Orange Crush
Posts:4499
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| 05/16/2014 04:12 PM |
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Something that came to mind as I triggered the left hand turning light near home on my commute to work. Biking in the Vancouver area, about half the traffic lights get triggered, the other half is not sensitive enough to detect cyclists.
But if you ride a full carbon bike you could be out of luck, not enough metal for electromagnetic induction which is the principle on which these triggers operate. Anyone have experience with this? I was thinking of a carbon steed for my next high-end purchase but based on where I ride it could be a major disadvantage?
http://bikeportland.org/2010/09/27/bike-science-making-sense-out-of-signal-sensors-39517 |
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zootracer
Posts:835
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| 05/16/2014 06:25 PM |
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| You can buy a magnet that will attach to the underside of you pedals. Motorcycles use them... |
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Orange Crush
Posts:4499
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| 05/16/2014 06:36 PM |
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the portland article actually dispels the myth of magnets; you need metal, not magnets, for the EM induction. and motorcycles should not need anything at all, that's just baloney :-)
"The word on the street seems to be that the sensors are either weight or magnet based, but Koonce assures me that's not the case. The truth is, neither weight nor magnets will get you the green; the sensors are actually based upon the principles of electrical inductance" |
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dvs cycles
Posts:11
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| 05/16/2014 08:09 PM |
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Look for the loop cut in the asphalt and get as much of your bike or bikes in a group to trigger the electro magnetic inductance at the controller.
Here we have rectangles and circles. Lately they have been adding a cut through the loop so it can be ran in a figure 8 pattern and with twice as many windings in the center so more sensitive for MCs and bikes.
Get on the center winding for best effect.
In my days as an electrician I worked on a few traffic signals and rode with a city traffic engineer who set his cities sensors so cyclist would trigger them. |
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zootracer
Posts:835
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| 05/16/2014 08:50 PM |
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| Interesting about magnets. Another myth destroyed.....I have one signal light on my ride route. I go up or down a couple hundred feet and make a u-turn when safe. I have seen some cyclists do some crazy stuff just to avoid stopping.. |
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Dale
Posts:1767
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| 05/16/2014 09:13 PM |
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What are these traffic lights you guys keep talking about?
My town is so small we'd roll up the sidewalk at dark... if we had a sidewalk |
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Master50
Posts:340
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| 05/16/2014 10:09 PM |
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In Victoria they use a carbon bike with aluminum rims from one of the traffic tecks. When they put an induction loop in the road many are painted with a cyclist that indicates the place to stop to trigger the light.
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Oldfart
Posts:511
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| 05/17/2014 01:24 AM |
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| I seem able to trigger the lights with my carbon bikes. Metal rims though. Many lights now have push button triggers too. I know when I was a geologist student, the company I worked for drilled a lot of graphite in Timmins. We got a EM anomaly when geophysics was run over the area so maybe carbon bikes will trigger the EM field of the sensors at intersections? What about aluminum bikes? Non ferrous. |
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79pmooney
Posts:3189
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| 05/17/2014 01:28 AM |
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Portland has many lights with a bicycle symbol on the right edge of the sensor circle. Some I can trigger easily with any bike. Others, not with my ti bikes. There are other lights with hidden sensors that I trigger perhaps one in 20.
Ben |
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Orange Crush
Posts:4499
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| 05/17/2014 01:30 AM |
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Metal rims or a metal crank would be sufficient trigger. But what if you have carbon rims snd ceramic bearings?
The push bottons often get awkward especially if you have to go left. Dimwit "solution" |
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THE SKINNY
Posts:506
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| 05/17/2014 11:26 AM |
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| a lot of bike parts are aluminum which is non-ferrous. i think you need steel. what about the cleats on your shoes? |
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| How we spend our days is, of course, how we spend our lives. |
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Master50
Posts:340
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| 05/17/2014 11:34 AM |
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Posted By carl x on 05/17/2014 11:26 AM
a lot of bike parts are aluminum which is non-ferrous. i think you need steel. what about the cleats on your shoes?
The detectors work on non magnetic metals too. Electricity is created in the interaction of current and magnetic induction. The windings of a motor are copper or sometimes aluminum which are not ferrous. the current in the copper wire create magnetic fields that interact with the ferrous metals in the stator and armature but all the magnetism is created in non ferrous materials.
The less metal available the more sensitive the loops must be. at some point the sensitivity is set so fine the loop picks up vehicles in the adjacent lane which is counter productive so lazy traffic department set the sensitivity so low that even motorcycles don't trip the detector. |
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longslowdistance
Posts:2886
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| 05/17/2014 09:56 PM |
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Just to contribute to the discussion in a positive way, it's true that motorcycles may not trip the traffic light detectors. As a regular moto rider, I've never heard of magnets as a solution, seems like a pretty big unit would be needed but why not. What we do actually do and usually works is turn off then restart the engine. My state has a two traffic light cycle rule that forgives running a red light because of this issue.
As for bicycles: Carbon, steel whatever- Im surprised that a car detector would pick up any bicycle. |
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THE SKINNY
Posts:506
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| 05/18/2014 09:10 AM |
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| i guess i should've read the article. induction makes sense. i wonder if there is a device that could create enough induction in the sensor to trigger the light. |
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| How we spend our days is, of course, how we spend our lives. |
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Master50
Posts:340
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| 05/18/2014 06:24 PM |
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Posted By Frederick Jones on 05/17/2014 09:56 PM
Just to contribute to the discussion in a positive way, it's true that motorcycles may not trip the traffic light detectors. As a regular moto rider, I've never heard of magnets as a solution, seems like a pretty big unit would be needed but why not. What we do actually do and usually works is turn off then restart the engine. My state has a two traffic light cycle rule that forgives running a red light because of this issue.
As for bicycles: Carbon, steel whatever- Im surprised that a car detector would pick up any bicycle.
It isn't a car detector per se. It is a metal detector just like the guys at the beach or a mine detector.
There are several designs for signal loops. some do work better for bikes and motorcycles but the biggest thing is the amplifier and the technical set up. There are detector configurations well suited to detect a bike and if they can detect a bike they certainly detect anything with more metal in it.
Where we run into trouble is some loops are not very discerning in that they can detect the car in the adjacent lane so often the traffic control electrician sets it up very low sensitivity. Motorcyclist do buy loop trip magnets????? the thing is most loop detectors are set up to detect a motorcycle so everyone that owns the magnet reinforces the nonsense about them working. There is more than enough metal in any motorcycle to be detected if the loop is set up correctly and with motorcycles or bicycles in mind. The real problem with a magnet is they are using it to disturb a magnetic field with magnetism and not hysteresis so if the magnet is oriented in any way that cancels this interaction the effect is reducing the sensitivity or exactly the opposite effect. I have also spoken to motorcycle riders that have toll booth boxes and many think they are magnets even though they don't pick up steel. These re RFID devices like the anti theft things in packaged goods at the store.
Our traffic department has a lot of cyclists working there so they looked for the best bike detector patterns and we wire the loops with that in mind Our municipal government does a good job of it. They even paint the road with a bike symbol to help us place our bikes in the optimum place My carbon bike certainly trips the light. Now a lot of cyclists do not understand the painted symbol on the road or have no confidence to put their bike over the symbol 3 feet from the curb. they will wait for another vehicle, go pedestrian or often just run the light. |
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