Kickr Core - anyone having power output problems?


A bunch of us ride regularly in group rides out on the road and on Zwift with WBR, AHDR etc. One of the group - Aleck - has just started on Zwift using a Kickr Core (the rest of us have standard Kickr’s of varying ages) and he is having real problems keeping up with the group. The thing is he is the strongest rider out on the road by far and can put out the most watts in real life. This has been going on for the last few weeks and despite doing regular spin down calibrations on the Kickr and making sure it has the latest firmware etc. it isn’t getting any better.

The on-screen wattage looks about right and the .fit files seem to record the right sort of wattage - however he is putting so much effort into generating the wattage that he is dying half an hour into the ride and dropping out of the ride. I have compared his Zwift fit files from this mornings Volt ride here -

It’s almost as if the Kickr has the brakes on it - any ideas what to try next, other than fitting a power meter to his bike to see what it thinks he is outputting ?


sorry for such a simple response, but does he have his weight correctly entered?

also, i think the time trial bike doesn’t do drafting, so if you guys are riding fast, it might be hard to keep up.

Hi Dan, his weight is correct at 80kg and he is riding a standard bike. He is a 2nd cat road racer so should certainly be able to keep up with a 2.5 w/kg group ride.

Hey Graham, can you have your friend send us a support conversation and include his log files from those rides?

Link to support conversation:
How to find Log Files:

Did this get fixed? Got a friend with the same issue from the sound of it.

No, we never got it sorted. It has now happened to a few other friends with Kickr Core trainers. Some have sent them back for replacements, others have upgraded to full Kickrs. I now only know two people that have Core’s with the original problem so we worked out how to weight dope them down to get their w/kg correct. One is a 1st cat rider who weighs 73kg but we had to put his weight to 55kg on Zwift so he could be competitive in a C race !


Thanks for your reply