Magnetic. Thank you. Its actually been something Ive pondered. If it was weight triggered it wouldnt work well in the winter in AK. I always wondered about the bike thing. All in all a stop light is a glorified stop sign. Id fight it in court if I got a ticket for a light that didnt change in a reasonable amount of time.
I actually fight all traffic tickets. Have the local record for the longest traffic trial in history. 7 hours for an unsafe stop.
If you take it to court they will usually give you a lesser charge or offer the class if youve been a good boy. Well worth the time. I wish everybody fought their tickets. I make the local PD earn their fines. They been real bad money grubbers lately. Ive read many books on the subject and mostly its just to generate income for the department. Insurance companies love it too cause they can charge you more. Did you know? That statistically people who drive 10 mph over get in less accidents. They are more alert than the 55 crowd that are putting on their makeup and eating breakfast. Probably cause they are watching for cops. 
I actually fight all traffic tickets. Have the local record for the longest traffic trial in history. 7 hours for an unsafe stop.

