical.

However, yesterday I was in my Neo for a small training and the power was opposite: Average 150w with the Neo and 158W with the P2Mā€¦
The only difference between the other days was my shoes ! Maybe the adjustment of my shoes are different, but the result is completely opposite.


Question: When you calibrate your P2M, what is your number? Is it a negative number like -50? Or positive number like 90?
Do you know the correct range for a good calibration? Example: -200 to 200?
Thank you in advance
Thierry
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Re: Power2Max calibration questions [Eltito] [ In reply to ]
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P2M Eco is a two sided power meter. It's futile to compare to your trainer for reasons that trainers do not have real power meters with strain gauges and stuff... They are in the ballpark but not anywhere near precise. They are also susceptible to heat variations and numbers will drift etc... So you should really run the trainer spindown protocol after 10-15 min of riding to minimize this. So...forget trainer power.

The offset # you get after you zero the PM doesn't mean anything. It's different for every power meter that leaves the factory and will vary slightly from day to day based on temperature and other factors. For example, I get -48 > -50 on my P2M when I zero it and used to get 9 on my P1 pedals. Numbers should be close from one day to another.
It's not a real calibration, the real calibration is done by using a known weight hanging from the crank and measuring the torque value... It's done at the factory and should not need to be repeated.

In my experience (I have the NG) the numbers compared to P1 were withing 2-4W but then again my P1 pedals were junk and needed repairs two times. Also many people reported slightly inflated numbers with P1 pedals. Might also have to do with the point of measurement (crank tip vs spider).

For a better comparison try to do the following: zero the P1s and the P2M. Warm up the trainer and do a spindown then try to see what you get. I would still trust the Power2Max over the other two especially the Neo.

Eltito wrote:
Hello
My name is Thierry, and Iā€™m new here and please in advance: sorry for my English.
I understand very well this subject because I have the same ā€˜ā€™problemā€™ā€™ (or simply: ascertainmentā€¦).
Maybe itā€™s not a true problem, but I would like to understand why the power of my P2M NG-Eco is 4 or 5% less than my Tacx Neo and that my Powertap P1ā€¦.
First of all, I think the measure is take only in the right leg with the P2M Eco and in the right and left legs with the Neo and the P1.
For my example: With the P1, I have always L-52%/R-48% or 51/49%. Never 50/50%
If the measure is in the Right leg, itā€™s not illogical.

However, yesterday I was in my Neo for a small training and the power was opposite: Average 150w with the Neo and 158W with the P2Mā€¦
The only difference between the other days was my shoes ! Maybe the adjustment of my shoes are different, but the result is completely opposite.


Question: When you calibrate your P2M, what is your number? Is it a negative number like -50? Or positive number like 90?
Do you know the correct range for a good calibration? Example: -200 to 200?
Thank you in advance
Thierry

What's your CdA?
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Re: Power2Max calibration questions [trailerhouse] [ In reply to ]
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Thank you for your very precise answer.
Oddly tonight, the results were between 0 and + 2w for the P2M with several series with different powers.
So, I did not understand why the first 2 days, the results were not very good.
I will test again and come back to tell you.
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Re: Power2Max calibration questions [Northy] [ In reply to ]
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I received today an answer from P2M. He told me, the main thing is to have already for each calibration a number between +10 or -10 than the last calibration.
Yesterday I had 91, and today 86.
I'm happy ;-)
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Re: Power2Max calibration questions [Eltito] [ In reply to ]
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So I am having low readings. When I calibrate it reads -110.

Any tips
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