There's about a million pages on the web about how to install these
speedos, so I won't go into details, but here's some photos of how
I mounted the sensor and magnet.
The sensor is just cable tied to the leg, with cable ties above
and below the caliper mount. It should be pretty well protected
back there.
The magnet is a pair of small rare-earth magnets out of an old hard disc
drive, epoxied the the disc carrier.