When it hits 0,0 it starts to count how many miles and how many litres you have used since it changed to reserve. So if you know your reserve tank is 3litres, it tells you how much of that 3litres you have already got through.
I work on the basis my car has approx 50miles left when the light hits red, so with the bike once it goes to 0.0 I gauge how much of my journey is left and where to fill up, when it gets to 25miles I start to get rather nervous.... but that's me being a wuss.
The trio computer returns once petrol has been filled. I have only learnt this by tryin