triggering traffic lights
 

just curious, if your bike is carbon or ti how do you trigger the traffic lights? (Seattle most lights
have a diamond or circle that you can trigger the light in, but I thought maybe incorrectly, that it
detected the metal on your bike)

Run them and make the issue moot. I've got a quarter ton motorcycle that can't trip some lights. You can bet you're S.O.L. on a bicycle at the same light.

I have no answer to your question but I heard that some states have laws (or are trying to pass a law) where in motorcycles can pass through a red light IF they come to a complete stop first and look both ways - just as if the light were a stop sign...

The law here in regards to that does NOT make them a 4-way stop. It requires you to wait for a "reasonable" amount of time to verify that it isn't on a timer rather than solely on a trip basis. It also only applies to left hand turns with a dedicated signal light. In other words: you can make your own green arrow after a few minutes and yielding to everyone else.

We use pole-mounted cameras. They aren't always bike-cognizant.

There are also induction loops that sense weight. For those, you have to eat like a pig for many months.

okay I'm not interested in how motorcycles scoff the law.

I ride a carbon fiber bike. There's enough metal in the drivetrain and what not to set off most sensors around where I live if you set yourself at the edge of the loops (the circles or diamonds mentioned in the original post). Occasionally, this doesn't work, and I either wait for a car that's coming to the intersection to set off the light or go press the walk button.

I'm with CastIron just come to a stop, look around, then go throught, but i prefer the take a quick glance as you come up to the light then proceed if it is clear.

They sense moving metal, not weight.... You've got to have enough metal close enough to the loop moving with enough velocity to induce a current in the loop... The trick with motorcycles was to lean the bike over so more metal was closer to the loop. There's actually one light near my house that was installed 2 years ago that's actually sensitive to bikes! Have no problems with my carbon Allez. Takes 5-seconds to change the light after you pull up. But after 6pm, it reverts to a fixed timer-cycle, every 5 minutes it changes... bizarre.. I wonder what the traffic folks were thinking about that...

a lot of my motorcyclist buddies have attached small magnets to their bikes that supposedly trip the lights. I just run em on my bike if there's no cross traffic.

Question - maybe I don't get this conversation, but how and why would you trigger traffic lights on any bike?

^^^ Provided you're at an intersection where there is a metal detecting plate in the road and you ride a steel bike, you can lay it down over the patch where the detector is. Upright, it might not be enough metal to be detected. Laid down, it might trigger it. Usually not worth the effort; just look for traffic and cross.

Funny. I ran a light last Sunday night. Crossing a one way street. Stopped. Didn't see any cars coming, so I pedaled through. Just as soon as I get through the intersection, I look over to see a patrol car sitting one car back going the other way. Gave the officer of the law a kind of "uh, sorry" look. He didn't seem to care.

You guys actually stop? :eek:

There's one particular left turn lane near my house that I can't trip at all. Of course it's at the start of one of my favorite routes. So I will either wait a full light cycle and then go on a red arrow, or until a car comes to trip it, whichever somes first. This means I often run a red arrow. I haven't had a problem yet.

Cops generally don't ticket cyclists. In 20+ years of cycling (and having been pulled over on group rides and solo a few times) I've only been lectured. Some woman cop did this to me the other day. I have cycling jerseys older than her. After 100K miles without getting flattened I seriously doubt the incident that results in my demise on the road will be me running a stop sign. More like some 17 year old kid text messaging on his cell phone. And he won't get a summons after he mows me down either. We KNOW that.

Dannoxyz has the right idea: Moving metal is the important thing due to induction.

If it is a single induction loop then you should ride along on edge of the loop.

A single induction loop looks like this when cut into the pavement:
_______
\ /
\___ /


A double induction loop looks like this:

_______
\ | /
\_|_ /

and you should ride ride down the middle of it. (Sorry for the crude ascii art.)

The double loops are much more bike friendly as teh local DOT can turn the gain WAY up. The single loop ones can get false positives from vehicles in adjoining lanes is the gain is set high enough to detect a bike. The double loop ones will get cancellation from a vehicle in an adjoining lane so they can turn up the sensitivity enough to detect a bike.

If you are really in a bind you can find the highest concentration of magnetic metal in your bike (probably the headset) and drag that along one of the wires embedded in the pavement. I've never had to go to that extreme.

(In edit: I cannot get the ascii art to look right: spaces in the edit screen don't translate to the post properly. The single loop inductor is a trapazoid. The double loop inductor is a trapazoid that is bisected by a vertical line. Hope that helps.)

Same problem for same reason with same legal responsibilities and often, the same solution. Interested now?