Bit confused.
Waiting at the side of the road for friends, pedalling backward just spinning the legs thinking I wouldn’t go anywhere as roller and speed sensor weren’t moving.
My character started going forward.
I understand the cadence sensor works either direction, but how was Zwift calculating speed and power solely from the cadence sensor? Do I not need the speed sensor on the wheel?
Zwift will only move your avatar if it gets speed data from the speed sensor. The cadence sensor is just for data recording purposes, and controls the speed of the avatars legs animating. It should have no effect on the speed your avatar progresses down the road.
Is this something you can easily reproduce? If so, exactly what model of speed and cadence sensor do you have?
I will try it tonight and let you know (I’m in the UK)
I use the garmin magnetless speed & cadence sensors.
https://buy.garmin.com/en-GB/GB/shop-by-accesories/fitness-sensors/bike-speed-sensor-and-cadence-sensor/prod146897.html
Hi Jon
Easily reproduced.
Started an FTP test. Pedalled forwards to wake up my sensors and move my guy. Stopped. Pedalled backwards and he started moving. Registering speed and cadence
Could it be the speed sensor is mounted on the crank arm accidentally? Cadence has no effect on the motion of the rider in Zwift.
While on the device pairing screen can you see speed data coming in as mph or kph on the display just when pedaling backwards?
the sensors are mounted on the bike correctly. They cannot be incorrect due to design.
If they were wrong speed would be constant regardless of gear at 90rpm on my garmin. I also swap the speed sensor to my training wheel and when I firget, no speed is registered on my garmin.
They are 100% fitted correctly.
Speed was in miles
i can take a video if you provide an email address
Thanks a ton for the video Alan. We’re going to try and reproduce this here - have to say this is the first time we’ve seen anything like this! The video helps.
When you are at the pairing screen with the 5 big buttons to connect devices, can you pedal backwards there and see what the speed sensor says? It should show you the value in mph or kph.
Jon
Hi Jon.
I turned on the laptop and pedalled backwards from the start.
Cadence - Gave Reading
Speed Sensor - No Reading (but … it wouldn’t have been “awake” as it needs to rotate a few times).
Pedalled forward
Cadence - Gave a reading
Speed sensor - Gave a reading. (Woken up as wheel moves pedalling forward)
The game then loaded Video here https://youtu.be/oXIYAjd-8gE
I then went to the menu and pairing screen
Pedalling forwards
Cadence Sensor - Gave Reading
Speed Sensor - Gave Reading.
Pedalling backwards again
Cadence - gave reading
Speed Sensor - gave reading
Video here https://youtu.be/0wYGIEVYQBc
Apologies they’re not the best videos 
For the record - it doesn’t affect my enjoyment of the game - it’s just something I stumbled upon.