You are in good company. Most people haven't a clue on how the magic lights work;)

Doesn't make a difference. The coils work by inducing current flow from moving a conductive material through the magnetic field. Carbon fiber and aluminum are conductive...just not magnetic. Line up on the middle of line of the coil and ride the entire length (It'll work with your motorcycle too;)) of the loop. Like this

http://www.bikexprt.com/bicycle/imag...20closeupa.jpg


It'll trip in most cases. I have a less than 5% failure rate if I know where the loop is.

hmm...
I have a particularly annoying intersection at iliff and colorado blvd. Silly me has been sitting on the right side of the loop. Tomorrow I will give a go at the middle.

I don't usually scofflaw but there is this pair of traffic lights on 2 T-intersections that are mere 20 yards away from each other that are, for some reason, never green or red at the same time even at 6 in the morning. These lights seems to be timed too so they cycle through even though there are no cars in sight. So, naturally, I just blow through these lights in the morning.

But this morning a police SUV caught me doing this. He did not stop me though. He paced next to me and I heard "Excuse me!". I looked and it was the Police. He says, "You know, you still need to stop on red lights."

Without slowing down my pace I gave him the most apologetic face I can muster and I said "I'm sorry."

He says "OK." and he drove off.

I still managed to blow 3-4 red lights for the rest of my commute.

I know. I should not blow red lights. But its 6 am and there are no cars in sight. I slow down to make sure the roads are clear though.

EDIT: I take back I don't usually scofflaw. I just realized I do. :D

Same for Washington, D.C. These murder-capital cops have bigger fish to fry (such as ticketing jaywalkers) and are used to bicycle messengers, capable of breaking 10 traffic laws within one intersection. Any shenanigans I pull are well within the standards, and I always do a 360 glance before doing anything that could earn me a ticket. I'm too cheap.

i don't know if someone mentioned this but it works for me:

When you're stopped at the light, tilt your bike down so it's almost laying down flat over the sensor. Only really works if you have a steel bike.

No need to lay your bike down. The wheels will do an excellent job if positioned correctly. From Steve Goodridge's excellent articles, the following illustrates how the wheels interact with the loop.

http://www.humantransport.org/bicycl...als/wheels.gif

The wheels are what interacts with the induction coil. The frame interacts to a much lesser extent because of it's distance from the coil. That's why you have to lay the bike down on the loops if you don't ride directly over the most sensitive part of the loop.

And, again, the bike doesn't have to be steel. Any material that will conduct electricity will work. That means aluminum, steel, titanium, lead, magnesium, rubidium:eek::eek::eek: or carbon fiber (as well as about a hundred more exotic metals) will work.

Keep up the good work cycco!

Did you go watch the video? The safety guys at my work actually linked to that;)

The one with the girl in the yellow shirt? That's all I remember.

(I watched a bit with no sound)

Al

Doesn't matter. It's not a steel detector, it's an inductive loop, and anything conductive will trigger it. The wheel rims are a hell of a lot closer than the frame so they'll make the biggest impact. As long as you have conductive wheel rims and you plant them right on top of the loop (NOT in the middle) you've got nearly as good a chance of triggering it with a carbon frame as someone riding a steel frame.

Watch a little more. It's got lots of cool boomby bits...especially if you like seeing bathtubes explode;)

Hey, new member here. I haven't read this entire thread, but I am an EE and I think I have a general idea of how light sensors work.

The light sensor is a giant metal detector that detects inductive objects that are aligned with the magnetic field it produces. By "aligned inductive objects" I mean large, horizontal steel objects (like a car/truck frame, for example). Motorcycles have the same problem as bikes do with setting them off. You could lay your bike down like one poster mentioned, but there is a product out there that is basically an inductor you put on the bottom of your motorcycle.

Something like this:

http://www.amazon.com/Amanet-RLC-40-.../dp/B000NPNXOW

It definately doesn't matter what frame you have. When I rode my steel touring bike with big ol marathon plus tires there were 5-6 lights I could never get. No matter where I stopped along the loop in the street. Now my Ti Road bike with pretty hefty deepv/aeroish wheels and 25mm tires it seems to get all but two on my route. I have ridden the tourer since so they haven't adjusted anything on the sensors.

That's interesting. I wonder if the distance between rim and sensor (tire thickness) has a bigger effect than what ones frame is made of.
Al

Actually I face both the problem of both paved over and too many changes. One area near my home in the northern direction has been paved over and I can't figure out where the loops are.

In the eastward direction there are old loops visible with new loops... and I can't tell which are old and which are new.

I have reported both to the city... with no change.

Results after 3 days of trying to trip the signals:

Intersection #1... 3 for 3 success
Intersection #2... 2 for 2 success... 3rd time I had a car trip it for me.
Intersection #3... 0 for 1.5 success... 1 time a car tripped it for me. The other I couldn't tell if it was me or the car that came up behind me. It definitely wouldn't go the first time. I don't use that intersection much and only went that way on purpose to try it out.

In any event, thanks for the education. I never even tried because I had always read or heard that bikes wouldn't work.

Now you can impress the natives with the magic flame;)

Depending on the city and the lights and time, I've found that many lights that operate on sensors still have a timing function to change just in case they didn't get 'tripped' properly.

The city I ride in has all of the lights in downtown on timers to facilitate traffic flow. Especially one road. When I'm driving if I can made the first light I can make the next 8 lights (all the way through downtown) just by driving the speed limit.

Here's an interesting (to me at least) anecdote. The left turn signal to turn into my neighborhood pretty much never triggers for me while I'm on my bike. I reported the signal to the state and they told me that no signals in the state are set up to detect bikes. They never responded when I mentioned that I don't have this problem anywhere else but at this particular light. It's not a big deal as left turns are free but at high traffic times, that can sometimes mean waiting a few minutes.

So a few weeks ago, I had the studded tires on my commuter due to some snow and I pulled up at the light in the same spot I always do (right in the center of the lane over the wire) and lo and behold, I get the left turn signal. The next day, I watched a motorist stopped at the light and he did NOT get the left turn signal when the light went green. This either lends some credence to the possibility that some sensors are so sensitive that a small change in distance from metal to the wire could have an effect (my studs are closer to the ground than the metal rim of a car wheel), or the signal is just intermittent.

Either way, these types of threads are why this forum is so useful.

Absolutely. When I had both a 600 pound motorcycle and 23 pound bicycle one local detector would pick up the bicycle just fine, but not the motorcycle. I positioned both exactly the same- over the sawcut. The bicycle has 1" tires while the motorcycle tires had 4" tall section cross sections.

On my daily commute I have a left turn with an arrow that USED to change regardless of whether a vehicle was waiting. Then one day a year ago the DOT changed it to only signal when triggered.

I'm not a scofflaw at all so I contacted our local liaison to the NCDOT and asked them to change it back. She forwarded their response, which was (essentially), "We'll consider it. In the meantime try making sure your bicycle is right in the center of the lane [I'd already been doing that to no avail]. If that doesn't work just run the light when it's safe to do so."

I've always wondered whether a police officer would buy that justification if I made the left without a signal (now it changes some times but not others; this morning it didn't). "But officer, the DOT won't fix that light and they even TOLD me to run it!"

And yes, I did keep the email. ;)