Are there permanently mounted bike computers? Over the years I've owned multiple bike computers (whose things that tell your speed/distance). Each time the head either falls off while I'm riding or I remove it, but lose it somewhere.

I want my next purchase to be one that is permanently affixed to my handlebars so that it never falls off or gets lost. I'm looking for one with strong mounting mechanism. I want to have to get out a screwdriver to replace the battery. I can't seem to find any one on the market that does this. Any help?
To err is human, but to really foul things up you need a computer.
  
  Paul R. Ehrlich


The best computer, is no computer at all! I am sure I will take flack for this, but if all you are interested in is speed and distance, why not go with an old style bike speedometer.  Permanent mounting and no batteries.  Just watch out for the roaming bands of bike hipster thieves, they may steal your whole bike to get at the speedometer.