SRAM RED 22 Quarq

Discuss light weight issues concerning road bikes & parts.
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heliwasp
Posts: 10
Joined: Fri Jun 05, 2015 5:44 am
Location: Switzerland

by heliwasp

Hi - I usually have my bike inside my house and would do the zero calibration just before I go outside. The outside temperature may be 5-15 Celsius lower compared to the inside temperature. If I understood correctly, latest sram red 22 quarq powermeter do support active temperature compensation. Does that mean that that my procedure should be fine and there is no longer any need to do the zero calibration at the outside temperature? How well does that temperature compensation work in practice?

by Weenie


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Rick
Posts: 2004
Joined: Sat Aug 29, 2009 4:30 pm

by Rick

I am just guessing, but based on the way strain gages usually operate:
You want to calibrate in an environment where the temperature is stable and not changing.
If there is software compensation for temperature change then you assume that the software operates correctly so long as the initial calibration is correct at the calibrated temperature.
So in your case I would think that you want to calibrate indoors (stable temp) and not when you first go outdoors, where the temperature of the components may be rapidly adjusting.
After you have been outside for long enough that the temperatures are all stable (30 minutes ?) then you could recalibrate if you wanted to.

goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

I have a new Quarq Elsa RS with the 10k temp compensation. As I understand it, Quarq takes each pm and runs them through a temperature change and plots 10k points that are programmed in the firmware. So, as the temperature changes, the firmware applies the correct compensation based on actual test results for that specific pm.
At first, I did not change my routine from my previous version of the quarq that did not have this feature. I usually just pedaled backwards 4 times a couple of times to initiate the auto zero during the ride. At the end and beginning of the ride I did the zero offset via my Garmin Edge. The calibration number reported back has been -60 to -65, so very little variation from very cold days to hot days. So, basically, the 10k compensation works to minimize the drift in numbers. My old quarq tended to drift up to 30 units depending on conditions. From these results I am pretty confident that I can relax this regime and going forward I usually do a zero offset once during a ride, if I remember, and then check the zero at the end of the ride.

There's a good writeup with some graphs in DCrainmakers blog. Here's the link:

http://www.dcrainmaker.com/2014/08/eurobike-powerbeat-infocrank.html#quarq-power-meters

I also asked Quarq on the Wattage forums. The simple answer is that it minimizes the need to perform zero offset calibrations going forward.

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