A bit strange the odometer changing. There is a calibration a procedure on the Caerbont website, that is for the speedo speed reading. You need accurately check how far you travel with one rev of the road wheel. I would check that the probe is still secure in it mounting hole (mine's in the front offside wheel). Ensure the when you rotate the road wheel the very small and dim LED on the back of the illuminates once per rev if I remember correctly, or was it 5 times per rev, instructions will clarify
