1busa, a valid concern... In the older days, I installed an extra horn on top of the stocker, and it was hitting the front fender. But it was really sticking out, and at the time I didn't realize what I've done until I heard the clunking sound and saw the marks on the fender. However, I think if the nose hits the front fender in the two scenarios you described, a rider would have more serious problems to deal with. I hit a pothole so hard once that it bent both rims, however I don't believe the nose even touched the fender. A wheelie should never be landed hard - always on the gas. I am not a wheelie addict, and the few I've done where just 1-2 ft for a moment, and I managed to land them smoothly as butter - always on the gas. So, that's not an issue.
Arch, the Moto-Raptor is small (i.e. low profile), waterproof by design, and already comes with the mounting bracket and hardware. It was specifically designed to be installed under the nose on most any bike, and the company accumulated an extensive feedback from numerous users. As to the idea of installing in the back, it's a no-no. The signal will be so weak that this would defeat the entire purpose. Line of sight is the best for radar. The high frequency radio waves behave almost like light. They do go around to a small degree, but in such case the signal strength entering the detector could easily be many times weaker, effectively reducing the detection range from maybe 1-2 miles to maybe 1/4 - 1/2 mile or so.
This logic works well for the under nose mount. If the radar is shot from behind when a LEO follows a rider, it's usually a relatively short distance - 1/4 mile of less. So, the radar signal is very strong to begin with, and the detector will still pick it up, although possibly delayed by a couple of seconds. No one shoots stationary radar from behind while being miles away.
Here is one scenario illustrating the importance of mounting the detector to be in line of sight and therefore receiving maximum strength signal. Let's say a LEO is hiding behind an overpass and shooting from behind on passing vehicles. If the detector alerts you at that time, it's too late. However, as you are approaching an overpass, the reflected signal from other vehicles ahead of you gets picked up by your detector. Keep in mind that the reflected signal is already many times weaker than the signal coming out of a radar gun. You really don't want to create any additional circumstances which can weaken the signal even further.
