Power Reading “Dropping” with Smart Trainers

Each season more athletes convert to smart trainers such as Wahoo, Cyclops, or Tacx, and using programs like Zwift, TrainerRoad, or Rouvy. New converts are surprised when they experience power dropping to 0 during a workout. So what’s the fix for power drops?

We see this question arise multiple times on our triathlon team forum throughout the year so we want to address it at the height of indoor training season! The issue actually varies in severity depending on what’s happening in your personal situation. So let’s assess and get you riding cleanly: Below I have broken down your potential experience and various methods to troubleshoot.

  1. If power disappears for a substantial duration (several seconds or longer). 
    1. Signal Strength: If you’re using USB as a connection point to receive data, it needs to be close to your smart trainer (ideally, within a foot).  One solution is to get a USB extension cable so that you can get the +ANT dongle (make sure it’s version 2.0 or higher) right next to the smart trainer.
    2. WIFi Signal: Everything might be ok with your setup except that your WiFi isn’t strong enough. Thus, what you’re seeing on the screen isn’t refreshing at the rate you are pedaling.  To fix this, either move your setup to a different room or use different WiFi range extension techniques.
    3. WiFi Interference: Ideally, your WiFi is set to a lower channel (e.g. 1-3).  This link gives you great info on how to change the channel on your home router.
    4. Signal Interference: Turn off all Bluetooth and +ANT devices in the area.  Also, ensure there is nothing connected to your device.
    5. Software Interference: Make sure other programs that use +ANT like Garmin Express and Garmin Agent are not running in the background of your computer or mobile device.

  2. If power drops for a second or less but this occurs throughout the session. 
    1. Firmware: Update your firmware and make sure you do a spin down to ensure everything is setup correctly.
    2. Data Overload: If you have power, cadence, and controllable power all running through Bluetooth or +ANT, you might be sending too much data for your device to handle.  The solution is to send your power via Bluetooth and cadence through +ANT.  This video demonstrates how to do this on Zwift.

  3. If power drops occur more frequently at a higher cadence (e.g. 90-95 rpm) than a lower cadence (e.g. 70-75 rpm).
    1. Pedaling technique: This is probably “user error” friends. Try spinning with one leg clipped in at high cadence, then and again at low cadence.  Check if you hear a “clicking” sound at the top of your pedal stroke on either leg.  That noise would indicate that your pedal strop is not efficient and you need to incorporate one-legged drills into your future workouts!


  1. Great post! One other resource for this is Zwiftalizer (zwiftalizer.com). You can upload the log file from a Zwift workout, and it will analyze the file to identify dropouts, signal strength, refresh rate–all sorts of cool data. It can be a useful way to diagnose what problems you’re having and why you’re having them.

    Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s