I’ve successfully been using a USB ANT+ dongle on a Windows 10 laptop for a a couple of months, connecting to my Garmin HR strap and Garmin Speed/Cadence sensor. This has been working fine up until today when I noticed massive spikes and dropouts on the speed/cadence. When on the pairing screen I noticed it now shows the Garmin Speed Cadence Sensor as a Seiko / Epson sensor. It’s definitely the correct sensor as I can see the speed move with the wheel. The HR monitor is fine.
I’ve spent a while today trying to figure this out and so far have found:
Garmin HR strap is fine
the same ANT+ usb stick in another computer with Zwift works correctly with the speed cadence sensor
Removing/replacing the battery in the Speed Cadence sensor makes no difference
Uninstalling the USB ANT+ device and drivers makes no difference
Another identical Garmin speed cadence sensor on a different bike is fine, shown correctly as a Garmin device in the sensors screen
Is there any way in Zwift or Windows to reset the Ant+ devices that have previously been connected? I’m at a bit of a loss as to what to do next.
Shuji at Zwift HQ here. You sound like a tech-savvy type, so I’m going to suggest a way to do a deeper troubleshooting step. I see several sessions on our server where you logged in / out today. I took the partial log.txt file from today’s first session and uploaded it to zwiftalizer.com. It’s a third party site that diagnoses issues with your session. It’s showing issues with your ANT+ signal, and lists some suggestions to improve it. Figured you’d want to resolve any interference issues while you’re at this.
I’d like to ask that you do the same from your end. Here’s where to find your log files
To answer your question - for Windows users, look in the Documents\Zwift folder for a file called knowndevices.xml. This is where your various sensors are recorded and saved. If you rename it knowndevices_original.xml (rather than delete it outright), it wipes the slate clean like you want.
The next time you start the Zwift app, you’ll have to pair everything from scratch. Then, when you exit the game app, it will write a new knowndevices.xml file in the same location.
@shooj Thank you very much for the quick and helpful response.
Yes, I’d logged in and out a number of times yesterday whilst looking into the issue, as well as an early morning ride (~40 min I think) which had the issues all the way through it. I think the Ant+ dropouts later in the day were likely me reconnecting the USB, trying a usb extension and generally resetting and testing everything whilst troubleshooting.
Looking at one of the log files for the morning ride (which had the spikes) it looks like I am not getting dropouts normally, but I will keep an eye on this. I hadn’t come across Zwiftanalizer and it is very good!
Anyway, back to my main issue. After posting this I re-installed Zwift on the laptop and started thinking it must be remembering information somewhere (as it remember my login). I discovered the Zwift folder under Documents and have re-named it to _original to start clean. I tested the connection after doing this and when searching for devices it found the speed cadence sensor without calling it Seiko/Epson. It was pretty late last night when I did this so couldn’t do a test ride but I will do a session this evening and see how it behaves - fingers crossed!
Incidentally another confusion I had (which is partly why it took me a long time to find the files under Documents) is in order to run Zwift as an administrator (which it seems to require) I do a run-as and specify a different user account, so of course I had to go in as that user to see the files under Documents
@shooj so I’ve done a complete ride this evening, with the speed/cadence sensor having the correct name and reading correctly. So letting Zwift generate a new knowndevices.xml appears to have done the trick.
Thanks very much for your quick and full response, especially when you must be so busy right now!
I am also having similar problems and not tech savvy.
I use an old style Garmin sensor. Still fantastic results on Garmin. Pretty good agreement between Zwift and Garmin initially. Now it’s changed to a Seiko Epson. HRate etc still agree. Pushing hard, high heart rate. 3Kmph. Low power.
FTP 173 12 week training Program FTP 115 now reading 8.
Garmin VO2 max increased five increments in the 12 weeks.
Non tech savvy explanation to set to original settings please.
You need to delete the knowndevices.xml settings file to allow it to forget the sensor and any previous settings associated with it. On Windows, within your Documents folder you have a folder called Zwift. The file should be in there with some others. Afraid I don’t know where it is on other platforms.
Garmin speed /cadence sensor out of battery.
Zwift was picking up the sensor in my F5. The one used for running, swimming etc.
Replace battery & connect to Garmin sensor.
