FIXED: Trainer Resistance Issues (Mainly on iOS Devices)

Hey Zwifters!

Update #3

As you may have noticed there have been some significant resistance issues via BLE lately for several trainers, including: Elite Direto, Wahoo Kickr, TacX Neo, and a few other lower frequency cases.

We’ve noticed that most cases are on iOS devices as well. So, what we’ll need from you if you send in a support conversation:

  • Your exact trainer (including the year if applicable)

  • The device you’re using to run Zwift

  • BLE or ANT+ connection?

  • Zwift Game version

  • Trainer Firmware

  • Sim or ERG mode

Thank you all so much for your patience while we continue to investigate these issues. I will update this post as we receive new pertinent information.

Temporary Workaround: Not really a Bluetooth workaround, but ANT + is reported to work well with these devices still. Will update with more info as I receive it.


Hi Vincent,

I’ve had the resistance issues via Bluetooth on two trainers I have used. Happened on the previous IOS version and the most recent update, v1.0.30327. It appears at random and I cannot pin point what may be causing the issue. When it drops the resistance the units are all paired correctly in the pairing screen.

I am also using a Wahoo Blue SC sensor and Bluetooth heart rate monitor.

At times I am running my iPhone with music playing through a Bluetooth headset however all associated apps are off, except for Zwift Companion (which I have switched off mobile link). Im not sure if the drop outs in resistance are related to it trying to send the signal to the iPhone instead, even though all apps are closed and only Bluetooth headphones are connected.

Trainer - Tacx Vortex (latest firmware)
Device running Zwift - IOS
Connection - BLE
Zwift Game version - v1.3.30327
Firmware - latest from Tacx
Mode - sim

Trainer - Wahoo Kickr Snap v2 ~2017
Device running Zwift - IOS
Connection - BLE
Zwift Game version - v1.3.30327
Firmware - 2.3.62
Mode - sim

Thank you for the heads up Terry! Logging this with the other cases.

Actually I don’t think it’s related to interference from another Bluetooth device (ie iPhone) as I had the BT off before a ride just an hour ago and the signal dropped.

Turning off and back on the Bluetooth on the ipad and then ensuring the items are paired up again got it going again.

On the Kickr Snap, I can tell when it drops off as the blue LED does not flash every few seconds.

I have just bought the new Kickr core updated to the latest firmware v1.0.4 - 26 September 2018 using the latest Zwift and getting no resistance

Trainer Kicker core firmware v1.0.4 - 26 September 2018
Devise running Zwift IOS Latest update 12
Connection BLE
Zwift game version 1.3.30327

I get resistance if I use the Bkool app and the Kickr app

As an edit

Just used my core and Zwift and noticed that when I connect to Zwift and connect up my core to power and the controllable ,candence and tickr heart monitor the blue light flashes for Bluetooth, as soon as I press the button to ride the blue light stops flashing and if I go back to the connection page all is connected except the controllable

Hi Chris,

I’ll need to verify that the Kickr Core is fully supported for use with Zwift when paired via BLE. It’s supported for use when paired to Zwift via ANT+ FE-C (we support all smart trainers that connect with the ANT+ FE-C protocol), but I’m not sure about Bluetooth.

As I understand, the Kickr Core is a brand new trainer that was just release within the last few months and I’m not yet seeing it listed as a supported trainer on our hardware page or the Zwift support KB “Which Trainers does Zwift support?

Do you have a computer that meets our minimum requirements and an ANT+ dongle that you can use for Zwift? If so, I’d recommend giving that a try and let us know if the resistance works better.

Thanks for the reply
I don’t have a pc to use but have just ordered a wahoo ant+ key and adapter for my iPad so will update this once received and checked

Hi Chris,

You may want to reconsider the Wahoo Key. I regret to inform you that the Wahoo key is not currently supported in Zwift. In the past, some riders have reportedly been able to use these devices with Zwift, but they’re generally known to be buggy and not work consistently well.

Zwift includes partial support for ANT+ on iOS/tvOS, the exception being that you cannot get controlled resistance from a smart trainer. If you’re planning on using ANT+ on iOS/tvOS, you have only two recommended options to bridge the signal:

Viiiiva Heart Rate Monitor.
NPE CABLE: You can find a helpful setup video here on YouTube.

Unless you use a computer for Zwift, BLE is going to be your only solution if you want controlled resistance from your Wahoo Kickr Core.

The good news is that I’ve confirmed that members of our team have been using the new Kickr Core trainers and they should work just fine with Zwift if paired via BLE or ANT+. At this point, I’ll need to create a support case for this issue and flag it up to our dev team. I’ll contact you via email with further information/instructions.

Thanks again!

Thanks email received and I will try the step you mention and report back
Many thanks for your Help

I am one of the users experiencing large resistance changes (i.e. a 1% change in incline is like a 5% increase). I’ve had the same set-up and never any issues with the hardware prior to the summer. Same powermeter offset on Elite’s app.


I have tried the steps in the email and it still drops connection as soon as I ride or enter event
Will send my logs in from the last ride

I think I have found the problem or at least a work around ,when everything connects to Zwift I loose the resistance once I click let’s go or ride , the bike I have on the Kickr core is a Giant TCR Pro 1 with the ridesense Bluetooth speed and candence sensors fitted, if I disconnect the candence in the Zwift app it all works ,

I will play about with it over the next few days and order a wahoo candence sensor to see what happens then,

Thanks for your help and I will me back in touch with an update

So then you loose the cadence stats?

With disconnecting the Giant ridesense sensor yes you loose cadence stats, but I bought another Bluetooth cadence sensor and connected that to the bikes crank arm and Zwift ios and all works again with no loss of resistance

Ah ok, I’ve been running a BT speed / cadence sensor and get drop outs every now and then.

If your BT speed/cadence sensor is trying to send both signals this may be your problem, the Giant ridesense sends both signals and I think there was a conflict , your kickr will provide the speed read out so no separate sensor is needed for that
The Bt cadence sensor I bought was a Halfords own brand but I may change it to a wahoo one

It shouldn’t really matter though because of what you pair up in Zwift. Mine is a Wahoo cadence and speed sensor which when it works, it works fine. I didn’t know the Kickr Snap does a speed read out, however I think the Wahoo speed / cadence sensor would be more accurate.

Sorry did not realise you had the Kickr snap but according to the wahoo website it provides : Metrics: Speed, power, distance
But may be not

2 kickr 2017 units one snap one standard
Both running v 3.4.67-27 firmware from June 2018

2 iPad mini4
One on ios11
One on ios12



Most pronounced issues in ERG mode
Prior report:

What I have noticed is that when I connect the Kickr Snap to my ipad, it all hooks up fine.
If I join a event or free ride and leave it idle for a period of time, the controllable trainer seems to drop out.