There are a couple of different speed measuring devices available to law enforcement, the most popular stationary radar units are X, K, T and Y band, mobile units are Tribar (MDR), BEE III etc.... and then there are different models of laser, most are LT1.
What does this mean to you?

Radar operates with a big fat beam in a "V" from the device to what ever is out there, regardless of band, it will pick up the biggest/fastest (in that order) moving object... so if you are on you bike doing 100mph passing a heavy truck doing 60mph - the unit will read 60 until you are far enough from the tuck to register as the biggest and fastest in the beam.
If you're solo on the road then it's pretty easy to figure out that you're the speed demon!
Laser is a completely different story... a laser beam is emitted from the unit and placed directly on the item being measured, the only restriction is how far the operator can see... and if the unit is equipped with a high quality scope... that can amount to miles and miles!
Operators who are trained on both methods often don't even bother with radar anymore because the laser is so accurate.
When it comes to radar detectors, many motorcycle specific models are good, what is important to note are the restrictions placed on the devices by each respective State and or Province.
In Ontario for example... it is illegal to be operating a radar detector period, and if an officer suspects that you have one there is a warantless search authority provided in the Ontario Highway Traffic Act (HTA)... which means that if an officer thinks you've got one he/she is allowed under law to rip your bike apart to find it!
And don't think that you can hide it... about ten years ago the Ontario Provincial Police (OPP) developed a radar detector detector... so there is a device in existence that receives the signal sent out by your device!