Tell me if I'm wrong here but if the magnet is closer to the hub the magnet will make more RPM's vs if it's closer to the outer edge so how is it possible for the computer to accurately track distance and speed? Or is the inaccuracy negligible?
Yes, of course RPM is constant. But like some one mentioned - it is important that you give the magnet enough time to "pull" the sensing switch in the pickup unit.
Believe it or not, when i used to get fierce while riding rollers, i could get pickup sending units to "fail" or skip when riding at speeds near 50 mph. This was mostly because the unit was simply nearing being worn out. But it is proof that there was actual "mechanical" activity in older cat-eye and avocet units.
I assume they might still be using "reed switches." I don't know for sure. It seems I do still hear 'ticking."
By the way the "numbers" in the setup routine represent centimeters - even if you put in the wrong number - its hardly 50 feet per mile, in other words your only going to be off about 1 mile per hundred.
But I digress.