I run with a dumb treadmill and an NPE Runn.
I’m seeing that during a run my reported speed bounces above and below what the treadmill is set to by 0.3 mph either way. I guess this is a lot to do with treadmill quality and how well the motor compensates for the showing of the belt with each foot strike.
Over the run the actual recorded minutes per mile is very close to wear the treadmill speed is set to so it’s not so much an accuracy issue.
I feel it would be better if the reported speed was at an average of the last 5 seconds so it didn’t fluctuate as much.
Similar to the 3 second or instant option in the settings for cycling.