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Quarq post - pre ride calibration drift

 

   


vnet

Jan 12, 13 21:51

Post #1 of 13 (2574 views)
Quarq post - pre ride calibration drift Quote | Reply

(Good afternoon,

I am currently not confident on the power results that my quarq is giving me.

I have decided to check the value pre and post ride value given by my garmin 910xt. (before to do this study I have put a new battery)

The results are the following so far:
date pre-ride post ride length of ride outside condition comments
05/01/13 -98 -111 1h30 sunny 26C
06/01/13 -93 -110 4h30 sunny 26C
09/01/13 -93 -803(!!!) 1h00 sunny 25C the data started to be wrong after 25 mins
12/01/13 44 -95 2h20 sunny 29C
13/01/13 9 -94 4h00 sunny 22C

Has someone experience such a big variation with it quarq? If yes did you send it back to quarq under the warranty?

Thanks,

Vince


echappist

Jan 12, 13 22:01

Post #2 of 13 (2563 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

 
sign up for the wattage forum and read these four threads:

https://groups.google.com/forum/?hl=en&fromgroups=#!searchin/wattage/quarq$20drift/wattage/SAYz6itbAlQ/5mOXktng8qAJ


https://groups.google.com/forum/?hl=en&fromgroups=#!searchin/wattage/quarq$20drift/wattage/JUxaICGmYaA/Ze-8IztgzOgJ


https://groups.google.com/forum/?hl=en&fromgroups=#!searchin/wattage/quarq$20drift/wattage/9GUTjK84Ed8/JKuvUmOCJUIJ

(This post was edited by echappist on Jan 12, 13 22:06)


vnet

Jan 13, 13 1:52

Post #3 of 13 (2515 views)
Re: Quarq post - pre ride calibration drift [echappist] [In reply to] Quote | Reply

thanks for that.

That doesn't really inspire me confidence on my quarq. Should have sticked with my powertap or go to SRM.


echappist

Jan 13, 13 7:01

Post #4 of 13 (2448 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

vnet wrote:
thanks for that.

That doesn't really inspire me confidence on my quarq. Should have sticked with my powertap or go to SRM.

for a N=1 experience,

my Quarq was great in dry conditions. and if that's the condition in which you ride, you should be fine for most of the time.

the new Sram Quarq Red is apparently a bit better, though i don't know for sure.

Just remember that with an SRM, you have to swap the battery every 1900 hours (claimed). who knows how long the batteries really last...


vnet

Jan 15, 13 16:14

Post #5 of 13 (2341 views)
Re: Quarq post - pre ride calibration drift [echappist] [In reply to] Quote | Reply

Does any one knows what is the difference between calibrating the quarq with the Garmin and the backpedalling?

Thanks,

Vincent


jackmott

Jan 15, 13 16:16

Post #6 of 13 (2338 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

The backpedaling can introduce error due to freehub drag. It is better to do it with the garmin, but obviously less convenient.

If you do the backpedal method, doing it a lower speed reduces the drag.


vnet wrote:
Does any one knows what is the difference between calibrating the quarq with the Garmin and the backpedalling?

Thanks,

Vincent



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notaero

Jan 15, 13 18:32

Post #7 of 13 (2274 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

I recommend you to superman it for 10s with both feet clipped out and crank arms parallel to the ground while you are calibrating. Recommend you also turn off manual zeroing. Get into the habit of zeroing before any important intervals. The consistency of your numbers leads me to think the 8xx was an outlier caused by feet on the pedal applying force to the cranks when zeroing. Just a guess, hope that helps and sorry if it's all obvious stuff.


J_R

Jan 15, 13 18:41

Post #8 of 13 (2265 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

The -803 looks funky, but everything else seems OK. If memory serves me correctly (per Quarq) any pre-post delta of 50 or less is within spec. I think you are OK. Remember, your manual calibration should be with cranks in 12/6 o'clock position. I always put drive side at 6 o'clock.


EDIT - if new, it takes a few rides for the zero numbers to settle in. Quarq guy told me getting up out of the saddle and doing a few hard sprints can help speed up the settling in process.


(This post was edited by J_R on Jan 15, 13 18:46)


vnet

Jan 15, 13 19:08

Post #9 of 13 (2242 views)
Re: Quarq post - pre ride calibration drift [notaero] [In reply to] Quote | Reply

The calibration is always done whith the crankside at 6 o'clock without beeing clipped when I zeroing.

The manual zeoroing is also turned off.

I will carry on my log as I still do thing I have got an issue with this unit


durk onion

Jan 15, 13 19:26

Post #10 of 13 (2224 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

The zero offset value is affected by temperature. All of those differences seem to be pretty normal. Do you keep this in your garage where it's hotter than outside? The one from 09/01/13 is definitely funky though.


Tom A.

Jan 15, 13 19:32

Post #11 of 13 (2217 views)
Re: Quarq post - pre ride calibration drift [vnet] [In reply to] Quote | Reply

vnet wrote:
The calibration is always done whith the crankside at 6 o'clock without beeing clipped when I zeroing.

The manual zeoroing is also turned off.

I will carry on my log as I still do thing I have got an issue with this unit

For your log, I would recommend recording the ambient temperature of the area the bike is stored in prior to your rides and then, if possible, record the zero offset value from a manual zero after riding the bike for 10-20 minutes in the riding conditions.



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Pantelones

Feb 4, 13 16:54

Post #12 of 13 (1989 views)
Re: Quarq post - pre ride calibration drift [Tom A.] [In reply to] Quote | Reply

Tom,

Do any of the garmin units record the zero offset or calibration value in the ride file? I'm having some issues with my quarq unit and would like to look through the historical offsets... I calibrate regularly through the ride but my memory is shit.



Rant: It takes 17 button presses on my 910xt to go from data screen=>calibrate=>data screens. FUQ!


Tom A.

Feb 4, 13 16:57

Post #13 of 13 (1984 views)
Re: Quarq post - pre ride calibration drift [Pantelones] [In reply to] Quote | Reply

Pantelones wrote:
Tom,

Do any of the garmin units record the zero offset or calibration value in the ride file? I'm having some issues with my quarq unit and would like to look through the historical offsets... I calibrate regularly through the ride but my memory is shit.



Rant: It takes 17 button presses on my 910xt to go from data screen=>calibrate=>data screens. FUQ!

I don't think any save it AFAIK...that said, when I've wanted to record offset values during a ride, I usually just whip out my cell phone and take a picture. It's pretty easy to erase them later ;-)



http://bikeblather.blogspot.com/

   
 
 
 



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