I'm a high school cross country coach who prefers to take the kids to a dirt road to do our threshold work. I've wheeled the distance for years, but never really trusted the results; the road is rocky and uneven, and the wheel does a fair amount of bouncing around. Ijust bought a Garmin FR60, which has been given excellent distances for known loops I've run for years. Does anyone know which instrument will most likely yield the most accurate distances? I appreciate any helpful input.