I am sorry for the brief comment earlier. I accidently posted wirhout completing my message. I am having trouble with my Trek Incite 8i giving correct feedback. I have a Cobia 29'R and the instructions for the Incite said nothing about where to place the sensor on the front fork. Additionally, there was no information for the size of tire I am using so I did a roll-out test to figure the correct 4-digit number to enter into the computer. I'm sure I did the roll-out correctly and think it is the sensor placement that is causing me to get incorrect feedback. My computer is reading 2/10 of mile less than teammates when we ride the local track.
Hwvr, I think the sensor either works or it doesn't - i.e I am not sure where the sensor is placed will effect the distance - it will either be zero or what it is reading. Still worth checking again that :
1. The sensor is pretty high up the fork, if it is too far fm the computer, it may not be in range.
2. The magnet passes very close to the sensor - it shud pass accross the middle of the senser and be less than 2 cm - this can vary with system, I normally have pass about 5mm.
When you spin the tire, do you get an accurate speed reading ? also if you get close you shud hear a quiet click every time the magnet goes past - if this all seems OK, you may need to review your distance input again - can you not ask Trek for some advice on this ?