Hello,
No, you don't need 5km long straight route, the condition is that speed must be more than 5km/h and vehicle must accelerate. I think the longer straight route you will drive during calibration the better, because difference between samples musn't be more than +/- 1 degree, also please check how is your device tightent to the motorcycle frame. You should find long, straight route, position your motorbike vertically to the ground (no tilt), check if there is GPS fix (readio 69, answer 1 means that GNSS ON with fix ) and ignition (readio 239, 1 - ignition ON), then send " auto_calibrate:set" to device and start to drive with acceleration without tilting motorcycle, the longer you will be able to accelerate the better.
Regards