🚀 go-pugleaf

From article <-slj0+=.jps@netcom.com>, by jps@netcom.com (John Serafin):
> sagerian@delphinium.UUCP (Steve M. Sagerian) writes:
> 
>>I fact I was supprised no one mention that aluminum (sp?) wheels have no effect on the sensor at all.
> 
> Then how does an aluminum frame with aluminum wheels trip sensors?
> (It happens frequently.)
>>Stever
>> 

John, 
I responded to your query directly but I also wanted to relate my experience to the rest of rec.bicycles. As I was saying....

Yesterday, my significant other and I went out for a ride(the first near-nice day this spring). The traffic light near my home has the type of sensors/controller that this thread has been discussing so as I pulled up to it I immediately began to pay close attention to every event that happen. We were wanting to travel
straight thur the light but had the red light so we stopped in the right lane directly over the sensor. Moments later a car pulled into the left turn lane, also stopping on a sensor. The green light in the cross traffic lane turned yellow, then the left turn lane light for the car next to us, turned green,the left turn light turned yelllow but then the cross traffic light turned green! The controller never sensed that we were present on the sensor because my bike is an aluminum frame/wheels and my signific






ant others bike is also mostly aluminum. We had to cross the street by walking our bikes to the pedestrian crossing button and wait for the light again. 

Aluminum materials do not change the inductance of these sensor but most bikes are not completely aluminum either. (spokes,hubs,seat posts, handle bars, brake cables and assemblies. But even if these componets are made of ferrite materials,they may not be enough to change significantly the inductance of the sensor (enough for the traffic controller to sense your presence). 
A quick way to see if you bike parts are aluminum is to take a magnet to them...if the magnet sticks...it has some portion of it metal content is steel/ferrite material, if it does not stick then it is aluminum or plastic (who can tell now days?). 

And lastly, I wont claim that all senors are equal, I have no idea how many manufacturers of these things (auto sensors, traffic light controllers) but I suspect that there are at least two. I also suspect that for each manufacturer, the level of threshold (ie how much ferrites it takes to trigger a sensor) is different (the threshold level may be even controlable as some others in this thread have suggested..I dont know). 

enough..Steve