Too many PowerMeters - looking for advice from others with multiple PMs

#1

Seeking some input from others in Sufferlandria who own multiple bikes and PMs.
I have a Kickr core and two road bikes both running 4iii left side PMs.

I’m seeing some significant differences between my Kickr and my 4iiii PMs (not surprising) and I’d like to use the 4iiii’s instead of the Kickr’s PM indoors (while keeping ERG mode etc.).

It seems the easiest way to do this is the “control with ant+ power meter” option in the wahoo app. I’ve tried this plugging in the 4iii’s ant+ number, but it doesn’t feel like the Kickr is actually getting power from the 4iiii, i know this as

  • I tried doing some 1 leg drills and the power didn’t drop when not pedalling on the left side
  • running my Elemnt concurrently *on actual power not averaged and it showed some differences of 10-20w (note: i intentionally haven’t paired this with the Kickr). I mean not huge differences and i can compensate for, but I’d rather not need to spin down etc all the time

I went to do a half-Monty today to rejigg my power numbers based on the 4iiii indoors but wasn’t at all confident the Kickr was using the 4iiii

How do others setup in this kind of situation, any advice would be much appreciated?

#2

Before Wahoo got rid of the “control with 3rd party power meter” in android that worked well for me. Fortunately, there is close to no difference between my Kickr and my power2max power meter.

My advice to you is this…

Use your Kickr for your power for SUF, but record your indoor ride with your head unit (eg Garmin) using your 4iiii power meter for the data. When you do FF you can just use the “peak 5s/1min/5min/20min” data from your Garmin to set your outdoor FTP if you want.

SUF will only use the power from the trainer, so you should always use that with SUF, but you can easily record the data on your Garmin, and just don’t upload your SUF ride to Garmin Connect, Training Peaks etc, but upload to those places using your Garmin which is using your 4iiii data.

Does that make sense? Works well for me.

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#3

Thanks Ross, good idea you share there

#4

I have a Kickr core (on second). and have been through 2x4iiii pm’s, one stages and now on a Quarq.

I’ve had lots of trouble over last few years getting things to be comparable. I had a 4iiii like you and a core. As pm left only I decided I’d trust the Kickr I did lots of power testing and compared the two values on Excel then used scale factor on 4iiii to make them match. Worked perfectly. Then Kickr made funny noise and I got a new one. The new one still matched the 4iiii within 1%. Making me even more confident in the Kickr as it was now two kickr’s.

Then the 4iiii broke. I got a new one under warranty but that was as much as 20% off from the Kickr. Got a refund and tried a stages. That was close to original 4iiii but can’t scale it. So I sold it and got a quarq as it measured both sides being on the spider.

Right out of the box it’s within 1% of the Kickr. I’ve now set the Kickr to be controlled by it. But readings are always so close I have no idea if it’s doing it or not!

In summary I’d trust the turbo then try and scale both 4iiii’s to match each other and the turbo. As it’s one sided I wouldn’t try and control the turbo with it.

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