Brisbane City Council has recently installed Eco-counter induction sensors on some cycle pathways. They also produce a system that is good for counting cyclists in mixed traffic. You will see the double diamond layout of the sensors in the pavement if riding on the SE Bikeway through Ekibin Park. When combined with their pedestrian counting systems they can provide a count that will differentiate between pedestrians and cyclists.
Chambers Electronics uses a radio beam system to count and differentiate between pedestrians and cyclists. The advantage with this system is that it does not need to be installed in the pavement and so can easily be used on unsurfaced trails.