oxygen

Hi folks - I have an Oxygen S-Cross Mk1 e-bike and I think the speed sensor has failed - it all works except the speed shows as 0.0 mph. Does anyone know where the speed sensor is - is there a magnet that should be attached to a spoke on the back wheel for instance or is this done another way...

Hi Has anyone had experience with riding both a Bosch CX performance motor with a badass dongle, and an Oxygen S Cross derestricted? I'd be interested to know how the 2 compared regarding degree of assistance and ease of maintaining speed. I have a bike with a Bosch CX motor and badass dongle...