Originally Posted by
LeeG
I don't think a bicycle has enough metal to trigger a signal light
I've never been unable to trigger a signal light. Remember, the signal sensor is electromagnetic, so the signal follows the inverse cube law. A pound of metal an inch from the sensor (your rim) has 1/(12^2) = 1/144th the effect of the same amount of metal 12 inches from the sensor. It's actually more than that since it's a loop of metal, so it reacts quite well with the signal.
The trick is, you have to know where the sensor is and put your wheel right over the loop. Given that, I've always been able to trigger light sensors.
Here's the standard reference for triggering lights with a bicycle:
http://www.humantransport.org/bicycl...nals/green.htm