I had one fitted by the LBS I bought the bike from so I didn't set it up myself. Because of this I have never seen the instruction book so l don't even know which model it is, except that it states Cateye Velo on the readout case. lt must be a basic model as it only gives total and trip distances, time of day and time ridden as well as average and maximum speed. I've only used it for about 350 miles and the other week, just like the other member, the readout was still visible showing the total miles covered and the time, but not the actual speed and distance I was cycling at the time. I've also checked the alignment of the magnet and sender and repositioned the magnet from just above the sender to just below it and every millimetre in between as well as changing the battery in the sender unit but not the bar mounted computer. There are no other devices on the bars. On the battery cover it says: "Battery Reset press AC" There is a micro button marked "AC" just below and another alongside it which states: "Set". I'm not sure if one of these should be pressed when one or both of the batteries are replaced. Interested in fossyant's comment above.....if only l knew what it meant. Any advice or suggestions gratefully received.