Matching up power meters

Yes! My bad! Im very tired and a little confused.

I suppose if they are compatible cranks you could swap them between bikes as single sided is relatively easy to swap (I bet they aren’t though??).

LOL! You bet right :slight_smile: One Shimano, one SRAM. I’m a tough case! Think I’m going to try to use Virtual Power as a constant and see what happens because I’m thinking it may actually work. That, plus I don’t know anyone in my area with a Kickr :wink:

I don’t think you’d necessarily have to do a full ramp test to get your comparison. You could just do your daily workout on the kickr using your phone to record data (paired to EITHER the kickr or your power meter on bike #1), and your garmin/whahoo/whatever head unit paired to the other device.

The next day you could simply re-complete the same workout but with bike #2 - again, with phone and head unit paired to EITHER kickr and the on-bike power meter.

To test whether you’ll get comparable data, your kickr info from day #1 and day#2 should be same/similar/close. Then all that’s left is to compare the power files from the bike #1 power meter from day 1 and bike #2 power meter from day 2. This comparison should tell you whether your two power meters are close. Again, the comparison of the kickr files from day 1 and 2 should tell you whether you’ll get reasonable data to compare.

I posted this morning about same problem between MTB and CX bike and different power meters. A post further up on this thread gave me this idea.

thanks,
eric

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You are basically right about any workout.

I specifically chose ramp because you need to know if it’s a % offset or a constant watts offset and a ramp is the best way to find this.

No real need to do ramp to failure. A few steps above threshold will do anyway… maybe 120-140% of FTP should be plenty really.

Interesting discussion and one I’ve thought about as I use 2 power meters with a Kickr. I did a similar comparison using the Kickr as a control and then doing a 10 min effort with my P2M and Team Zwatt power meters. Turned out the 2 PMs were similar but the Kickr was 10-12% higher, in line with other users experience.

There is also two points potentially being confused in the thread, one is comparing power meters, separate to this is how much power you can put out on a road bike vs TT bike.

  1. Different PMs - they need to read the same power to have consistent workouts in/outdoors. Once you know which PM is high/low you can adjust the offset (I know this is a feature on Quarq and Team Zwatt but not on P2M).

  2. The drop (or gain) in power on a TT bike then relates to having 2 FTPs with associated zones, there have been previous discussions on Facebook on this.

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In my case my TT bike is higher than my Road bike power.
But I’m thinking now that the longer crank arm on my road bike (172.5) compared to my TT bike (165) may be resulting in the lower output, until I adapt and increase the torque on the roadie.

Regarding adjusting offset, I have found this on Reddit https://www.reddit.com/r/Velo/comments/2xopxy/first_impressions_pioneer_power_meter_2nd_gen/

The Pioneer software has many methods to adjust the offset so you can match to other power meters. Cyclo-Sphere (their online Garmin Connect or TrainingPeaks equivalent) has three different ways to tweak the offset.

So I will investigate that to see if I can tweak it up to match my Rotor if indeed there is a discrepency

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It looks like Off-set adjustment in Cyclo Sphere can only be done to power files, not to the power that is being measured and displayed on head unit.