Samsung S8 w/ANT+ Zwift App issues

I’ve done a few rides now and I’m otherwise really enjoying the app and the training plan options to help me get back into shape after a couple years off of regular riding and training. So far, though, I have noticed that the power readings seem to have large lags on updates, which makes it hard to hit (and maintain) any training zones, especially shorter ones. I have tried both classic and vPower, as well as instant vs 3sec power. Maybe this is just an issue with my expectations/understanding around how Zwift measures power without a power meter, or an issue with the Zwift app and ANT+ on android, or some combination of the two.

My setup:

  • Samsung Galaxy S8 running Zwift app
  • CycleOps SuperMagneto PRO trainer
  • Garmin Speed Sensor (came with Garmin Edge 520 bundle)
  • Garmin Edge 520 separately recording readings and providing feedback to me
  • Garmin Cadence Sensor (also came with Edge 520), used on one ride
  • Have separately tried a Giant RideSense speed/cadence sensor (behaves the same as Garmin), used on two rides
  • Google Chromecast (casting S8 screen to larger monitor)
  • IpBike App on Android to double-check ANT+ data received by phone (only used on one ride)

My ANT+ speed sensor is sending updates to my Garmin Edge 520 with no issues. I place my phone very close to the ANT+ sensor and it makes no difference. I have even recorded the ANT+ data at the same time in a different app on the same phone with no issue (definitely no noticeable lag). I have the recorded data to compare between what Zwift records and the Edge 520 (and/or IpBike) record if anyone is interested.

Cases I’ve noticed:

  • It takes a while for my avatar to get moving at all and show any speed, even when doing a moderate effort from the get-go
  • Sudden but consistent changes in effort (e.g. go from 25mph on the Garmin to 20mph steady) taking ~10-20 seconds to update power (see this ride, specifically the intervals at 30-38min and 50-54min)
  • The readings themselves seem to settle in to relatively large bins (e.g. Trying to hit 210, will settle at 219 so I back off slowly, then eventually just jumps down to 180 or something). You can see this pretty clearly on this ride (I’d like to think I’m that supernaturally consistent, but let’s be real)
  • The power reading itself will sometimes drift up and down a decent amount, even when I hold a fairly constant speed/cadence (might just be an artifact of small changes in speed and the large delay on updates)

It seems to me as though the Zwift app just has trouble reading the ANT+ data from android, or at least this particular phone. I’ve ordered one of those heart rate monitors that does the bluetooth bridging, since I needed a new HR monitor anyway. I hope that will clear it up enough for now, and will at least give me the option to switch to the Companion app and a computer (hopefully it doesn’t suffer from similar issues).

I’m open to any settings on the phone that may be affecting this. Any help or feedback is appreciated!

For anyone having similar issues, ANT+ to bluetooth bridging seems to correct the problem. My 4iiii Heart Rate Monitor that bridges ANT+ to bluetooth arrived and I was able to test it. I did a ride yesterday and the power output looked as expected ( Hopefully the ANT+ native support on Android gets cleaned up, but this will do for now.

Update for anyone else that might have been having this issue:
An update since I posted this seems to have cleared it up. Whichever one enables ANT+ automatically on the selection screen. I just did a full workout on only ANT+ devices and everything worked as expected, albeit maybe with a slight delay on some sensor reading changes…