KICKR 2018 via Bluetooth intermittently missing ERG power changes

I started using The Sufferfest with my (then) KICKR 2018 (and KICKR Climb) in January and was very happy with how everything worked. 

Life happened, and I missed training for 6 weeks in March/April. Having come back last week, I noticed that my KICKR is now intermittently missing power changes perhaps 1 in 5 or 1 in 10 times. In case that's not clear, what I mean is that when the desired power value in the workout changes, sometimes the KICKR stays on the old value. I can either wait for the next 'scheduled' change in the workout, or hop off the bike, enter settings, and toggle ERG mode. Either way, it really destroys the flow of the workout for me.

My setup:

- Macbook Pro 2018 with MacOS Mojave 10.14.4 using built-in Bluetooth
- The Sufferfest app v. 6.0.7
- KICKR 2018 w/ firmware 3.4.68
- KICKR CLIMB w/ firmware 1.0.3 

This seems to have been a regression as I would have noticed it during January's training. I am aware that both The Sufferfest app and MacOS updated between when things worked and when they didn't.

Even if there's an underlying or difficult-to-fix issue with the underlying BLE communication, would it be possible to implement a "double-check" algorithm for power command changes to the KICKR? Specifically:

1. Send new ERG power value
2. Read current ERG power value from KICKR
3. If current value is not same as desired value, repeat ERG power command





  • Forgot to mention my Vector 3 power meter. One possible issue is that the batteries in the pedals are low and keep disconnecting and reconnecting. I wonder if these constant reconnects are causing BLE communication with other devices to be unreliable. Will replace these batteries this week and report back once I have enough time on the bike to judge if the issue is gone.

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  • Hi Chris,


    I believe that we are performing that check or one that is very close to it.  Still, there is a possibility of communication issues with Bluetooth especially if other apps are open that also want to connect to your devices. 


    Please do let me know how the battery change treats you.

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  • Hi Cody, I am having he same issues as Chris here on a Kickr18.  I notice that for the very short intervals (especially the red ones) I get a very short time at the prescribed power target.  Sometimes it doesn't hit it at all and i end up spinning out hard in anticipation of it getting harder.  Then sometimes it will go up to the power target and stay there through the rest period between the next interval - depriving me of the 10 second rest i so desperately need lol.

    I also have latest firmware on Kickr18 and using it for cadence and power.  

    I do also connect the trainer to a Garmin Fenix 5 and sometimes i also connect to Zwift but use a separate ANT+ dongle. 

    Sorry Chris I didnt want to Hijack your post, I just thought I would add it here as I seem to have the same issues.  I will remove and post somewhere else if its not appropriate for me to comment on your thread.

    Cheers, Matt

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  • Hey Matt,

    The short intervals do require some "spinning up" in order to not get buried.  With that said, they should let up pretty quickly once the interval is over.  Ant+ tends to do this a bit more slowly than Bluetooth... Chris's issue aside as it is a rarity from what I see in support.

    To both of you, I think we also need to factor in the length of the intervals that are giving you trouble.  If we are talking 5-second intervals I'd recommend using Level mode.


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  • Chris,

    You aren't using your Garmin's for power, are you?  

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  • I have a similar problem with my Elite Direto X.

    Yesterday I did my first training on Sufferfest, I did the "Angels".

    I know that Direto is known for handling ERG not very well, but actually, during mid-long intervalls there is no problem at all. However, short sprints or speed-ups just don't work, the trainer is not able to provide the requested resistance/power quickly enough. 

    When I read here, that this is a problem with other trainer too (Kick), then my conclusion would be, ERG is not suitable mode for such short intervalls.

    Another problem for me was, the whole training was just... too easy for me. Only the second "climb" felt somewhat hard. I gave correct FTP in the settings, and in other apps it seems to work.






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