This is a question a lot of people new to indoor indoor cycling ask – why is the distance and speed on my head unit different to FulGaz? The short answer is, it doesn’t matter.
Simply put, the two will never perfectly match – and that’s not a problem!
To delve a little deeper into this issue, FulGaz adjusts your on-screen speed based on power output and the gradient of the virtual road (plus other physics calculations around rider weight, aerodynamic drag, rolling resistance, etc).
Your Garmin or Wahoo (other brands available) head unit is receiving basic data from either rear wheel speed for older wheel-on turbo trainers or a combination of power and the “speed” your trainer is spinning at. Your head unit isn’t communicating directly with FulGaz, so it doesn’t know your weight or aerodynamic drag or whether you are grinding your way up a European climb or chasing the speeding bunch around a local criterium course!
It can be quite confusing seeing your on-screen FulGaz speed vary so much from the speed on your Garmin, but my advice is to simply turn off your head unit! It’s not necessary. Use the data from FulGaz.
FulGaz can automatically upload your ride directly to Strava, Training Peaks or Today’s Plan. Your ride data is also emailed to you after each ride for manual uploading to your software of choice. There is no need to “double record” your ride using a separate head unit.