ERG vs Level Mode Differential

Rode in Level mode 2 using Wahoo Kickr. Also use my Garmin Edge 520. I set up the ride using only Wahoo Kickr readings [power, cadence, speed]. In ERG mode the readings are the same for power, speed and cadence on the Kickr and Garmin when riding in ERG mode. However, in level mode, the Garmin power average [1 hour ride] was 5% higher than the Kickr power reading and the speed was 5km/hr higher than the Garmin. Any ideas why?

here you have an explanation

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Just to clarify: when you say the “KICKR reading” do you mean the number shown on SYSTM or something else?

Display on screen. Did Systm base ride, 1hour and 10 minutes.

Was the average / np for the entire ride, also different ?

Average cadence 88 rpm for both

np = normalised power

Garmin 150 n
SYSTM 137 np

Is your Garmin reading power from the Kickr or a different power meter?

Has this happened on just one rider or many? Did you start and end recording on the Garmin at exactly the same time as the workout on SYSTM?

The Garmin is reading from the Garmin power pedals. I have mostly ridden in ERG mode. However this occurs whenever I ride in Level mode.

Are you on the most up to date firmware on both pedals and Kickr?

I believe so but will need to check

I’d check that first. Level 2 is fairly hefty on a Kickr so potentially the flywheel speed might have been low, and I think the most recent Kickr firmware update addressed power discrepancies at low fly wheel speeds. You could also try on Level 0 or 1 and a bigger gear and see if that is any better. Failing all that I would contact Wahoo.

Thank you and will do

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No problem. Keep us updated with how you get on.

Ok👍

Different power meters give different readings. This is especially true when you compare power meters that measure at the pedal (or crank or spider) like the Garmin pedals and power measures at the rear hub which is essentially what the KICKR does. I am completely unsurprised by the difference between the Garmin and KICKR power readings in level mode. I’m more surprised by the lack of difference in ERG mode and wonder if your head unit and SYSTM happened to be picking up the same power meter in that instance.

Before I ride I calibrate the power pedals so that the Garmin can read it. When I launch the ride I enable the Kickr settings for power, cadence and speed and I disable the Garmin power, cadence and speed

If the Garmin pedals drops I get no reading on the Garmin Edge

I set up the training ride [SYSTM/Sufferfest] and use KICKR for cadence, speed, watts] and disable the Garmin speed, cadence, watts.