DFPM calibration not stored with profile

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kylef
Posts: 25
Joined: Mon Feb 16, 2009 3:22 pm

DFPM calibration not stored with profile

Post by kylef »

It appears the calibration value for a DFPM (the PCal value) is stored globablly and not per profile. When I switch profiles between bikes with DFPM I need to also go in and perform another calibration.

I'll admit that doing a calibration on every ride is important. Still, the iaero should store this value on a per profile basis.
coachboyd
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Joined: Thu Mar 27, 2008 7:01 pm
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Re: DFPM calibration not stored with profile

Post by coachboyd »

Things with a strain gauge can change day to day based on temperature, barometric pressure, and other factors. With this you have to find the calibration or zero the sensor everyday (and if the temperature varies on your ride), otherwise your stored calibration number will not be accurate the next day.

I believe it's recommended with every power meter to zero out before starting your ride.
Boyd Johnson
http://www.boydcycling.com - high performance carbon wheels and accessories
kylef
Posts: 25
Joined: Mon Feb 16, 2009 3:22 pm

Re: DFPM calibration not stored with profile

Post by kylef »

I don't disagree that a calibration should be done for every ride. That doesn't mean the calibration value shouldn't be stored in the profile. I can give a couple reasons for this.

The SRMs I've got have significantly different offset values. If I start a ride with SRM #2 using SRM #1's offset, the numbers will be completely bad. Sure, they may also be bad if I started with an uncalibrated SRM #2 offset, but at least they're in the ballpark. The SRMs I've played with are decent at maintaining their offset. The SRMWin software can correct for a bad offset (I think). I'm not aware of how to do this with either iBike or WKO+.

Knowing the previous offset is also useful. When you switch from SRM #1 to SRM #2 and do a calibration, you no longer have a (valid) previous offset. It's valuable to know the old previous offset. Large deltas may help identify when things are about to go amuck or running a second offset will be of value.
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