Don't Allow Pairing To A Device That's Actively Paired To Another Zwift Rider

My wife and I are both Zwift riders with separate Kickr’s. In the last month, I’ve began 4 or so of my races/events before noticing unusual and annoying resistence/behavior, especially when she’s climbing extreme grades. I could troubleshoot when I notice the issue but would rather remain in the event I’ve entered. I’ve discovered the problem occurs because occasionally my Zwift (Windows) app will re-pair to my wife’s Kickr (forgetting my earlier pairing). This is easy to miss on the initial pairing screen since it only appears for a few seconds when all sensors pair to a device. The pairing page should “remember” it’s previous paired devices but for some reason, sometimes pairs to my wife’s. I’ve now memorized the device ids and pay closer attention during the pairing screen display, but it would be very nice if the app could warn or prevent me from pairing to another device that’s already paired to another active user (my wife).

Adding my vote to this request. Both my husband and I have Kickr’s. His Kickr has a lower ANT device number than mine so Zwift (Windows) app often automatically pairs to his instead of mine - even though I only ever use mine Kickr with Zwift.
I’d simplify the feature request to: Zwift should remember the paired devices from the previous session and should automatically attempt to pair to those devices first.

1 Like

Similar issue with two Tacx 2T trainers in same room, two PCs, two accounts, two ANT+ connections.

Zwift will happily cross-pair the trainers, e.g., pair power of trainer 1 and controller of trainer 2 and vice versa. Makes for some fun joint rides!

This after having everything previously paired correctly. Even more, after re-pairing correctly, I sometimes still see the other trainers channel data in the Zwift log using Zwiftalyzer.

1 Like

Remove the incorrect trainer from the listing in the knowndevices.xml file.

I think that should help.

Btw broadcasting the signal everywhere is what ant+ does, I’m not sure what the device is connected to is transmitted in the ant+ data, so I doubt zwift could make your request happen.

1 Like

This is also being discussed here. Waiting to see if there is a solution.
Did the knowndevices file change as suggested by Shuji /Zwift.
Will see how it goes.

While of course they should fix it, in the meantime is it possible to rename the trainers so it’s more obvious which is which?

1 Like

OK, great suggestions for sure. But, changing known devices does not influence anything as zwift rewrites it upon closing the program. Clearly zwift reacquires ALL the devices upon startup and saves them upon closing the program.
There are last device listings in prefs.xml, but zwift does not apparently choose those last devices upon startup. I edited this file to specify the correct last ANT+ identifier, but it seems to make no real difference. If your device re-pairs then I’m thinking anything can happen, i.e., cross-trainer pairing.
Also, if you look at log.txt, you can see that zwift identifies the various ANT+ connections by name/number; so why are connections so unpredictable?

I can confirm that doing anything with the KNOWNDEVICES file does nothing.

This issue is highly annoying

Following up on “sometimes still see the other trainers channel data in the log using Zwiftalyzer.” This behavior appears to be a bug in Zwiftalyzer: after a channel is assigned to a device that is subsequently re-paired in the user interface, the log analyzer incorrectly uses the old name for data from a new secondary channel that would normally be ignored by Zwiftalyzer.

Regardless, the problem of cross connecting trainers with different user interface and internal identifiers continues.

This is not an easy one to fix. The devices themselves don’t broadcast which other devices they’re connected to; the only thing Zwift could do would be to poll all current connected users and see if the same device ID has been already connected by another user. Not a simple proposition.

The other alternative is better device management in the app: giving priority to the last connected devices (TR does this pretty well), allowing devices to be renamed (not sure if Zwift allows that, many apps/devices do), and allowing devices to be forgotten (the iOS way - but this one can also generate a lot of service calls from “I forgot I had removed that device”).


I’d be happy if zwift only paired to a new device if you intentionally click the search button (like my garmin! Never ever paired to the wrong device!) but as it is, it will find my wife’s trainer ALL THE DAMN TIME, even after I delete the prefs and known devices files. It’s a huge pain if you don’t notice until you start racing or something.
FWIW, the only clue I get is that zwift won’t automatically advance to the game with an unknown device you have to click through but that’s a pretty tepid clue.

Bumping this. Should be a relatively simple fix for an annoying issue. Why does knowndevices even exist if Zwift ignores everything in it when starting up?