If you find that your wattage is fluctuating - dropping to zero and/or spiking - it's likely that Zwift isn't receiving all of your data packets due to your Bluetooth low energy (BLE) signal receiving interference. Much like other wireless signals, BLE operates on the 2.4 GHz frequency. This means anything transmitting on or interfering with that frequency can also interfere with BLE.
As BLE signal interference and dropouts aren't usually a Zwift problem, but a problem with your device/setup/environment, so this isn't an issue we can fix (as much as we wish we could!). Zwift only reads the data that's being sent to it.
While we can't solve this on our end, we've included the most common causes for interference and dropouts that we've seen so you can try going through a process of elimination and find the issue.
Here's the most common causes we see for BLE dropouts
- (Mobile Link only): Clear your app cache. On Android, this can be done through your settings. On iPhone, the easiest way to do it is to uninstall and reinstall the app.
- Dying sensor battery: If you haven't replaced the battery for your sensor recently, swap in a new one.
- Wireless signal interference: This includes any devices that transmit wireless signals or electromagnetic fields. See our example list at the bottom of the article.
- Fans: These generate an electromagnetic field around them that can block signals. Position fans so they're not in a direct line between your sensors and computer or phone.
- Wireless computer accessories: The USB dongle for your wireless mouse, keyboard, or other accessory can cause interference.
- Physical barriers: Any object that obscures line of sight from your computer or phone to your sensor can cause signal loss.
- Hardware failure: If you still experience issues after eliminating these factors, it's possible that your sensors are dying/dead. In this case, you may want to try borrowing a replacement from a friend to test with and verify.
Here's a list of potential wireless signal interference sources:
- Bluetooth headphones, speakers, or hearing aids
- Microwave ovens
- Direct Satellite Services (the coaxial cables and connectors can cause interference)
- Power sources (includes power lines or a breaker box in a wall)
- Cordless telephones
- Wireless video transmitters (e.g. Chromecast, AirPlay, etc.)
- Certain external monitors and LCD displays
- Any devices that use a cable to connect to a computer or power source
- Anything else that transmits a wireless signal, from routers to baby monitors
Additional Troubleshooting for ZML
If you're using the Zwift Mobile Link app to bridge your BLE connection, and you see it switch back to the "SNEAK A PEEK" screen, see this article.
If you're still experiencing dropouts after eliminating those causes, we can try and help you investigate. Just send us your log files, along with some pictures of the location of your trainer, sensors, and phone with the Mobile Link app (if applicable) through our ticket form. Again, we can't solve the problem, but we may be able to help point you in the right direction.