If you are sure it is calibrated correctly, it sounds like your computer is not picking up all the miles. Maybe it is stopping and starting. If it is wireless, maybe there is some kind of radio interference (other electronic devices). Are you sure you have everything in miles and not kilometers?

If all else fails, I would recommend that you start all over. Remove the battery and zero out the whole thing. Reinstall the battery and reprogram the computer and see if that helps. My friend's computer (a cateye) was spazzing out on him. The mph would be erratic. It would jump from 13mph to 25mph for no reason at all. Resetting fixed it all.[/QUOTE]


I think this is what it is- it's not reading every revolution. I think I'll try this and see if it works... thanks!