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".

Thanks Claus. Will read the article in full a bit later on.

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Exp001

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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Michael - The Anaerobic Threshold is neither...

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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Just ride ..

Latest update on the Vector: http://www.metrigear.com/

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

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.

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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http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

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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http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

interesting.....

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

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

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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http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

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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http://djconnel.blogspot.com/
Fuji SL/1
Send your data to Weight Weenie listings!

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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2013 Wilier Cento1 SR || 2009 Ridley Crossbow || 2011 Yeti AS-R 5 Carbon

Interesting power meter user survey on brim brothers website.

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