Hi all, my tacho has suddenly decided to flicker around like mad back and forth at crazy speeds. The cable seems to be fine and in good nic, has anyone got any idea what this might be?

Hi all, my tacho has suddenly decided to flicker around like mad back and forth at crazy speeds. The cable seems to be fine and in good nic, has anyone got any idea what this might be?

I don't know but could it be indicating a 'fault'. Some bikes have diagnostic capability

Does it keep flicking to a certain rev number or speed number?

It's not a digital one, it's mechanical. It just goes completely haywire, all the way clockwise then anti-clockwise really fast

The counter head needs servicing. It is trying to screw itself completely around the clock.