Originally Posted by
kbblodorn
which metal strip do you pull over to trip the sensor, the one parallel to the direction of travel, or perpendicular? I'm guessing the parrallel one would expose more of the sensor to the steel in the bike. (I don't think the aluminum trips the light, but rather the steel in the BB. I think it needs to be a ferrous metal.)
This is a regular on bikeforums. The detection loops work thro' induction and will/should be affected by any electrical conducting material, not just ferrous.
Read
http://www.phred.org/~josh/bike/SignalDetection.html for a full explanation.