4iiii watt VS kickr core

So i did a test on kickr core in erg mode My 4iiii always 10_25 watt higher… How can this be?

There are several things at play here that you should consider.

  1. Did you calibrate both after 10-15 min of riding?
  2. The Core is measuring at the “wheel” vs the 4iiii is measuring at the crank so any drivetrain loss will show up IF they ever would give you exactly the same result.
  3. Is the 4iiii dual sided or single? If single then it is simply doubling the power of your left leg. The Core is measuring both legs. If your left leg is stronger than your right then your 4iiii power number will be slightly inflated.
  4. Are you using the Wahoo power smoothing? Your Core can be set to do this or not in the Wahoo app. Smoothing this and not the 4iiii will for sure mean the numbers you see on the screen are different.

In the end they will rarely if ever match and it doesn’t really matter that they do. What matters is that you train using a consistent source of power be it the 4iiii or the Core.


Different power meters. The 4iiii is crankarm based, while the Core is measuring power in its hub. Typically the farther from the source (your legs) you go, the gradual loss of power occurs when measured. So, seeing a higher power measurement from your crankarm would make sense. But also, these are different devices, made from different manufacturers, and neither is perfect.

The key thing for you is not accuracy, by consistency. Do your tests and your training as much as you can with the same device, calibrate when required, and compare your improvements with apples to apples, not apples to oranges :slight_smile:

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My Kickr 2017 power estimates drift after it warms up. Definitely recommend doing a spin down after 10 or 15 minutes if you want to increase accuracy of Kickr power estimates.

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it’s your drive train. thats all

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I bit late to this party and anecdotal but I just switched to this set up, from a snap to core while using 4iiii left crank only with power match. Messed around with it last night calibrating etc, Core registered lower and changes slower as expected, not as slow as the Snap. Did a ride this morning and was very impressed with the feel of the Core, no real off periods on wattage with ERG that I got from the snap. I continue to just run with what the PM tells me as did before, but IMO this is a nice setup.