Kickr Core v1.4.8 not dropping to zero and power is too high

After upgrading to Kickr Core FW v1.4.8 and Zwift 1.60.0 (since Saturday 2024-03-09) there seems to be an offset on the power reported from Kickr Core. It is most noticeable when attempting to supertuck. The wattage does not drop fully to zero, like it used to do (at least not for several seconds), but seems to have a baseline offset of around 27W. My 20min avg from Kickr Core was 271W compared to 254W from Stages. I have done a lot of DRs and it has always been the other way around (Stages reporting higher than Kickr) and Kickr used to drop to zero as expected.

From yesterdays race: zwiftpower analysis set_id 412921 (my messed up numbers caused Zwift to bump me to B for at least 90 days).

Easy ride from Saturday with lots of coasting: zwiftpower analysis set_id 412608
One sample suggest that it takes 18 seconds to drop to zero.

Sample ride on v1.3.17: zwiftpower analysis set_id 411889

See more dual recordings at zwiftpower profile 3892276

I was planning to do some testing today, but of course there is no repro. I did power cycle the Kicker Core after the race yesterday, but I am 98% sure I also power cycled it after updating the FW to v.1.4.8 on Saturday.

Today (Analysis set 413210 over at ZwiftPower if you want to have a closer look) it drops nicely to zero and the Stages power meter reports higher numbers):

Zoomed in

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Have you performed a manual spindown with the wahoo app?

Yes, several times, but since v1.3.17 it will do auto spindown.

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Even though a manual spindown is still possible, there’s no way to disable the auto-spindown AFAIK so it will happen eventually

Hi, I’ve also had the same issue but with my Kickr V6, at first I thought I had good legs, but after a couple of rides I could see that my power meter wasn’t matching up, the higher the power the bigger the discrepancy and like you said it seemed to take longer than usual for the power to go down to zero. I’ve gave up and went back to a certified reconditioned V5 and it matches within 1% with my power meter. I’ve emailed Wahoo but just get the usual checks and tests to perform. I’m thinking it could be a software issue?

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It’s pretty clear the issue is with the Kickr V6

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Hi Stig,
It could be the belt has lost some tension over time.

Take the plastic cover off and nip the belt tensioner up around a full turn.

I am not sure how that would produce the issue in the initial post (power not dropping to zero), but the Kickr Core is brand new (since November 2023) and as already stated the problem has not reproed since Sunday (raced yesterday and did several supertucks ;))