Variable watts with Kickr Core

Hi everybody,

I am not sure this is a bug, but I really need to ask you.

I was training with an Elite Novo Force (for first time in Zwift) for around 20 days, and finally I have bought a Kickr Core and just trained with it for 3-4 days.

I have the feeling that watts are so variable: I am not able to keep constant watts. They are always changing up and down. Do you think this is normal? Maybe I can upload my fit file to anywhere so someone can check it please?

  1. Is it normal? 2) Problem with bluetooth? (ANT+ solves this?). 3) Problem with Core?

Finally: with Elite Novo Force, I was able to keep 220-230w. Now I only can keep 160-170w. Is this normal? Elite Novo Force was in resistance 3 as Zwift told me… Is it normal to have these differences between trainers? Keeping in mind that Novo Force was not an interactive one.

Thank you so much! I am new here but really excited about all this!

Hello @Guiem_Julia8685 and welcome to Zwift forums,

I also have a Kickr Core that I purchased right at the end of December upgrading from an old fluid trainer. I found that my power and FTP increased vs my old wheel on “dumb” trainer. It will be a different feel as the smart trainer reacts and changes resistance based on what Zwift is telling it (flat road, inclines and declines,etc.) when your wheel on trainer was a constant resistance no matter what Zwift was doing and the only way you could change resistance was to change gears.

I had numerous issues with bluetooth and started using ANT+ about 6 months ago and found it much more stable with hardly ever any dropouts. I think I’ve only had two or three signal losses since switching to ANT+, when I had Bluetooth I was having numerous dropouts during every ride.

The Kickr is probably fine, have you updated the firmware using the wahoo utility app on your phone? Also, make sure you do a spindown on a regular basis at least once a week after warming up the Kickr for about 10 minutes. Sometimes I just do this after a ride so it is ready for the next time.

Have you tried any workouts or using ERG mode? ERG will keep the power constant depending on your cadence, so if you pedal slower it will increase resistance to hit the target watts. This is great for workouts and training plans.


1 Like

Hi @Mike_Rowe_PBR, thank you so much for your replay!

I have opposite change: from 220 to 165 aprox. Maybe 165 is ok and 220 was bad (I used Elite Novo Force with an speed sensor in my rear wheel). I think I set up everything well, this is why I am surprised by the change and asking here if this is possible.

Keep in mind I don’t have drops in signal, just watts are swinging up and down. Where can I upload my fit file so anyone can confirm me if this is normal or not?

Yes, updated firmware and did the spindown after 10 minutes. I did spindown on wahoo (not in zwift), but I think this is the best.

Yes! I like so much ERG mode. And I don’t see any problem with it. I think I will do a lot of workouts on next weeks.

Anyone can help me with fit file?

Thank you!

older classic “dumb” trainers usually over estimate power, so your FTP was most likely higher than it should be. How long have you been cycling? I would trust the Kickr numbers more than the novo.

I think this is not what I need. It is for uploading log file (info about zwift system and status), not about my training (fit file). I have uploaded log file and no watts there.

I wasn’t training for several years now. I am not really trained, so 165w is ok for me. But confused about the change.

Keep in mind I am 89kgs, so 165w is only 1,85 w/kg. But it can be true :slight_smile:

Welcome to the forum.

You can give us a ling to Strava if you upload your files to Strava, then people may be able to see your fit file.

1 Like

Hi @Gerrie_Delport and thank you.

Strava is new for me too. Can you see the watts analysis here?:

If you can, please take a look at this part please: watts

If you zoom it you can see watts changing from 180-140-160-175-150-… almost every second. Is this really ok? Or I have a problem with anything?


1 Like

It is hard for me to say if it is normal, It does not look crazy, so nothing pop out for me.

It can be that you just need to get used to the trainer, and change gears to get a smooth pedal stroke.

Maybe @Mike_Rowe_PBR can compare to his rides since he also have a kickr.

Was that a workout in ERG or just a free ride?

It was an FTP test. So there are parts with ERG (and you see constant watts) and “free” zones.

I’m almost sure it is not about my pedal stroke… But maybe this is normal…

1 Like

seems to look normal to me and pretty consistent with what my numbers look like as far as fluctuation of power. I do see some spikes which could be caused by a signal dropout. I would suggest trying to get your cadence up a bit higher, see of you can average closer to 90 in the same gearing for an interval and see how that relates to more power.

1 Like

Thank you. Now i am more comfortable.

1 Like

I have a KICKR Core and had the same issue yesterday. I could pedal consistently and the watts were all over the map. Today the KICKR isn’t transmitting speed or power to Zwift or the Wahoo app :frowning:

Hi Daisy,

If Wahoo app doesn’t get the watts… it seems like a problem with KICKR. I think they have a technical support system at their web, take a look.

I am ok with KICKR now: watts are changing up and down, but it seems normal. And most important: it works really fine in Zwift and I don’t notice strange things.

Good luck with your KICKR!