i run a garmin edge 800 gps on my road bike and like to know how far ive ridden, though on the mtb i find it a distraction and a constant worry that it will be a scratch magnet. ive taken to placing it inside a travel soap dish and carrying it in my hydration/gear pack. since it dont need wheel sensors to give a reading and has very strong satilite connection it remains accurate though not as much as having the wheel sensors.