Just bought a new Flux 2 less than a week ago .The speed (MPH) does not seem to change during a workout or it remains very low regardless of how fast I pedal
How many watts are you generating?
There’s an article that describes how Zwift calculates speed. I’d post the link but can’t. Just google how does Zwift calculate speed.
Basically output (watts), rider weight, height, incline, terrain, ingame bike etc are key factors.
What is your complete setup? And are you talking about your speed in Zwift, or on a cyclometer attached to your bike?
workouts hold you at a specific cadence/power and hence speed.
this is managed by “ERG mode” being activated.
if you increase your pressure on the pedals, the trainer will decrease the resistance, to keep you at a constant power that is dictated by the workout programme.
if you turn off ERG mode, it will be the same as a free ride, and the power you put out will decide your speed.