Still may not help.
If you were traveling at 20 kph, and a car, 50-100 ft. back were traveling at 50 kph, their speed, being the larger radar cross-section (at ten times the distance,) could show up when you crossed through the radar 'zone'. In effect, you could be getting their ticket. Think about it. The amount of metal that can reflect back at the radar gun is miniscule. Probably 5-10 square inches, max (and under most conditions, a couple of square inches) The metal which is not aligned to bounce the radar signal straight back at the radar receiver bounces it away in other directions... And part of the signal will be bounced off spokes, which are either at speeds from the bike speed down to zero, or at speeds up to twice the speed of the bike (it depends upon how far from the hub the spoke portion is.)
What this means is that the speed recorded by the radar, is actually the speed of the largest radar target in range and general direction as you are, of the gun. So, a car 10 times further away could easily have many times the cross section as you on the bike do. A person's body doesn't reflect radar - it absorbs it. (Which is why microwave ovens work...) The fork and frame tubes are all positioned at an angle, which would tend to bounce any signal up into the air. Plus, they have a round cross-section, which means that only a tiny 'strip' of the tube could bounce the signal back at the radar anyway. About the only portions of the bike which normally could return a signal are the handlebars, the spokes, and possibly the hubs. But, they're ALL a round cross section...
Only if there is no other traffic in range of the radar, would the radar speed measurement of a bike be accurate. And, maybe not even then, because of the spokes...