Wheel Speed Sensor

Hall Effect Sensor

Working in Progress - need really accurate wheel speed.

Cherry Hall Sensor for Gear Tooth Speed

Binned

The following only works a very low RPM and was found to not be suitable :(

Arduino Hall Effect Sensor

For low accuracy you can use a Reed Switch

Notes:

Hall Effect Sensor

http://www.freetronics.com/collections/modules/products/hall-effect-magnetic-and-proximity-sensor-module#.UTB5QzBTCf8

Hall Effect Magnetic and Proximity Sensor Module Quickstart Guide

Working

FI01 for counting input