Help with setup - speed issues

Good evening,

I started using Zwift today but have experienced issues with my speed.

I’m using Zwift on a Windows 10 laptop. I have a Tacx Vortex trainer and have a speed sensor attached to the hub of my rear wheel. I also have an ANT+ adaptor which is connected to my laptop via USB.

I can load Zwift just fine and on the pairing screen, it shows my trainer is detected. However, when trying to ride, I start pedalling, my speed increases to around 5-10 kph and then drops to 0 whilst I’m still accelerating. I stop pedalling and as the trainer is slowing down, it starts to pickup the speed again - usually 3-5 kph.

I tried the calibration feature on Zwift which asked me to accelerate to 37 kph but I’m pedalling moderately and it doesn’t ever get over 3 kph - even though I must be doing well over 30.

Any help is appreciated!



How far away is that ANT+ dongle? They need to be pretty close to have a good signal, so you typically need to have a 6’ cable into which the dongle can be attached, so it can be close to your sensor/s.

The sensor was at least 2-3 feet away from my sensors…is this too far?

Watch this video review of your trainer by Shane Miller to see if any information in it can help you.

1 Like

Is there a possibility that a battery in your speed sensor is due for replacement? Is there a possibility that your speed sensor is dated and uses an old version of ANT+ (not ANT+ FE-C?) and cannot talk to Zwift quickly enough and often enough?

You can also drag your log file to and it will tell you how well your connection worked. This could be a very useful information for your troubleshooting.