knock sensor placement

How do I go about fitting a knock sensor when there is nowhere to bolt one one. I work on motorbikes and in-particular single cylinder 4str mx bikes. could a bracket be made to clamp the sensor around the cylinder? as long as its tight would this work? Ideal place would be top of the cylinder? or will it work anywhere on the head? Ive been looking at buying a knock dector for the dyno for a while but there is no where to bolt the sensor to.