Oh, just general info: when installing, it's best to position the magnet and sensor as close as possible to the hub. That way the magnet moves past the sensor more slowly and it will be less likely to start missing counts at high speeds. Also, the closer to the hub the magnet is, the less effect it will have on wheel balance.

Also be sure to mount the magnet as recommended; if you mount it sideways, it can double-trigger the sensor as first the north then the south poles of the magnet go by the sensor.