Originally Posted by SoonerBent
I used to be the field manager for a company that installed vehicle detectors. Let me add my .02 worth.
Detectors will pick up non-ferrous metal, however, ferrous metal is detected much more easily.
It doesn't matter the shape of the metal being detected, a cube, sheet or hoop all look the same to a detector. It's mass that's important, the metal of the vehicle adds to the force of the magnetic field created by detector. This is done by intersecting the lines of the magnetic feild created by the detector so mass the important factor. The more magnetic lines you intersect, the better. That's why laying a bike over the loop will work better than a standing bike.
The magnet idea is ridiculous. A magnet will not create a difference in the magnetic feild of the detector loop that will cause a difference in the current through the loop, which is what the electronics of the sensor actually detect.
Here is a very good article on the subject.
http://www.hgsc.bcm.tmc.edu/~havlak/...detectors.text
SB
Thats right. Even aluminum rims and/or a crank will be enough for a properly tuned sensor. I did a test in my hood and carried my front wheel to a couple of intersections and sure enough just the front wheel alone standing on tire over center wire of triple wire sensor was enough to trigger.
If your aluminim rims and crank are not triggering the sensor and you have bike in proper position and you wait for traffic control system to change light (it may take a couple minutes after you trigger or it may require more than one vehicle to be in line) and it still doesn't work then you really should call your public works or traffic dept. and file a friendly request to have the sensor tuned properly.
Al