Rowly,
Yes, your right, it is a little exposed!! I did this part in a bit of a hurry. I did use a nyloc tho'!!
I do have plans to make a better bracket that the sensor will locate into rather than sit ontop of, this should stop any possible rotation of the sensor around the bolt.
It's also a little closer to the fan belt than I'd like, I might reposition it aswell, but that means rotating the trigger disc a little.
Regards,
Nick