Which power meter: Sram Red + Stages or Quarq Dzero Sram

Discuss light weight issues concerning road bikes & parts.

Quarq v Stages

Quarq Dzero SRAM
78
91%
SRAM Red with Stages
8
9%
 
Total votes: 86

Shrike
Posts: 1198
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

leicaman wrote:Perhaps a stupid question but am I right in saying that the the Quarq SRAM red Dzero is compatible with etap? I have etap and don't want any nasty surprises when the power meter arrives.

Cheers


Yes but you have to buy the power meter etched onto the crank. You can't buy the power meter spider and install it yourself on a SRAM Red eTap Graphics crankset.

This will work:
https://www.quarq.com/store/item/1770/

Theres also an aluminium arm version, and a Quarq carbon version (same as Sram but Quarq logo instead). Both will also work.

Shrike
Posts: 1198
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

sd5500 wrote:
Shrike wrote:@Troy

are you not making 165mm SRAM eTap Dzero's?

Asked Wiggle and they said no, they won't be stocking any.

Is there anywhere that has a 165mm SRAM eTap Dzero GXP in stock if you are making them?


I just ordered that exact one (its 130 for my 53/39 rings) last night from clevertraining.com


Yeah some 130s around, but 110's aren't anywhere.
http://www.clevertraining.com/quarq-sra ... ower-meter

'Special order'

davidalone
Posts: 589
Joined: Fri Feb 10, 2012 4:27 pm

by davidalone

Delorre wrote:For me, Stages V2 have been performing really well for most than a year now: consitant, reliable, light and reasonably affordable. It's maybe not 100% accurate, but if consitant, that's OK to track own progress and do workouts based on power. I own a Drivo since last week, and seems Stages reads low on power, but being left side only, its possible my left - right balance is not 50 - 50 %, so nothing I can fault Stages for :wink:


The consistent but not accurate argument again, eh? no, it does matter.

Say your real L/R balance is 55/45. For simplicity sake, lets assume an FTP of 100 Watts, 55W left, 45 watts right Stages assumes 50/50, so it would read 55 watts left foot and multiply it by two- telling you your FTP is 110 W. Stages will OVER estimate your power by 10%. If you are using power to design your workouts- you'd be 10% over your required power all the time. would your intervals be effective then? Worse, if you're riding a time trial and pacing using power- you'd be going out 10% too hard, a recipe for disaster.

Now say you were 45/55 L/R balance. Assuming an FTP of 100Watts again, Stages now UNDER estimates your power at 90 watts. again, all your workouts would then be 10% below what you'd really need to hit, you'd be too conservative for your pacing. Considering stages is +/- 2% accurate you could be looking at as much of a 12% error.

granted, if your L/R balance is lower- say 42/58, you'd get less error, but your L/R can drift when you are fatigued, and it's been pretty much shown that MOST folks are not 50/50. Stages is also highly inaccurate for Short sprint intervals. if you ride track, A stages is not going to give you good data.

For most people, a stages may be 'good enough', but unless you know your true L/R balance you won't really ever know. If you're already spending $700 odd on a stages, why spend so much money on an imperfect product?

kulivontot
Posts: 1170
Joined: Sun May 16, 2010 7:28 pm

by kulivontot

dataplz

raven14
Posts: 27
Joined: Sun Oct 18, 2009 7:27 pm

by raven14

davidalone wrote:The consistent but not accurate argument again, eh? no, it does matter.

Say your real L/R balance is 55/45. For simplicity sake, lets assume an FTP of 100 Watts, 55W left, 45 watts right Stages assumes 50/50, so it would read 55 watts left foot and multiply it by two- telling you your FTP is 110 W. Stages will OVER estimate your power by 10%. If you are using power to design your workouts- you'd be 10% over your required power all the time. would your intervals be effective then? Worse, if you're riding a time trial and pacing using power- you'd be going out 10% too hard, a recipe for disaster.

Now say you were 45/55 L/R balance. Assuming an FTP of 100Watts again, Stages now UNDER estimates your power at 90 watts. again, all your workouts would then be 10% below what you'd really need to hit, you'd be too conservative for your pacing. Considering stages is +/- 2% accurate you could be looking at as much of a 12% error.


This is not true if you use the same Stages PM to perform the workouts; you will be in the right powerzones although inaccurately measured. Of course, swapping to another (L/R) PM there will be a substantial discrepancy. But then again measurements will differ between any PM (although hopefully not by 10%).

gurk700
Posts: 58
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

Excuse my weak legs. But here's 2 rides. First one with Stages Duraace version 2. Second with Quarq DZero. Exact same route except where I hit start and stop is off by a few seconds. Elevation discrepancy is cause of my Garmin. You be the judge!

Image

raven14
Posts: 27
Joined: Sun Oct 18, 2009 7:27 pm

by raven14

So many other variables (bike/wind/position/temperature/...) that you can't draw any conclusion from the data.

Shrike
Posts: 1198
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

You can conclude that no significant discrepancy is currently apparent.

moonoi
Posts: 417
Joined: Sat Nov 21, 2015 3:04 pm

by moonoi

Average power is a useless measurement to determine the accuracy of a power meter


Sent from my iPhone using Tapatalk

gurk700
Posts: 58
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

Clearly the only we can really be sure of the accuracy is testing it in a lab situation. has this been done before? it there a power meter accuracy test out there? All I've seen is comparing one PM vs another in those youtube tests.

moonoi
Posts: 417
Joined: Sat Nov 21, 2015 3:04 pm

by moonoi

Take a look at how Ray Maker does his PM testing, there is probably no more accurate testing methodology in a real world environment than what he does.


Sent from my iPhone using Tapatalk

davidalone
Posts: 589
Joined: Fri Feb 10, 2012 4:27 pm

by davidalone

raven14 wrote:

This is not true if you use the same Stages PM to perform the workouts; you will be in the right powerzones although inaccurately measured. Of course, swapping to another (L/R) PM there will be a substantial discrepancy. But then again measurements will differ between any PM (although hopefully not by 10%).[/quote]

That assumes your L/R remains the same on a day to day basis, with fatigue, and at different levels of intensity. The moment you swap power meter, you're also screwed. your previous data becomes pointless.

THe point is, you're already spending already circa 700 dollars on a stages. why not pay 100-150 more for a power2max, or a powertap?

kulivontot
Posts: 1170
Joined: Sun May 16, 2010 7:28 pm

by kulivontot

Show me real data that lr balance changes on a day to day basis otherwise I will continue to consider this a strawman argument.

moonoi
Posts: 417
Joined: Sat Nov 21, 2015 3:04 pm

by moonoi

Well I got bored waiting for my repaired/replacement Quarq and bought a Stages, so far I'm very happy with it and the data correlates well with my Rotor Inpower in similar conditions


Sent from my iPhone using Tapatalk

User avatar
Pepsi
Posts: 206
Joined: Tue Feb 14, 2006 8:54 am
Location: Slovenia, Europe

by Pepsi

Is there a big difference in color (carbon structure) between Sram eTap cranck and Stages cranck?

Is it possible to remove Stages logo from Stages cranck?

Post Reply
  • Similar Topics
    Replies
    Views
    Last post