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PostPosted: Fri Mar 01, 2013 7:51 pm 
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That's due to the way the test was done: the "Cyclus2" measures the power where usually the rear wheel is, hence it doesn't allow to test wheel based power meters. The "Summary" states that "based on the data it can be assumed that the system is well suited for power measurements".


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PostPosted: Fri Mar 01, 2013 7:53 pm 
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Thanks Claus. Will read the article in full a bit later on.

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Posted: Fri Mar 01, 2013 7:53 pm 


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PostPosted: Fri Mar 01, 2013 8:58 pm 
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djconnel wrote:
Full agreement. There's some obvious engineering challenges, but the Pioneer unit does this.
Seems to me that with the relatively tall profile of Pioneers crank arm units, its not going to work with frames that have BB30/PF30 bottom brackets as many typically offer minimal clearance between the stays and crank arms.

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PostPosted: Sat Mar 02, 2013 2:17 am 
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Can anyone distill that german article by chance? Tried with google a bit to understand but still tough. Mostly curious about the difference\versus of SRAM(Quarq) and SRM

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PostPosted: Sat Mar 30, 2013 1:22 pm 
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Latest update on the Vector: http://www.metrigear.com/

Well, this is probably as informative on the subject as the Garmin site.


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PostPosted: Sat Mar 30, 2013 1:51 pm 
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A friend of mine is beta testing them, on a bike also equipped with a current production PM and two head units running debug software.
He reported some of the numbers to me on a ride and the two units seemed to be tracking pretty well.


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PostPosted: Sat Mar 30, 2013 1:56 pm 
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prendrefeu wrote:
I did not read the article in full yet and I plan to later today, but on initial glance it's interesting that the mag posted no accuracy readings nor variance for the PowerTap G3. Anyone know why?


They could have then compared the Powertap to the SRM, but they differ in whether drivetrain losses are included.

I'm really surprised at Quarq and Rotor results being so poor compared to SRM. I'd love to be able to read the article.

Actually, Quarq may be the winner here if comparison is to hub, since you expect drivetrain losses of close to 3%.

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PostPosted: Sat Mar 30, 2013 2:52 pm 
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In my blog post here I assumed 3% drivetrain loss and got the following ranking:

place power meter accuracy
1 Quarq/SRAM 0.6%
2 SRM FSA -2.5%
3 Rotor3D 3.1%
4 SRM Campagnolo -4.3%
5 Power2Max -5.0%
6 Look/Polar -7.0%
- Powertap ?

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PostPosted: Sat Mar 30, 2013 8:08 pm 
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interesting.....


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PostPosted: Sat Mar 30, 2013 9:40 pm 
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djconnel wrote:
In my blog post here I assumed 3% drivetrain loss and got the following ranking:

place power meter accuracy
1 Quarq/SRAM 0.6%
2 SRM FSA -2.5%
3 Rotor3D 3.1%
4 SRM Campagnolo -4.3%
5 Power2Max -5.0%
6 Look/Polar -7.0%
- Powertap ?



Ummmmmm, except the Cyclus 2 accuracy is quoted as +-2%.

http://www.h-p-cosmos.biz/en/systems/cos14368-01_id_cyclus2_en.pdf


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PostPosted: Sun Mar 31, 2013 3:19 am 
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Wow... So Quarq, Rotor, and SRM are essentially tied.

It occurred to me it would be funny if the ergo had been calibrated against an SRM (Science version, I'd hope).

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PostPosted: Sun Mar 31, 2013 5:10 pm 
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Even the science version of SRM isn't so good when tested against an absolute standard (reference from 1999, though).

I'm thinking now all we can conclude from this article is the different units disagree. Which is correct is up to the reader. For what it's worth the SRMs came out mid-pack.

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PostPosted: Sun Mar 31, 2013 5:22 pm 
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To complicate matters, my experience with the GXP Quarq S975 mirrors the long "Disappointment with Power Meters, mostly Quarq" thread on Wattage.

Damn thing was great 99% of the time but would randomly freak out and drift off to lala land. Most frustrating thing was that it wouldn't drift off by much. Maybe 10%. Enough to make it totally worthless but sometimes not enough to know for sure it was off. Was always second guessing it when the power number didn't exactly match my PE.

And yes, I zeroed it religiously.

Had much better luck with my PowerTap.

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PostPosted: Sun Mar 31, 2013 9:43 pm 
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Location: Hautes Alpes, France
Interesting power meter user survey on brim brothers website.


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Posted: Sun Mar 31, 2013 9:43 pm 


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PostPosted: Sun Mar 31, 2013 11:20 pm 
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One of my Power Taps has decided to drift off randomly. Called Saris and they are replacing it at no charge. (under 1 year old0


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