P2M NG vs. NGeco - real-life accuracy difference?

Discuss light weight issues concerning road bikes & parts.
jfranci3
Posts: 354
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

bilwit wrote:
Tue Nov 06, 2018 7:29 pm
neeb wrote:
Tue Nov 06, 2018 7:18 pm
northwestern wrote:
Tue Nov 06, 2018 6:49 pm
1% of 300 ( assuming that's your FTP) is 3W. Not even the pros care about that.
Sure, but that was my point. 3w isn’t really significant but 6w is when measuring improvement or setting targets for intervals.
just put the Eco on all your bikes, problem solved 8)
You fool! That’s + or - 2%!!! One Eco will be 294, another 306! You’ll be in absolute agony over those 12w. Your friends will wonder why they never see the blue bike anymore. The blue bike will get fenders, bags, and a straight bar - all because you can’t bare the sight of 294w

by Weenie


Hexsense
Posts: 564
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

I think i remember when GCN visit Power2Max, they said the NG and NGeco 's hardware are built very much the same way.
Just that every piece of the NG got validated and fine calibrated out of factory. While the NGeco got randomly pick a few sample per batch to do quality check. Hence, they can't claim the same accuracy.

If that's true, most of the NGeco should be nearly as accurate as the NG. Except some few odd that might be off and didn't get caught because it wasn't sampled.

mag
Posts: 250
Joined: Thu Mar 16, 2017 12:23 pm

by mag

One more thing which may be of some importance is that (at least in the EU) the NG models are backed by the 5 year warranty instead of 2 years for the NGeco. But as for accuracy, those +/- 2% are mostly extremes. Typical accuracy will be better than that and good enough for most of us mere mortals.

cro2
Posts: 35
Joined: Fri Oct 13, 2017 7:39 am

by cro2

jfranci3 wrote:
Tue Nov 06, 2018 8:12 pm
bilwit wrote:
Tue Nov 06, 2018 7:29 pm
neeb wrote:
Tue Nov 06, 2018 7:18 pm
northwestern wrote:
Tue Nov 06, 2018 6:49 pm
1% of 300 ( assuming that's your FTP) is 3W. Not even the pros care about that.
Sure, but that was my point. 3w isn’t really significant but 6w is when measuring improvement or setting targets for intervals.
just put the Eco on all your bikes, problem solved 8)
You fool! That’s + or - 2%!!! One Eco will be 294, another 306! You’ll be in absolute agony over those 12w. Your friends will wonder why they never see the blue bike anymore. The blue bike will get fenders, bags, and a straight bar - all because you can’t bare the sight of 294w
That's not what reading accuracy means. The "2%" should be read as "the true value lies within 2% of the vale that you read on the head unit with a given probability distribution". This means that if one gets a 300 W reading then the true value lies between 294 and 306 W, but please note that the probability distribution is usually very much centered around the true value. This means that you are much more likely to be within a watt or two from what's indicated.

As I mentioned earlier the second to second fluctuations are likely to be much higher. I never really bother to hold a steady power output during training and in fact this is counterproductive in most cases. Physiological adaptations do not happen suddenly when a given wattage is achieved - it's a continuous spectrum really, so if your average power over an interval is X, it doesn't really matter if you held the power constant ot fluctuated slightly (as long as those fluctuations are small enough).

petromyzon
Posts: 269
Joined: Mon Apr 05, 2010 4:14 pm

by petromyzon

LR balance etc. is bullshit. But better calibration and validation, and three extra years of warranty, are absolutely key. Worth it no contest.

You could sweat blood for another 10W on your FTP. I understand cro2's point about a likely normal distribution of error but even if you are a small handful of watts out it is relevant.

jencvo
Posts: 19
Joined: Thu Oct 18, 2018 12:01 pm

by jencvo

Speaking of P2M, what's your opinion on Rotor's 24 vs 30mm spindle for it? I'm planning on upgrading to Power2Max and currently run Shimano's BB so getting 24mm would be easy, but I'm curious about your opinion. Getting NGeco, can't justify the price of NG.

cro2
Posts: 35
Joined: Fri Oct 13, 2017 7:39 am

by cro2

I use the 24 mm version, so far so good. I haven't noticed any flexing even when putting 1400+ watts during sprints. The 30mm version is a slightly lighter and more expansive considering the price of the crank and the BB.

robertbb
Posts: 550
Joined: Thu Jul 23, 2009 3:35 am
Location: Melbourne, Australia

by robertbb

petromyzon wrote:
Tue Nov 06, 2018 10:57 pm
LR balance etc. is bullshit.
Why? :noidea:
It's ALL about the bike.

RobertBB's CyclePlanner Spreadsheet:
https://weightweenies.starbike.com/foru ... 8&t=152263

TobinHatesYou
Posts: 1892
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

robertbb wrote:
Wed Nov 07, 2018 8:13 am
petromyzon wrote:
Tue Nov 06, 2018 10:57 pm
LR balance etc. is bullshit.
Why? :noidea:
In the context of spider-based PMs, it is bullshit / estimated / voodoo. I don't find it an amazing dataset with my Assiomas or Vector 3s, but it's fun to have.

robertbb
Posts: 550
Joined: Thu Jul 23, 2009 3:35 am
Location: Melbourne, Australia

by robertbb

TobinHatesYou wrote:
Wed Nov 07, 2018 8:29 am
robertbb wrote:
Wed Nov 07, 2018 8:13 am
petromyzon wrote:
Tue Nov 06, 2018 10:57 pm
LR balance etc. is bullshit.
Why? :noidea:
In the context of spider-based PMs, it is bullshit / estimated / voodoo. I don't find it an amazing dataset with my Assiomas or Vector 3s, but it's fun to have.
Oh I see. I keep L-R on my head unit, right under cadence. I find it interesting and it can help me keep proper technique on longer rides. :thumbup:
It's ALL about the bike.

RobertBB's CyclePlanner Spreadsheet:
https://weightweenies.starbike.com/foru ... 8&t=152263

bahn
Posts: 23
Joined: Thu Oct 10, 2013 7:42 am
Location: UK

by bahn

I had a NG fail on me because the USB connector broke. P2max tried to claim I forced the cable in the wrong way - I have mechanical sympathy so find it hard to believe I would be so agressive or clumsy... Because of the number of hours of use between charging then it took me about 10months to discover the charge didn't work. It was literally only the 2nd time I must have tried to plug the cable in. The metal surround around the USB socket is flimsy and I don't think that help ensure the cable sits securely in the socket as it sits there vertically. I ended up replacing it for an NGeco - I now have two and they are both flawless. I used to have a Type S and that was also flawless. The 5yr warranty is pobably the main sell, but you could sell on a NGeco every 2 years and still be up. Never had the battery cover pop off or come loose and I have raced and ridden in foul conditions - but I wouldn't jetwash it.

mag
Posts: 250
Joined: Thu Mar 16, 2017 12:23 pm

by mag

What I'd like to see (just out of curiosity) is some real world comparison between the true L/R balance and the estimated one by the P2M. Just to see how much off it could be and if it could be at least partially useful in some cases.

1415chris
Posts: 1110
Joined: Sat Apr 18, 2009 8:59 am
Location: Surrey UK

by 1415chris

In the relation to L-R balance the more interesting it would be to see how much inconsistency can be in the figures coming from single sided power meter-calculators.

mike
Resident Pro
Posts: 2515
Joined: Tue Mar 18, 2003 9:42 pm

by mike

i've owned the original, type s, and ngeco. all are perfect.

by Weenie


User avatar
euan
Posts: 1515
Joined: Sat Sep 05, 2009 11:20 am

by euan

Get the Eco and use the money saved to by an Android phone so you can update the firmware
"Step forward the climber and all those who worship at the altar of lightness" - R. Millar

Post Reply
  • Similar Topics
    Replies
    Views
    Last post